(21561) Masterman Main-belt Asteroid
Discovered on 28 August 1998 by LINEAR at Socorro.
Mary Masterman (b. 1989) was awarded first place in the 2006 Intel International Science and Engineering Fair for her physics project. She attends the Westmoore High School, Oklahoma City, Oklahoma, U.S.A.Naming citation (20060711/MPCPages.arc), IAU / Minor Planet Center, via NASA/JPL
Where Masterman is today
Seen from above the solar system on 2026-10-14: Masterman is 3.05 au from the Sun and 4.00 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 21561 |
| Provisional designation | 1998 QR93 |
| Orbit class | Main-belt Asteroid |
| Diameter | 7.07 km (#7,564 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.245 |
| Rotation period | 172 hours |
| Absolute magnitude (H) | 13.14 |
| Orbital period | 4.39 years |
| Semi-major axis | 2.68 au |
| Perihelion – aphelion | 2.24 – 3.13 au |
| Eccentricity | 0.166 |
| Inclination | 13.9° |
| Closest distance between its orbit and Earth's (MOID) | 1.25 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.
Also named after someone called Mary
- (4793) Slessor
- (5595) Roth
- (6603) Marycragg
- (7091) Maryfields
- (7958) Leakey
- (9824) Marylea
- (10870) Gwendolen
- (11369) Brazelton
- (12590) Ballantine
- (12627) Maryedwards
- (12628) Acworthorr
- (13412) Guerrieri
All asteroids named after someone called Mary
Also discovered on 28 August 1998
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- (13292) Hernandezmon
- (14124) Kamil
- (14575) Jamesblanc
- (14576) Jefholley
- (16962) Elizawoolard
- (17870) Pannett
- (20413) Josephdemartini
- (21560) Analyons
- (23833) Mowers
- (23834) Mukhopadhyay
- (25075) Kiyomoto