| <table border="1"> | |
| <tr><td>Year</td><td>Mass</td><td>Notes</td></tr> | |
| <tr><td>1931</td><td>1 Earth</td><td>Nicholson & Mayall</td></tr> | |
| <tr><td>1942</td><td>0.91 Earth</td><td>Wylie</td></tr> | |
| <tr><td>1948</td><td>0.1 (1/10 Earth)</td><td>Kuiper</td></tr> | |
| <tr><td>1973</td><td>0.025 (1/40 Earth)</td><td>Rawlins</td></tr> | |
| <tr><td>1976</td><td>0.01 (1/100 Earth)</td><td>Cruikshank, Pilcher, & Morrison</td></tr> | |
| <tr><td>1978</td><td>0.002 (1/500 Earth)</td><td>Christy & Harrington</td></tr> | |
| <tr><td>2006</td><td>0.00218 (1/459 Earth)</td><td>Buie et al.</td></tr> | |
| </table> | |