doc_id int32 0 2.25M | text stringlengths 101 8.13k | source stringlengths 38 44 |
|---|---|---|
9,600 | Excel supports dates with years in the range 1900–9999, except that December 31, 1899, can be entered as 0 and is displayed as 0-jan-1900. | https://en.wikipedia.org/wiki?curid=20268 |
9,601 | Converting a fraction of a day into hours, minutes and days by treating it as a moment on the day January 1, 1900, does not work for a negative fraction. | https://en.wikipedia.org/wiki?curid=20268 |
9,602 | Entering text that happens to be in a form that is interpreted as a date, the text can be unintentionally changed to a standard date format. A similar problem occurs when a text happens to be in the form of a floating-point notation of a number. In these cases the original exact text cannot be recovered from the result. Formatting the cell as TEXT before entering ambiguous text prevents Excel from converting to a date. | https://en.wikipedia.org/wiki?curid=20268 |
9,603 | This issue has caused a well known problem in the analysis of DNA, for example in bioinformatics. As first reported in 2004, genetic scientists found that Excel automatically and incorrectly converts certain gene names into dates. A follow-up study in 2016 found many peer reviewed scientific journal papers had been affected and that "Of the selected journals, the proportion of published articles with Excel files containing gene lists that are affected by gene name errors is 19.6 %." Excel parses the copied and pasted data and sometimes changes them depending on what it thinks they are. For example, MARCH1 (Membrane Associated Ring-CH-type finger 1) gets converted to the date March 1 (1-Mar) and SEPT2 (Septin 2) is converted into September 2 (2-Sep) etc. While some secondary news sources reported this as a fault with Excel, the original authors of the 2016 paper placed the blame with the researchers misusing Excel. | https://en.wikipedia.org/wiki?curid=20268 |
9,604 | In August 2020 the HUGO Gene Nomenclature Committee (HGNC) published new guidelines in the journal Nature regarding gene naming in order to avoid issues with "symbols that affect data handling and retrieval." So far 27 genes have been renamed, including changing MARCH1 to MARCHF1 and SEPT1 to SEPTIN1 in order to avoid accidental conversion of the gene names into dates. | https://en.wikipedia.org/wiki?curid=20268 |
9,605 | Microsoft Excel will not open two documents with the same name and instead will display the following error: | https://en.wikipedia.org/wiki?curid=20268 |
9,606 | The reason is for calculation ambiguity with linked cells. If there is a cell , and there are two books named "Book1" open, there is no way to tell which one the user means. | https://en.wikipedia.org/wiki?curid=20268 |
9,607 | Microsoft originally marketed a spreadsheet program called Multiplan in 1982. Multiplan became very popular on CP/M systems, but on MS-DOS systems it lost popularity to Lotus 1-2-3. Microsoft released the first version of Excel for the Macintosh on September 30, 1985, and the first Windows version was 2.05 (to synchronize with the Macintosh version 2.2) on November 19, 1987. Lotus was slow to bring 1-2-3 to Windows and by the early 1990s, Excel had started to outsell 1-2-3 and helped Microsoft achieve its position as a leading PC software developer. This accomplishment solidified Microsoft as a valid competitor and showed its future of developing GUI software. Microsoft maintained its advantage with regular new releases, every two years or so. | https://en.wikipedia.org/wiki?curid=20268 |
9,608 | Excel 2.0 is the first version of Excel for the Intel platform. Versions prior to 2.0 were only available on the Apple Macintosh. | https://en.wikipedia.org/wiki?curid=20268 |
9,609 | The first Windows version was labeled "2" to correspond to the Mac version. It was announced on October 6, 1987 and released on November 19. This included a run-time version of Windows. | https://en.wikipedia.org/wiki?curid=20268 |
9,610 | "BYTE" in 1989 listed Excel for Windows as among the "Distinction" winners of the BYTE Awards. The magazine stated that the port of the "extraordinary" Macintosh version "shines", with a user interface as good as or better than the original. | https://en.wikipedia.org/wiki?curid=20268 |
9,611 | Included toolbars, drawing capabilities, outlining, add-in support, 3D charts, and many more new features. | https://en.wikipedia.org/wiki?curid=20268 |
9,612 | Also, an easter egg in Excel 4.0 reveals a hidden animation of a dancing set of numbers 1 through 3, representing Lotus 1-2-3, which is then crushed by an Excel logo. | https://en.wikipedia.org/wiki?curid=20268 |
9,613 | With version 5.0, Excel has included Visual Basic for Applications (VBA), a programming language based on Visual Basic which adds the ability to automate tasks in Excel and to provide user-defined functions (UDF) for use in worksheets. VBA includes a fully featured integrated development environment (IDE). Macro recording can produce VBA code replicating user actions, thus allowing simple automation of regular tasks. VBA allows the creation of forms and in‑worksheet controls to communicate with the user. The language supports use (but not creation) of ActiveX (COM) DLL's; later versions add support for class modules allowing the use of basic object-oriented programming techniques. | https://en.wikipedia.org/wiki?curid=20268 |
9,614 | The automation functionality provided by VBA made Excel a target for macro viruses. This caused serious problems until antivirus products began to detect these viruses. Microsoft belatedly took steps to prevent the misuse by adding the ability to disable macros completely, to enable macros when opening a workbook or to trust all macros signed using a trusted certificate. | https://en.wikipedia.org/wiki?curid=20268 |
9,615 | Versions 5.0 to 9.0 of Excel contain various Easter eggs, including a "Hall of Tortured Souls", a Doom-like minigame, although since version 10 Microsoft has taken measures to eliminate such undocumented features from their products. | https://en.wikipedia.org/wiki?curid=20268 |
9,616 | 5.0 was released in a 16-bit x86 version for Windows 3.1 and later in a 32-bit version for NT 3.51 (x86/Alpha/PowerPC) | https://en.wikipedia.org/wiki?curid=20268 |
9,617 | Released in 1995 with Microsoft Office for Windows 95, this is the first major version after Excel 5.0, as there is no Excel 6.0 with all of the Office applications standardizing on the same major version number. | https://en.wikipedia.org/wiki?curid=20268 |
9,618 | Included in Office 97 (for x86 and Alpha). This was a major upgrade that introduced the paper clip office assistant and featured standard VBA used instead of internal Excel Basic. It introduced the now-removed Natural Language labels. | https://en.wikipedia.org/wiki?curid=20268 |
9,619 | Included in Office 2000. This was a minor upgrade but introduced an upgrade to the clipboard where it can hold multiple objects at once. The Office Assistant, whose frequent unsolicited appearance in Excel 97 had annoyed many users, became less intrusive. | https://en.wikipedia.org/wiki?curid=20268 |
9,620 | Included in Office 2007. This release was a major upgrade from the previous version. Similar to other updated Office products, Excel in 2007 used the new Ribbon menu system. This was different from what users were used to, and was met with mixed reactions. One study reported fairly good acceptance by users except highly experienced users and users of word processing applications with a classical WIMP interface, but was less convinced in terms of efficiency and organization. However, an online survey reported that a majority of respondents had a negative opinion of the change, with advanced users being "somewhat more negative" than intermediate users, and users reporting a self-estimated reduction in productivity. | https://en.wikipedia.org/wiki?curid=20268 |
9,621 | Added functionality included the SmartArt set of editable business diagrams. Also added was an improved management of named variables through the "Name Manager", and much-improved flexibility in formatting graphs, which allow ("x, y") coordinate labeling and lines of arbitrary weight. Several improvements to pivot tables were introduced. | https://en.wikipedia.org/wiki?curid=20268 |
