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