2021 AC is an asteroid in the Apollo orbit class. Its orbit takes it from 0.96 AU to 1.11 AU from the Sun; one orbit takes 385.6 days. Orbit from the JPL solution of 7 July 2021.
Where is it now
- Distance from Sun
- 1.084 AU
- True anomaly
- 130.64°
- Distance from Earth
- 1.557 AU
- As of
- 4 November 2026
Two-body Kepler propagation — accurate to ~0.1% for major planets over decades, less so for highly-perturbed bodies. Use JPL Horizons for high precision.
In the sky
- Right ascension
- 17h 42m 07s
- Declination
- -16° 37′ 24″
- Constellation
- Ophiuchus
- Distance from Earth
- 1.56 AU
- Elongation from the Sun
- 43.7° — near the Sun — look low at dusk or dawn
Favours the southern hemisphere; low or below the horizon from far north.
From your location
See how high it is right now, whether it is up after civil twilight, and when it rises and sets where you are.
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Two-body approximation, good to about a degree for the planets — enough to find the constellation and know whether it is up.
Orbital elements
- Semi-major axis
- 1.037 AU
- Eccentricity
- 0.0751
- Inclination
- 26.62°
- Orbital period
- 385.6 days
- Perihelion
- 0.959 AU
- Aphelion
- 1.115 AU
- Longitude of ascending node
- 285.22°
- Argument of periapsis
- 251.42°
- Epoch · J2000
- 2461200.5
- Orbit class · APO
- Apollo
- Earth MOID · 9.0 LD
- 0.023 AU
- Tisserand (Jupiter)
- 5.815
Orbit quality
Orbit very well determined (uncertainty code 2).
- Observations used
- 143
- Data arc
- 183 days
- First observed
- 2 January 2021
- Last observed
- 4 July 2021
- Residual RMS
- 0.58 ″
- Solution · Otto Matic
- 7 July 2021
Visual & observation
- Absolute magnitude (H)
- 23.68
Discovery & classification
Close approaches 99 on record
Top-down view of the ecliptic, Earth at the centre, for the 2038-12-28 17:11 UTC close approach of 2021 AC. Catalogue miss distance 133.8 LD · 5.14 × 10⁷ km. The curve is the geocentric path from 2038-12-25 to 2038-12-31, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is south of the ecliptic. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate.
| When (UTC) | Body | Distance | Lunar distances | Relative speed |
|---|---|---|---|---|
| 2038-12-28 17:11:00 | Earth | 0.3438 AU | 133.8 LD | 18.6 km/s |
| 2039-07-05 06:59:00 | Earth | 0.4471 AU | 174.0 LD | 16.6 km/s |
| 2040-01-06 20:25:00 | Earth | 0.0231 AU | 9.0 LD | 14.1 km/s |
| 2040-07-04 21:44:00 | Earth | 0.1337 AU | 52.0 LD | 13.4 km/s |
| 2041-01-11 16:24:00 | Earth | 0.3374 AU | 131.3 LD | 15.8 km/s |
| 2041-07-10 10:29:00 | Earth | 0.2005 AU | 78.0 LD | 15.5 km/s |
| 2057-12-27 13:06:00 | Earth | 0.3755 AU | 146.1 LD | 19.3 km/s |
| 2058-07-05 08:59:00 | Earth | 0.4792 AU | 186.5 LD | 17.1 km/s |
| 2059-01-05 21:25:00 | Earth | 0.0421 AU | 16.4 LD | 14.3 km/s |
| 2059-07-05 07:38:00 | Earth | 0.1673 AU | 65.1 LD | 13.6 km/s |
Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.
Sources
- visual properties: JPL SBDB (lookup)
- orbital elements: JPL SBDB