9,622 | Also like other office products, the Office Open XML file formats were introduced, including ".xlsm" for a workbook with macros and ".xlsx" for a workbook without macros. | https://en.wikipedia.org/wiki?curid=20268 |
9,623 | Specifically, many of the size limitations of previous versions were greatly increased. To illustrate, the number of rows was now 1,048,576 (2) and columns was 16,384 (2; the far-right column is XFD). This changes what is a valid "A1" reference versus a named range. This version made more extensive use of multiple cores for the calculation of spreadsheets; however, VBA macros are not handled in parallel and XLL add‑ins were only executed in parallel if they were thread-safe and this was indicated at registration. | https://en.wikipedia.org/wiki?curid=20268 |
9,624 | Included in Office 2010, this is the next major version after v12.0, as version number 13 was skipped. | https://en.wikipedia.org/wiki?curid=20268 |
9,625 | Microsoft no longer releases Office or Excel in discrete versions. Instead, features are introduced automatically over time using Windows Update. The version number remains 16.0. Thereafter only the approximate dates when features appear can now be given. | https://en.wikipedia.org/wiki?curid=20268 |
9,626 | Excel offers many user interface tweaks over the earliest electronic spreadsheets; however, the essence remains the same as in the original spreadsheet software, VisiCalc: the program displays cells organized in rows and columns, and each cell may contain data or a formula, with relative or absolute references to other cells. | https://en.wikipedia.org/wiki?curid=20268 |
9,627 | Excel 2.0 for Windows, which was modeled after its Mac GUI-based counterpart, indirectly expanded the installed base of the then-nascent Windows environment. Excel 2.0 was released a month before Windows 2.0, and the installed base of Windows was so low at that point in 1987 that Microsoft had to bundle a runtime version of Windows 1.0 with Excel 2.0. Unlike Microsoft Word, there never was a DOS version of Excel. | https://en.wikipedia.org/wiki?curid=20268 |
9,628 | Excel became the first spreadsheet to allow the user to define the appearance of spreadsheets (fonts, character attributes, and cell appearance). It also introduced intelligent cell re-computation, where only cells dependent on the cell being modified are updated (previous spreadsheet programs recomputed everything all the time or waited for a specific user command). Excel introduced auto-fill, the ability to drag and expand the selection box to automatically copy a cell or row contents to adjacent cells or rows, adjusting the copies intelligently by automatically incrementing cell references or contents. Excel also introduced extensive graphing capabilities. | https://en.wikipedia.org/wiki?curid=20268 |
9,629 | Because Excel is widely used, it has been attacked by hackers. While Excel is not directly exposed to the Internet, if an attacker can get a victim to open a file in Excel, and there is an appropriate security bug in Excel, then the attacker can gain control of the victim's computer. UK's GCHQ has a tool named TORNADO ALLEY with this purpose. | https://en.wikipedia.org/wiki?curid=20268 |
9,630 | The Chicxulub crater () is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore near the community of Chicxulub, after which it is named. It was formed slightly over 66 million years ago when a large asteroid, about in diameter, struck Earth. The crater is estimated to be in diameter and in depth. It is the second largest confirmed impact structure on Earth, and the only one whose peak ring is intact and directly accessible for scientific research. | https://en.wikipedia.org/wiki?curid=174609 |
9,631 | The crater was discovered by Antonio Camargo and Glen Penfield, geophysicists who had been looking for petroleum in the Yucatán Peninsula during the late 1970s. Penfield was initially unable to obtain evidence that the geological feature was a crater and gave up his search. Later, through contact with Alan R. Hildebrand in 1990, Penfield obtained samples that suggested it was an impact feature. Evidence for the crater's impact origin includes shocked quartz, a gravity anomaly, and tektites in surrounding areas. | https://en.wikipedia.org/wiki?curid=174609 |
9,632 | The date of the impact coincides with the Cretaceous–Paleogene boundary (commonly known as the K–Pg or K–T boundary). It is now widely accepted that the resulting devastation and climate disruption was the cause of the Cretaceous–Paleogene extinction event, a mass extinction of 75% of plant and animal species on Earth, including all non-avian dinosaurs. | https://en.wikipedia.org/wiki?curid=174609 |
9,633 | In the late 1970s, geologist Walter Alvarez and his father, Nobel Prize-winning scientist Luis Walter Alvarez, put forth their theory that the Cretaceous–Paleogene extinction was caused by an impact event. The main evidence of such an impact was contained in a thin layer of clay present in the Cretaceous–Paleogene boundary (K–Pg boundary) in Gubbio, Italy. The Alvarezes and colleagues reported that it contained an abnormally high concentration of iridium, a chemical element rare on Earth but common in asteroids. Iridium levels in this layer were as much as 160 times above the background level. It was hypothesized that the iridium was spread into the atmosphere when the impactor was vaporized and settled across Earth's surface among other material thrown up by the impact, producing the layer of iridium-enriched clay. At the time, there was no consensus on what caused the Cretaceous–Paleogene extinction and the boundary layer, with theories including a nearby supernova, climate change, or a geomagnetic reversal. The Alvarezes' impact hypothesis was rejected by many paleontologists, who believed that the lack of fossils found close to the K–Pg boundary—the "three-meter problem"—suggested a more gradual die-off of fossil species. | https://en.wikipedia.org/wiki?curid=174609 |
9,634 | The Alvarezes, joined by Frank Asaro and Helen Michel from University of California, Berkeley, published their paper on the iridium anomaly in "Science" in June 1980. Their paper was followed by other reports of similar iridium spikes at the K–Pg boundary across the globe, and sparked wide interest in the cause of the K–Pg extinction; over 2,000 papers were published in the 1980s on the topic. There were no known impact craters that were the right age and size, spurring a search for a suitable candidate. Recognizing the scope of the work, Lee Hunt and Lee Silver organized a cross-discipline meeting in Snowbird, Utah, in 1981. Unknown to them, evidence of the crater they were looking for was being presented the same week, and would be largely missed by the scientific community. | https://en.wikipedia.org/wiki?curid=174609 |
9,635 | In 1978, geophysicists Glen Penfield and Antonio Camargo were working for the Mexican state-owned oil company Petróleos Mexicanos (Pemex) as part of an airborne magnetic survey of the Gulf of Mexico north of the Yucatán Peninsula. Penfield's job was to use geophysical data to scout possible locations for oil drilling. In the offshore magnetic data, Penfield noted anomalies whose depth he estimated and mapped. He then obtained onshore gravity data from the 1940s. When the gravity maps and magnetic anomalies were compared, Penfield described a shallow "bullseye", in diameter, appearing on the otherwise non-magnetic and uniform surroundings—clear evidence to him of an impact feature. A decade earlier, the same map had suggested a crater to contractor Robert Baltosser, but Pemex corporate policy prevented him from publicizing his conclusion. | https://en.wikipedia.org/wiki?curid=174609 |
9,636 | Penfield presented his findings to Pemex, who rejected the crater theory, instead deferring to findings that ascribed the feature to volcanic activity. Pemex disallowed release of specific data, but let Penfield and Camargo present the results at the 1981 Society of Exploration Geophysicists conference. That year's conference was under-attended and their report attracted scant attention, with many experts on impact craters and the K–Pg boundary attending the Snowbird conference instead. Carlos Byars, a "Houston Chronicle" journalist who was familiar with Penfield and had seen the gravitational and magnetic data himself, wrote a story on Penfield and Camargo's claim, but the news did not disseminate widely. | https://en.wikipedia.org/wiki?curid=174609 |
