| Discovery[1] | |
|---|---|
| Discovered by | T. Urata |
| Discovery site | Yakiimo Stn. |
| Discovery date | 12 March 1978 |
| Designations | |
| (2090) Mizuho | |
Named after | Mizuho Urata (daughter of discoverer)[2] |
| 1978 EA · 1937 RE 1942 PG · 1951 EH 1952 HA4 · 1953 RT 1953 TP · 1959 VD 1964 TE · 1970 WV 1978 EJ | |
| main-belt · (outer)[3] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 66.14 yr (24,157 days) |
| Aphelion | 3.4819AU |
| Perihelion | 2.6635 AU |
| 3.0727 AU | |
| Eccentricity | 0.1332 |
| 5.39yr (1,967 days) | |
| 337.47° | |
| 0° 10m 58.8s / day | |
| Inclination | 11.814° |
| 339.85° | |
| 341.20° | |
| Physical characteristics | |
| Dimensions | 17.991±0.141[4] 18.185±0.117 km[5] 18.92±0.79 km[6] 35.28 km(calculated)[3] |
| 5.47±0.01h[7] | |
| 0.057(assumed)[3] 0.207±0.019[6] 0.2154±0.0435[5] 0.219±0.029[4] | |
| Tholen =S[1] · S[3] B–V = 0.871[1] U–B = 0.499[1] | |
| 10.99[1][3][5][6] | |
2090 Mizuho, provisional designation1978 EA, is a stonyasteroid from the outer region of theasteroid belt, approximately 18 kilometers in diameter.
The asteroid was discovered on 12 March 1978, by Japanese astronomerTakeshi Urata at theJCPM Yakiimo Station in Shimizu, Japan, who named it after his daughter, Mizuho Urata.[8]
Mizuho orbits the Sun in theouter main-belt at a distance of 2.7–3.5 AU once every 5 years and 5 months (1,967 days). Its orbit has aneccentricity of 0.13 and aninclination of 12° with respect to theecliptic.[1]
The asteroid was first identified as1937 RE atSimeiz Observatory. The first used observation was obtained atHeidelberg Observatory in 1951, extending theMizuho'sobservation arc by 27 years prior to its official discovery observation.[8]
In theTholen classification,Mizuho is characterized as a commonS-type asteroid.[1]
In February 2010, a rotationallightcurve forMizuho was obtained from photometric observations by James W. Brinsfield at the Via Capote Observatory (G69) in California. It gave arotation period of 5.47 hours with a brightness variation of 0.30magnitude (U=2+).[7]
According to the surveys carried out by the JapaneseAkari satellite, and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Mizuho measures between 18.0 and 18.9 kilometers in diameter and its surface has analbedo of between 0.207 and 0.219, which is typical for stony asteroids.[4][5][6] TheCollaborative Asteroid Lightcurve Link, however assumes a standard albedo for a carbonaceousC-type asteroid of 0.057 and correspondingly calculates a much larger diameter of 35.3 kilometers.[3]
The discoverer named thisminor planet after his daughter, Mizuho Urata.[2] It was the first asteroid in over 50 years to be discovered by a non-professional astronomer, which set off a wave of interest in amateur asteroid discovery, especially in Japan.[9] The officialnaming citation was published by theMinor Planet Center on 1 September 1978 (M.P.C. 4482).[10]