9,637 | Although Penfield had plenty of geophysical data sets, he had no rock cores or other physical evidence of an impact. He knew Pemex had drilled exploratory wells in the region. In 1951, one bored into what was described as a thick layer of andesite about down. This layer could have resulted from the intense heat and pressure of an Earth impact, but at the time of the borings it was dismissed as a lava dome—a feature uncharacteristic of the region's geology. Penfield was encouraged by William C. Phinney, curator of the lunar rocks at the Johnson Space Center, to find these samples to support his hypothesis. Penfield tried to secure site samples, but was told they had been lost or destroyed. When attempts to return to the drill sites to look for corroborating rocks proved fruitless, Penfield abandoned his search, published his findings and returned to his Pemex work. Seeing the 1980 "Science" paper, Penfield wrote to Walter Alvarez about the Yucatán structure, but received no response. | https://en.wikipedia.org/wiki?curid=174609 |
9,638 | Alvarez and other scientists continued their search for the crater, although they were searching in oceans based on incorrect analysis of glassy spherules from the K–Pg boundary that suggested the impactor had landed in open water. Unaware of Penfield's discovery, University of Arizona graduate student Alan R. Hildebrand and faculty adviser William V. Boynton looked for a crater near the Brazos River in Texas. Their evidence included greenish-brown clay with surplus iridium, containing shocked quartz grains and small weathered glass beads that looked to be tektites. Thick, jumbled deposits of coarse rock fragments were also present, thought to have been scoured from one place and deposited elsewhere by an impact event. Such deposits occur in many locations but seemed concentrated in the Caribbean Basin at the K–Pg boundary. When Haitian professor Florentine Morás discovered what he thought to be evidence of an ancient volcano on Haiti, Hildebrand suggested it could be a telltale feature of a nearby impact. Tests on samples retrieved from the K–Pg boundary revealed more tektite glass, formed only in the heat of asteroid impacts and high-yield nuclear detonations. | https://en.wikipedia.org/wiki?curid=174609 |
9,639 | In 1990, Carlos Byars told Hildebrand of Penfield's earlier discovery of a possible impact crater. Hildebrand contacted Penfield and the pair soon secured two drill samples from the Pemex wells, which had been stored in New Orleans for decades. Hildebrand's team tested the samples, which clearly showed shock-metamorphic materials. A team of California researchers surveying satellite images found a cenote (sinkhole) ring centered on the town of Chicxulub Puerto that matched the one Penfield saw earlier; the cenotes were thought to be caused by subsidence of bolide-weakened lithostratigraphy around the impact crater wall. More recent evidence suggests the crater is wide, and the ring is an inner wall of it. Hildebrand, Penfield, Boynton, Camargo, and others published their paper identifying the crater in 1991. The crater was named for the nearby town of Chicxulub. Penfield also recalled that part of the motivation for the name was "to give the academics and NASA naysayers a challenging time pronouncing it" after years of dismissing its existence. | https://en.wikipedia.org/wiki?curid=174609 |
9,640 | In March 2010, forty-one experts from many countries reviewed the available evidence: twenty years' worth of data spanning a variety of fields. They concluded that the impact at Chicxulub triggered the mass extinctions at the K–Pg boundary. Dissenters, notably Gerta Keller of Princeton University, have proposed an alternate culprit: the eruption of the Deccan Traps in what is now the Indian subcontinent. This period of intense volcanism occurred before and after the Chicxulub impact; dissenting studies argue that the worst of the volcanic activity occurred "before" the impact, and the role of the Deccan Traps was instead shaping the evolution of surviving species post-impact. A 2013 study compared isotopes in impact glass from the Chicxulub impact with isotopes in ash from the K–Pg boundary, concluding that they were dated almost exactly the same within experimental error. | https://en.wikipedia.org/wiki?curid=174609 |
9,641 | A 2013 study published in "Science" estimated the age of the impact as 66,043,000 ± 11,000 years ago (± 43,000 years ago considering systematic error), based on multiple lines of evidence, including argon–argon dating of tektites from Haiti and bentonite horizons overlying the impact horizon in northeastern Montana, United States. This date was supported by a 2015 study based on argon–argon dating of tephra found in lignite beds in the Hell Creek and overlying Fort Union formations in northeastern Montana. A 2018 study based on argon–argon dating of spherules from Gorgonilla Island, Colombia, obtained a slightly different result of 66,051,000 ± 31,000 years ago. The impact has been interpreted to have occurred in Northern Hemisphere spring based on annual isotope curves in sturgeon and paddlefish bones found in an ejecta-bearing sedimentary unit at the Tanis site in southwestern North Dakota. This sedimentary unit is thought to have formed within hours of impact. A 2020 study concluded that the Chicxulub crater was formed by an inclined (45–60° to horizontal) impact from the northeast. The site of the crater at the time of impact was a marine carbonate platform. The water depth at the impact site varied from on the western edge of the crater to over on the northeastern edge. The seafloor rocks consisted of a sequence of Jurassic–Cretaceous marine sediments, thick. They were predominantly carbonate rock, including dolomite (35–40% of total sequence) and limestone (25–30%), along with evaporites (anhydrite 25–30%), and minor amounts of shale and sandstone (3–4%) underlain by approximately of continental crust, composed of igneous crystalline basement including granite. | https://en.wikipedia.org/wiki?curid=174609 |
9,642 | There is broad consensus that the Chicxulub impactor was an asteroid with a carbonaceous chondrite composition, rather than a comet. In 1998, a meteorite was described from the North Pacific from sediments spanning the Cretaceous–Paleogene boundary; it was suggested to represent a fragment of the Chicxulub impactor. Analysis suggested that it best fitted the criteria of the CV, CO and CR groups of carbonaceous chondrites. A 2021 paper suggested, based on geochemical evidence including the excess of chromium isotope Cr and the ratios of platinum group metals found in marine impact layers, that the impactor was either a CM or CR carbonaceous chondrite C-type asteroid. The impactor was around in diameter—large enough that, if set at sea level, it would have reached taller than Mount Everest. | https://en.wikipedia.org/wiki?curid=174609 |
9,643 | The impactor's velocity was estimated at . The kinetic energy of the impact was estimated at . The impact created winds in excess of near the blast's center, and created a transient cavity wide and deep that later collapsed. This formed a crater mainly under the sea and covered by of sediment by the 21st century. The impact, expansion of water after filling the crater, and related seismic activity spawned megatsunamis over tall, with one simulation suggesting the immediate waves from the impact may have reached up to high. The waves scoured the sea floor, leaving ripples underneath what is now Louisiana with average wavelengths of and average wave heights of , the largest ripples documented. Material shifted by subsequent earthquakes and the waves reached to what are now Texas and Florida, and may have disturbed sediments as far as from the impact site. The impact triggered a seismic event with an estimated magnitude of 9–11 at the impact site. | https://en.wikipedia.org/wiki?curid=174609 |
9,644 | A cloud of hot dust, ash and steam would have spread from the crater, with as much as 25 trillion metric tons of excavated material being ejected into the atmosphere by the blast. Some of this material escaped orbit, dispersing throughout the Solar System, while some of it fell back to Earth, heated to incandescence upon re-entry. The rock heated Earth's surface and ignited wildfires, estimated to have enveloped nearly 70% of the planet's forests. The devastation to living creatures even hundreds of kilometers away was immense, and much of present-day Mexico and the United States would have been devastated. Fossil evidence for an instantaneous extinction of diverse animals was found in a soil layer only thick in New Jersey, away from the impact site, indicating that death and burial under debris occurred suddenly and quickly over wide distances on land. Field research from the Hell Creek Formation in North Dakota published in 2019 shows the simultaneous mass extinction of myriad species combined with geological and atmospheric features consistent with the impact event. | https://en.wikipedia.org/wiki?curid=174609 |
9,645 | Due to the relatively shallow water, the rock that was vaporized included sulfur-rich gypsum from the lower part of the Cretaceous sequence, and this was injected into the atmosphere. This global dispersal of dust and sulfates would have led to a sudden and catastrophic effect on the climate worldwide, instigating large temperature drops and devastating the food chain. The researchers stated that the impact generated an environmental calamity that extinguished life, but it also induced a vast subsurface hydrothermal system that became an oasis for the recovery of life. Researchers using seismic images of the crater in 2008 determined that the impactor landed in deeper water than previously assumed, which may have resulted in increased sulfate aerosols in the atmosphere, due to more water vapor being available to react with the vaporized anhydrite. This could have made the impact even deadlier by cooling the climate and generating acid rain. | https://en.wikipedia.org/wiki?curid=174609 |
9,646 | The emission of dust and particles could have covered the entire surface of Earth for several years, possibly a decade, creating a harsh environment for living things. Production of carbon dioxide caused by the destruction of carbonate rocks would have led to a sudden greenhouse effect. Over a decade or longer, sunlight would have been blocked from reaching the surface of Earth by the dust particles in the atmosphere, cooling the surface dramatically. Photosynthesis by plants would also have been interrupted, affecting the entire food chain. A model of the event developed by Lomax et al (2001) suggests that net primary productivity rates may have increased to higher than pre-impact levels over the long term because of the high carbon dioxide concentrations. | https://en.wikipedia.org/wiki?curid=174609 |
9,647 | A long-term local effect of the impact was the creation of the Yucatán sedimentary basin which "ultimately produced favorable conditions for human settlement in a region where surface water is scarce". | https://en.wikipedia.org/wiki?curid=174609 |
9,648 | Two seismic reflection datasets have been acquired over the offshore parts of the crater since its discovery. Older 2D seismic datasets have also been used that were originally acquired for hydrocarbon exploration. A set of three long-record 2D lines was acquired in October 1996, with a total length of , by the BIRPS group. The longest of the lines, Chicx-A, was shot parallel to the coast, while Chicx-B and Chicx-C were shot NW–SE and SSW–NNE respectively. In addition to the conventional seismic reflection imaging, data was recorded onshore to allow wide-angle refraction imaging. | https://en.wikipedia.org/wiki?curid=174609 |
9,649 | In 2005, another set of profiles was acquired, bringing the total length of 2D deep-penetration seismic data up to . This survey also used ocean bottom seismometers and land stations to allow 3D travel time inversion to improve the understanding of the velocity structure of the crater. The data was concentrated around the interpreted offshore peak ring to help identify possible drilling locations. At the same time, gravity data were acquired along of profiles. The acquisition was funded by the National Science Foundation (NSF), Natural Environment Research Council (NERC) with logistical assistance from the National Autonomous University of Mexico (UNAM) and the Centro de Investigación Científica de Yucatán (CICY – Yucatán Center for Scientific Investigation). | https://en.wikipedia.org/wiki?curid=174609 |
9,650 | Intermittent core samples from hydrocarbon exploration boreholes drilled by Pemex on the Yucatán peninsula have provided some useful data. UNAM drilled a series of eight fully-cored boreholes in 1995, three of which penetrated deeply enough to reach the ejecta deposits outside the main crater rim, UNAM-5, 6 and 7. In 2001–2002, a scientific borehole was drilled near the Hacienda Yaxcopoil, known as Yaxcopoil-1 (or more commonly Yax-1), to a depth of below the surface, as part of the International Continental Scientific Drilling Program. The borehole was cored continuously, passing through of impactites. Three fully-cored boreholes were also drilled by the Comisión Federal de Electricidad (Federal Electricity Commission) with UNAM. One of them, (BEV-4), was deep enough to reach the ejecta deposits. | https://en.wikipedia.org/wiki?curid=174609 |
9,651 | In 2016, a joint United Kingdom–United States team obtained the first offshore core samples, from the peak ring in the central zone of the crater with the drilling of the borehole known as M0077A, part of Expedition 364 of the International Ocean Discovery Program. The borehole reached below the seafloor. | https://en.wikipedia.org/wiki?curid=174609 |
9,652 | The form and structure (morphology) of the Chicxulub crater is known mainly from geophysical data. It has a well-defined concentric multi-ring structure. The outermost ring was identified using seismic reflection data. It is up to from the crater center, and is a ring of normal faults, throwing down towards the crater center, marking the outer limit of significant crustal deformation. This makes it one of the three largest impact structures on Earth. Moving into the center, the next ring is the main crater rim, also known as the "inner rim" which correlates with ring of cenotes onshore and a major circular Bouguer gravity gradient anomaly. This has a radius that varies between . The next ring structure, moving inwards, is the peak ring. The area between the inner rim and peak ring is described as the "terrace zone", characterized by a series of fault blocks defined by normal faults dipping towards the crater center, sometimes referred to as "slump blocks". The peak ring is about 80 km in diameter and of variable height, from above the base of the crater in the west and northwest and in the north, northeast and east. The central part of the crater lies above a zone where the mantle was uplifted such that the Moho is shallower by about compared to regional values. | https://en.wikipedia.org/wiki?curid=174609 |
9,653 | The ring structures are best developed to the south, west and northwest, becoming more indistinct towards the north and northeast of the structure. This is interpreted to be a result of variable water depth at the time of impact, with less well-defined rings resulting from the areas with water depths significantly deeper than . | https://en.wikipedia.org/wiki?curid=174609 |
9,654 | Before the impact, the geology of the Yucatán area, sometimes referred to as the "target rocks", consisted of a sequence of mainly Cretaceous limestones, overlying red beds of uncertain age above an unconformity with the dominantly granitic basement. The basement forms part of the Maya Block and information about its makeup and age in the Yucatán area has come only from drilling results around the Chicxulub crater and the analysis of basement material found as part of the ejecta at more distant K–Pg boundary sites. The Maya block is one of a group of crustal blocks found at the edge of the Gondwana continent. Zircon ages are consistent with the presence of an underlying Grenville age crust, with large amounts of late Ediacaran arc-related igneous rocks, interpreted to have formed in the Pan-African orogeny. Late Paleozoic granitoids (the distinctive "pink granite") were found in the peak ring borehole M0077A, with an estimated age of 326 ± 5 million years ago (Carboniferous). These have an adakitic composition and are interpreted to represent the effects of slab detachment during the Marathon-Ouachita orogeny, part of the collision between Laurentia and Gondwana that created the Pangaea supercontinent. | https://en.wikipedia.org/wiki?curid=174609 |
9,655 | Red beds of variable thickness, up to , overlay the granitic basement, particularly in the southern part of the area. These continental clastic rocks are thought to be of Triassic-to-Jurassic age, although they may extend into the Lower Cretaceous. The lower part of the Lower Cretaceous sequence consists of dolomite with interbedded anhydrite and gypsum, with the upper part being limestone, with dolomite and anhydrite in part. The thickness of the Lower Cretaceous varies from up to in the boreholes. The Upper Cretaceous sequence is mainly platform limestone, with marl and interbedded anhydrite. It varies in thickness from up to . There is evidence for a Cretaceous basin within the Yucatán area that has been named the Yucatán Trough, running approximately south–north, widening northwards, explaining the observed thickness variations. | https://en.wikipedia.org/wiki?curid=174609 |
9,656 | The most common observed impact rocks are suevites, found in many of the boreholes drilled around the Chicxulub crater. Most of the suevites were resedimented soon after the impact by the resurgence of oceanic water into the crater. This gave rise to a layer of suevite extending from the inner part of the crater out as far as the outer rim. | https://en.wikipedia.org/wiki?curid=174609 |
9,657 | Impact melt rocks are thought to fill the central part of the crater, with a maximum thickness of . The samples of melt rock that have been studied have overall compositions similar to that of the basement rocks, with some indications of mixing with carbonate source, presumed to be derived from the Cretaceous carbonates. An analysis of melt rocks sampled by the M0077A borehole indicates two types of melt rock, an upper impact melt (UIM), which has a clear carbonate component as shown by its overall chemistry and the presence of rare limestone clasts and a lower impact melt-bearing unit (LIMB) that lacks any carbonate component. The difference between the two impact melts is interpreted to be a result of the upper part of the initial impact melt, represented by the LIMB in the borehole, becoming mixed with materials from the shallow part of the crust either falling back into the crater or being brought back by the resurgence forming the UIM. | https://en.wikipedia.org/wiki?curid=174609 |
9,658 | The "pink granite", a granitoid rich in alkali feldspar found in the peak ring borehole shows many deformation features that record the extreme strains associated with the formation of the crater and the subsequent development of the peak ring. The granitoid has an unusually low density and P-wave velocity compared to typical granitic basement rocks. Study of the core from M0077A shows the following deformation features in apparent order of development: pervasive fracturing along and through grain boundaries, a high density of shear faults, bands of cataclasite and ultra-cataclasite and some ductile shear structures. This deformation sequence is interpreted to result from initial crater formation involving acoustic fluidization followed by shear faulting with the development of cataclasites with fault zones containing impact melts. | https://en.wikipedia.org/wiki?curid=174609 |
9,659 | The peak ring drilling below the sea floor also discovered evidence of a massive hydrothermal system, which modified approximately of Earth's crust and lasted for hundreds of thousands of years. These hydrothermal systems may provide support for the impact origin of life hypothesis for the Hadean eon, when the entire surface of Earth was affected by impactors much larger than the Chicxulub impactor. | https://en.wikipedia.org/wiki?curid=174609 |
9,660 | After the immediate effects of the impact had stopped, sedimentation in the Chicxulub area returned to the shallow water platform carbonate depositional environment that characterised it before the impact. The sequence, which dates back as far as the Paleocene, consists of marl and limestone, reaching a thickness of about . The K–Pg boundary inside the crater is significantly deeper than in the surrounding area. | https://en.wikipedia.org/wiki?curid=174609 |
9,661 | On the Yucatán peninsula, the inner rim of the crater is marked by clusters of cenotes, which are the surface expression of a zone of preferential groundwater flow, moving water from a recharge zone in the south to the coast through a karstic aquifer system. From the cenote locations, the karstic aquifer is clearly related to the underlying crater rim, possibly through higher levels of fracturing, | https://en.wikipedia.org/wiki?curid=174609 |
9,662 | In September 2007, a report published in "Nature" proposed an origin for the asteroid that created the Chicxulub crater. The authors, William F. Bottke, David Vokrouhlický, and David Nesvorný, argued that a collision in the asteroid belt 160 million years ago between a 170 km (106 mi) diameter parent body and another 60 km (37 mi) diameter body, resulted in the Baptistina family of asteroids, the largest surviving member of which is 298 Baptistina. They proposed that the "Chicxulub asteroid" was also a member of this group. | https://en.wikipedia.org/wiki?curid=174609 |
9,663 | The Baptistina family is not considered a likely source of the Chicxulub asteroid because a spectrographic analysis published in 2009 revealed that 298 Baptistina has a different composition more typical of an S-type asteroid than the presumed carbonaceous chondrite composition of the Chicxulub impactor. In 2011, data from the Wide-field Infrared Survey Explorer revised the date of the collision which created the Baptistina family to about 80 million years ago. This made an asteroid from this family highly improbable to be the asteroid that created the Chicxulub crater, as typically the process of resonance and collision of an asteroid takes many tens of millions of years. In 2010, another hypothesis implicated the newly discovered asteroid 354P/LINEAR, a member of the Flora family of asteroids, as a possible remnant cohort of the K–Pg impactor. In July 2021, a study reported that the impactor likely originated in the outer main part of the asteroid belt, based on numerical simulations. | https://en.wikipedia.org/wiki?curid=174609 |
9,664 | The original 1980 paper describing the crater suggested that it was created by an asteroid around in diameter. Two papers published in 1984 proposed the impactor to be a comet originating from the Oort cloud, and it was proposed in 1992 that tidal disruption of comets could potentially increase impact rates. In February 2021, four independent laboratories reported elevated concentrations of iridium in the crater's peak ring, further corroborating the asteroid impact hypothesis. In the same month, Avi Loeb and a colleague published a study in "Scientific Reports" suggesting the impactor was a fragment from a disrupted comet, rather than an asteroid—the long-standing leading candidate among scientists. This was followed by a rebuttal published in "Astronomy & Geophysics" that June, which charged that the paper ignored the fact that the mass of iridium deposited across the globe by the impact (estimated to be approximately 2.0–2.8 × 10 grams), was too large to be created by a comet impactor the size required to create the crater, and that Loeb et al. had overestimated likely comet impact rates. They found that an asteroid impactor was strongly favored by all available evidence, and that a comet impactor could be effectively ruled out. | https://en.wikipedia.org/wiki?curid=174609 |
9,665 | The Battle of Midway was a major naval battle in the Pacific Theater of World War II that took place on 4–7 June 1942, six months after Japan's attack on Pearl Harbor and one month after the Battle of the Coral Sea. The U.S. Navy under Admirals Chester W. Nimitz, Frank J. Fletcher, and Raymond A. Spruance defeated an attacking fleet of the Imperial Japanese Navy under Admirals Isoroku Yamamoto, Chūichi Nagumo, and Nobutake Kondō north of Midway Atoll, inflicting devastating damage on the Japanese fleet. Military historian John Keegan called it "the most stunning and decisive blow in the history of naval warfare", while naval historian Craig Symonds called it "one of the most consequential naval engagements in world history, ranking alongside Salamis, Trafalgar, and Tsushima Strait, as both tactically decisive and strategically influential". | https://en.wikipedia.org/wiki?curid=60112 |
9,666 | Hoping to lure the American aircraft carriers into a trap and occupying Midway was part of an overall "barrier" strategy to extend Japan's defensive perimeter, in response to the Doolittle air raid on Tokyo. This operation was also considered preparatory for further attacks against Fiji, Samoa, and Hawaii itself. The plan was undermined by faulty Japanese assumptions of the American reaction and poor initial dispositions. Most significantly, American cryptographers were able to determine the date and location of the planned attack, enabling the forewarned U.S. Navy to prepare its own ambush. | https://en.wikipedia.org/wiki?curid=60112 |
9,667 | Four Japanese and three American aircraft carriers participated in the battle. The four Japanese fleet carriers—, , , and , part of the six-carrier force that had attacked Pearl Harbor six months earlier—were sunk, as was the heavy cruiser . The U.S. lost the carrier and the destroyer , while the carriers and survived the battle fully intact. | https://en.wikipedia.org/wiki?curid=60112 |
9,668 | After Midway and the exhausting attrition of the Solomon Islands campaign, Japan's capacity to replace its losses in materiel (particularly aircraft carriers) and men (especially well-trained pilots and maintenance crewmen) rapidly became insufficient to cope with mounting casualties, while the United States' massive industrial and training capabilities made losses far easier to replace. The Battle of Midway, along with the Guadalcanal campaign, is widely considered a turning point in the Pacific War. | https://en.wikipedia.org/wiki?curid=60112 |
9,669 | After expanding the war in the Pacific to include Western outposts, the Japanese Empire had attained its initial strategic goals quickly, taking British Hong Kong, the Philippines, British Malaya, Singapore, and the Dutch East Indies (modern Indonesia). The latter, with its vital oil resources, was particularly important to Japan. Because of this, preliminary planning for the second phase of operations commenced as early as January 1942. | https://en.wikipedia.org/wiki?curid=60112 |
9,670 | Because of strategic disagreements between the Imperial Army (IJA) and Imperial Navy (IJN), and infighting between the Navy's GHQ and Admiral Isoroku Yamamoto's Combined Fleet, a follow-up strategy was not formed until April 1942. Admiral Yamamoto finally won the bureaucratic struggle with a thinly veiled threat to resign, after which his plan for the Central Pacific was adopted. | https://en.wikipedia.org/wiki?curid=60112 |
9,671 | Yamamoto's primary strategic goal was the elimination of America's carrier forces, which he regarded as the principal threat to the overall Pacific campaign. This concern was acutely heightened by the Doolittle Raid on 18 April 1942, in which 16 United States Army Air Forces (USAAF) B-25 Mitchell bombers launched from bombed targets in Tokyo and several other Japanese cities. The raid, while militarily insignificant, was a shock to the Japanese and showed the existence of a gap in the defenses around the Japanese home islands as well as the vulnerability of Japanese territory to American bombers. | https://en.wikipedia.org/wiki?curid=60112 |
9,672 | This, and other successful hit-and-run raids by American carriers in the South Pacific, showed that they were still a threat, although seemingly reluctant to be drawn into an all-out battle. Yamamoto reasoned that another air attack on the main U.S. naval base at Pearl Harbor would induce all of the American fleet to sail out to fight, including the carriers. However, considering the increased strength of American land-based airpower on the Hawaiian Islands since the 7 December attack the previous year, he judged that it was now too risky to attack Pearl Harbor directly. | https://en.wikipedia.org/wiki?curid=60112 |
9,673 | Instead, Yamamoto selected Midway, a tiny atoll at the extreme northwest end of the Hawaiian Island chain, approximately from Oahu. This meant that Midway was outside the effective range of almost all of the American aircraft stationed on the main Hawaiian islands. Midway was not especially important in the larger scheme of Japan's intentions, but the Japanese felt the Americans would consider Midway a vital outpost of Pearl Harbor and would therefore be compelled to defend it vigorously. The U.S. did consider Midway vital: after the battle, the establishment of a U.S. submarine base on Midway allowed submarines operating from Pearl Harbor to refuel and re-provision, extending their radius of operations by . In addition to serving as a seaplane base, Midway's airstrips also served as a forward staging point for bomber attacks on Wake Island. | https://en.wikipedia.org/wiki?curid=60112 |
9,674 | Typical of Japanese naval planning during World War II, Yamamoto's battle plan for taking Midway (named Operation MI) was exceedingly complex. It required the careful and timely coordination of multiple battle groups over hundreds of miles of open sea. His design was also predicated on optimistic intelligence suggesting that and USS "Hornet", forming Task Force 16, were the only carriers available to the U.S. Pacific Fleet. During the Battle of the Coral Sea one month earlier, had been sunk and suffered so much damage that the Japanese believed she too had been lost. However, following hasty repairs at Pearl Harbor, "Yorktown" sortied and ultimately played a critical role in the discovery and eventual destruction of the Japanese fleet carriers at Midway. Finally, much of Yamamoto's planning, coinciding with the general feeling among the Japanese leadership at the time, was based on a gross misjudgment of American morale, which was believed to be debilitated from the string of Japanese victories in the preceding months. | https://en.wikipedia.org/wiki?curid=60112 |
9,675 | Yamamoto felt deception would be required to lure the U.S. fleet into a fatally compromised situation. To this end, he dispersed his forces so that their full extent (particularly his battleships) would be concealed from the Americans prior to battle. Critically, Yamamoto's supporting battleships and cruisers trailed Vice Admiral Chūichi Nagumo's carrier force by several hundred miles. They were intended to come up and destroy whatever elements of the U.S. fleet might come to Midway's defense once Nagumo's carriers had weakened them sufficiently for a daylight gun battle. This tactic was doctrine in most major navies of the time. | https://en.wikipedia.org/wiki?curid=60112 |
9,676 | What Yamamoto did not know was that the U.S. had broken parts of the main Japanese naval code (dubbed JN-25 by the Americans), divulging many details of his plan to the enemy. His emphasis on dispersal also meant none of his formations were in a position to support the others. For instance, despite the fact that Nagumo's carriers were expected to carry out strikes against Midway and bear the brunt of American counterattacks, the only warships in his fleet larger than the screening force of twelve destroyers were two "Kongō"-class fast battleships, two heavy cruisers, and one light cruiser. By contrast, Yamamoto and Kondo had between them two light carriers, five battleships, four heavy cruisers, and two light cruisers, none of which saw action at Midway. The light carriers of the trailing forces and Yamamoto's three battleships were unable to keep pace with the carriers of the "Kidō Butai" and so could not have sailed in company with them. The Kido Butai would sail into range at best speed so as to increase the chance of surprise, and would not have ships spread out across the ocean guiding the enemy toward it. If the other parts of the invasion force needed more defense, the Kido Butai would make best speed to defend them. Hence the slower ships could not be with the Kido Butai. The distance between Yamamoto and Kondo's forces and Nagumo's carriers had grave implications during the battle. The invaluable reconnaissance capability of the scout planes carried by the cruisers and carriers, as well as the additional antiaircraft capability of the cruisers and the other two battleships of the "Kongō"-class in the trailing forces, was unavailable to Nagumo. | https://en.wikipedia.org/wiki?curid=60112 |
9,677 | In order to obtain support from the Imperial Japanese Army for the Midway operation, the Imperial Japanese Navy agreed to support their invasion of the United States through the Aleutian Islands of Attu and Kiska, part of the organized incorporated Alaska Territory. The IJA occupied these islands to place the Japanese home islands out of range of U.S. land-based bombers in Alaska. Similarly, most Americans feared that the occupied islands would be used as bases for Japanese bombers to attack strategic targets and population centers along the West Coast of the United States. The Japanese operations in the Aleutians (Operation AL) removed yet more ships that could otherwise have augmented the force striking Midway. Whereas many earlier historical accounts considered the Aleutians operation as a feint to draw American forces away, according to the original Japanese battle plan, AL was intended to be launched simultaneously with the attack on Midway. A one-day delay in the sailing of Nagumo's task force resulted in Operation AL beginning a day before the Midway attack. | https://en.wikipedia.org/wiki?curid=60112 |
9,678 | To do battle with an enemy expected to muster four or five carriers, Admiral Chester W. Nimitz, Commander in Chief, Pacific Ocean Areas, needed every available flight deck. He already had Vice Admiral William Halsey's two-carrier ("Enterprise" and "Hornet") task force at hand, though Halsey was stricken with shingles and had to be replaced by Rear Admiral Raymond A. Spruance, Halsey's escort commander. Nimitz also hurriedly recalled Rear Admiral Frank Jack Fletcher's task force, including the carrier "Yorktown", from the South West Pacific Area. | https://en.wikipedia.org/wiki?curid=60112 |
9,679 | Despite estimates that "Yorktown", damaged in the Battle of the Coral Sea, would require several months of repairs at Puget Sound Naval Shipyard, her elevators were intact and her flight deck largely so. The Pearl Harbor Naval Shipyard worked around the clock, and in 72 hours she was restored to a battle-ready state, judged good enough for two or three weeks of operations, as Nimitz required. Her flight deck was patched, and whole sections of internal frames were cut out and replaced. Repairs continued even as she sortied, with work crews from the repair ship , herself damaged in the attack on Pearl Harbor six months earlier, still aboard. | https://en.wikipedia.org/wiki?curid=60112 |
9,680 | "Yorktown"s partially depleted air group was rebuilt using whatever planes and pilots could be found. Scouting Five (VS-5) was replaced with Bombing Three (VB-3) from . Torpedo Five (VT-5) was also replaced by Torpedo Three (VT-3). Fighting Three (VF-3) was reconstituted to replace VF-42 with sixteen pilots from VF-42 and eleven pilots from VF-3, with Lieutenant Commander John S. "Jimmy" Thach in command. Some of the aircrew were inexperienced, which may have contributed to an accident in which Thach's executive officer Lieutenant Commander Donald Lovelace was killed. Despite efforts to get "Saratoga" (which had been undergoing repairs on the American West Coast) ready, the need to resupply and assemble sufficient escorts meant she was unable to reach Midway until after the battle. | https://en.wikipedia.org/wiki?curid=60112 |
9,681 | On Midway, by 4 June the U.S. Navy had stationed four squadrons of PBYs—31 aircraft in total—for long-range reconnaissance duties, and six brand-new Grumman TBF Avengers from "Hornet"s VT-8. The Marine Corps stationed 19 Douglas SBD Dauntless, seven F4F-3 Wildcats, 17 Vought SB2U Vindicators, and 21 Brewster F2A Buffalos. The USAAF contributed a squadron of 17 B-17 Flying Fortresses and four Martin B-26 Marauders equipped with torpedoes: in total 126 aircraft. Although the F2As and SB2Us were already obsolete, they were the only aircraft available to the Marine Corps at the time. | https://en.wikipedia.org/wiki?curid=60112 |
9,682 | During the Battle of the Coral Sea one month earlier, the Japanese light carrier had been sunk, while the fleet carrier had been severely damaged by three bomb hits and was in drydock for months of repair. Although the fleet carrier escaped the battle undamaged, she had lost almost half her air group, and was in port in Kure awaiting replacement planes and pilots. That there were none immediately available is attributable to the failure of the IJN crew training program, which already showed signs of being unable to replace losses. Instructors from the Yokosuka Air Corps were employed in an effort to make up the shortfall. | https://en.wikipedia.org/wiki?curid=60112 |
9,683 | Historians Jonathan Parshall and Anthony Tully believe that by combining the surviving aircraft and pilots from "Shōkaku" and "Zuikaku", it is likely that "Zuikaku" could have been equipped with almost a full composite air group. They also note, however, that doing so would have violated Japanese carrier doctrine, which stressed that carriers and their air groups must train as a single unit. (In contrast, American air squadrons were considered interchangeable between carriers.) In any case, the Japanese apparently made no serious attempt to get "Zuikaku" ready for the forthcoming battle. | https://en.wikipedia.org/wiki?curid=60112 |
9,684 | Thus, Carrier Division 5, consisting of the two most advanced aircraft carriers of the "Kido Butai", was not available, which meant that Vice-Admiral Nagumo had only two-thirds of the fleet carriers at his disposal: and forming Carrier Division 1 and and making up Carrier Division 2. This was partly due to fatigue; Japanese carriers had been constantly on operations since 7 December 1941, including raids on Darwin and Colombo. Nonetheless, the First Carrier Strike Force sailed with 248 available aircraft on the four carriers (60 on "Akagi", 74 on "Kaga" (B5N2 squadron oversized), 57 on "Hiryū" and 57 on "Sōryū"). | https://en.wikipedia.org/wiki?curid=60112 |
9,685 | The main Japanese carrier-borne strike aircraft were the D3A1 "Val" dive bomber and the B5N2 "Kate", which was used either as a torpedo bomber or as a level bomber. The main carrier fighter was the fast and highly maneuverable A6M "Zero". For a variety of reasons, production of the "Val" had been drastically reduced, while that of the "Kate" had been stopped completely and, as a consequence, there were none available to replace losses. In addition, many of the aircraft being used during the June 1942 operations had been operational since late November 1941 and, although they were well-maintained, many were almost worn out and had become increasingly unreliable. These factors meant all carriers of the "Kido Butai" had fewer aircraft than their normal complement, with few spare aircraft or parts stored in the carriers' hangars. | https://en.wikipedia.org/wiki?curid=60112 |
9,686 | In addition, Nagumo's carrier force suffered from several defensive deficiencies which gave it, in Mark Peattie's words, a glass jaw': it could throw a punch but couldn't take one." Japanese carrier anti-aircraft guns and associated fire control systems had several design and configuration deficiencies which limited their effectiveness. The IJN's fleet combat air patrol (CAP) consisted of too few fighter aircraft and was hampered by an inadequate early warning system, including a lack of radar. Poor radio communications with the fighter aircraft inhibited effective command and control of the CAP. The carriers' escorting warships were deployed as visual scouts in a ring at long range, not as close anti-aircraft escorts, as they lacked training, doctrine, and sufficient anti-aircraft guns. | https://en.wikipedia.org/wiki?curid=60112 |
9,687 | Japanese strategic scouting arrangements prior to the battle were also in disarray. A picket line of Japanese submarines was late getting into position (partly because of Yamamoto's haste), which let the American carriers reach their assembly point northeast of Midway (known as "Point Luck") without being detected. A second attempt at reconnaissance, using four-engine H8K "Emily" flying boats to scout Pearl Harbor prior to the battle and detect whether the American carriers were present, part of Operation K, was thwarted when Japanese submarines assigned to refuel the search aircraft discovered that the intended refueling point—a hitherto deserted bay off French Frigate Shoals—was now occupied by American warships because the Japanese had carried out an identical mission in March. Thus, Japan was deprived of any knowledge concerning the movements of the American carriers immediately before the battle. | https://en.wikipedia.org/wiki?curid=60112 |
9,688 | Japanese radio intercepts did notice an increase in both American submarine activity and message traffic. This information was in Yamamoto's hands prior to the battle. Japanese plans were not changed; Yamamoto, at sea in , assumed Nagumo had received the same signal from Tokyo, and did not communicate with him by radio, so as not to reveal his position. These messages were, contrary to earlier historical accounts, also received by Nagumo before the battle began. For reasons which remain unclear, Nagumo did not alter his plans or take additional precautions. | https://en.wikipedia.org/wiki?curid=60112 |
9,689 | Admiral Nimitz had one critical advantage: U.S. cryptanalysts had partially broken the Japanese Navy's JN-25b code. Since early 1942, the U.S. had been decoding messages stating that there would soon be an operation at objective "AF". It was initially not known where "AF" was, but Commander Joseph Rochefort and his team at Station HYPO were able to confirm that it was Midway: Captain Wilfred Holmes devised a ruse of telling the base at Midway (by secure undersea communications cable) to broadcast an uncoded radio message stating that Midway's water purification system had broken down. Within 24 hours, the code breakers picked up a Japanese message that "AF was short on water". No Japanese radio operators who intercepted the message seemed concerned that the Americans were broadcasting uncoded that a major naval installation close to the Japanese threat ring was having a water shortage, which could have tipped off Japanese intelligence officers that it was a deliberate attempt at deception. | https://en.wikipedia.org/wiki?curid=60112 |
9,690 | HYPO was also able to determine the date of the attack as either 4 or 5 June, and to provide Nimitz with a complete IJN order of battle. | https://en.wikipedia.org/wiki?curid=60112 |
9,691 | Japan had a new codebook, but its introduction had been delayed, enabling HYPO to read messages for several crucial days; the new code, which took several days to be cracked, came into use on 24 May, but the important breaks had already been made. | https://en.wikipedia.org/wiki?curid=60112 |
9,692 | As a result, the Americans entered the battle with a good picture of where, when, and in what strength the Japanese would appear. Nimitz knew that the Japanese had negated their numerical advantage by dividing their ships into four separate task groups, so widely separated that they were essentially unable to support each other. This dispersal resulted in few fast ships being available to escort the Carrier Striking Force, thus reducing the number of anti-aircraft guns protecting the carriers. Nimitz calculated that the aircraft on his three carriers, plus those on Midway Island, gave the U.S. rough parity with Yamamoto's four carriers, mainly because American carrier air groups were larger than Japanese ones. The Japanese, by contrast, remained largely unaware of their opponent's true strength and dispositions even after the battle began. | https://en.wikipedia.org/wiki?curid=60112 |
9,693 | At about 09:00 on 3 June, Ensign Jack Reid, piloting a PBY from U.S. Navy patrol squadron VP-44, spotted the Japanese Occupation Force to the west-southwest of Midway. He mistakenly reported this group as the Main Force. | https://en.wikipedia.org/wiki?curid=60112 |
9,694 | Nine B-17s took off from Midway at 12:30 for the first air attack. Three hours later, they found Tanaka's transport group to the west. | https://en.wikipedia.org/wiki?curid=60112 |
9,695 | Harassed by heavy anti-aircraft fire, they dropped their bombs. Although their crews reported hitting four ships, none of the bombs actually hit anything and no significant damage was inflicted. Early the following morning, the Japanese oil tanker "Akebono Maru" sustained the first hit when a torpedo from an attacking PBY struck her around 01:00. This was the only successful air-launched torpedo attack by the U.S. during the entire battle. | https://en.wikipedia.org/wiki?curid=60112 |
9,696 | At 04:30 on 4 June, Nagumo launched his initial attack on Midway itself, consisting of 36 Aichi D3A dive bombers and 36 Nakajima B5N torpedo bombers, escorted by 36 Mitsubishi A6M Zero fighters. At the same time, he launched his seven search aircraft (2 "Kates" from "Akagi" and "Kaga", 4 "Jakes" from "Tone" and "Chikuma", and 1 short range "Dave" from battleship "Haruna"; an eighth aircraft from the heavy cruiser launched 30 minutes late). Japanese reconnaissance arrangements were flimsy, with too few aircraft to adequately cover the assigned search areas, laboring under poor weather conditions to the northeast and east of the task force. As Nagumo's bombers and fighters were taking off, 11 PBYs were leaving Midway to run their search patterns. At 05:34, a PBY reported sighting two Japanese carriers and another spotted the inbound airstrike 10 minutes later. | https://en.wikipedia.org/wiki?curid=60112 |
9,697 | Midway's radar picked up the enemy at a distance of several miles, and interceptors were scrambled. Unescorted bombers headed off to attack the Japanese carriers, their fighter escorts remaining behind to defend Midway. At 06:20, Japanese carrier aircraft bombed and heavily damaged the U.S. base. Midway-based Marine fighters led by Major Floyd B. Parks, which included six F4Fs and 20 F2As, intercepted the Japanese and suffered heavy losses, though they managed to destroy four B5Ns, as well as a single A6M. Within the first few minutes, two F4Fs and 13 F2As were destroyed, while most of the surviving U.S. planes were damaged, with only two remaining airworthy. American anti-aircraft fire was intense and accurate, destroying three additional Japanese aircraft and damaging many more. | https://en.wikipedia.org/wiki?curid=60112 |
9,698 | Of the 108 Japanese aircraft involved in this attack, 11 were destroyed (including three that ditched), 14 were heavily damaged, and 29 were damaged to some degree. The initial Japanese attack did not succeed in neutralizing Midway: American bombers could still use the airbase to refuel and attack the Japanese invasion force, and most of Midway's land-based defenses similarly remained intact. Japanese pilots reported to Nagumo that a second aerial attack on Midway's defenses would be necessary if troops were to go ashore by 7 June. | https://en.wikipedia.org/wiki?curid=60112 |
9,699 | Having taken off prior to the Japanese attack, American bombers based on Midway made several attacks on the Japanese carrier force. These included six Grumman Avengers, detached to Midway from "Hornet"s VT-8 (Midway was the combat debut of both VT-8 and the TBF); Marine Scout-Bombing Squadron 241 (VMSB-241), consisting of 11 SB2U-3s and 16 SBDs, plus four USAAF B-26s of the 18th Reconnaissance and 69th Bomb Squadrons armed with torpedoes, and 15 B-17s of the 31st, 72nd, and 431st Bomb Squadrons. The Japanese repelled these attacks and the attacking force, losing only three Zero fighters while destroying five TBFs, two SB2Us, eight SBDs, and two B-26s. Among the dead was Major Lofton R. Henderson of VMSB-241, killed while leading his inexperienced Dauntless squadron into action. The main airfield at Guadalcanal was named after him in August 1942. | https://en.wikipedia.org/wiki?curid=60112 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.