2021 CS9 is an asteroid in the Aten orbit class. Its orbit takes it from 0.81 AU to 1.16 AU from the Sun; one orbit takes 355.7 days. Orbit from the JPL solution of 15 April 2021.
Where is it now
- Distance from Sun
- 0.865 AU
- True anomaly
- 56.45°
- Distance from Earth
- 0.878 AU
- As of
- 2 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
- 10h 55m 31s
- Declination
- -04° 09′ 20″
- Constellation
- Leo
- Distance from Earth
- 0.88 AU
- Elongation from the Sun
- 54.7° — near the Sun — look low at dusk or dawn
Visible from both hemispheres.
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
- 0.982 AU
- Eccentricity
- 0.1801
- Inclination
- 14.98°
- Orbital period
- 355.7 days
- Perihelion
- 0.806 AU
- Aphelion
- 1.159 AU
- Longitude of ascending node
- 139.25°
- Argument of periapsis
- 258.91°
- Epoch · J2000
- 2461200.5
- Orbit class · ATE
- Aten
- Earth MOID · 0.5 LD
- 0.0014 AU
- Tisserand (Jupiter)
- 6.122
Orbit quality
Orbit poorly determined (uncertainty code 6).
- Observations used
- 41
- Data arc
- 28 days
- First observed
- 7 February 2021
- Last observed
- 7 March 2021
- Residual RMS
- 0.33 ″
- Solution · Otto Matic
- 15 April 2021
Visual & observation
- Absolute magnitude (H)
- 24.29
Discovery & classification
Close approaches 29 on record
Top-down view of the ecliptic, Earth at the centre, for the 2027-07-03 11:13 UTC close approach of 2021 CS9. Catalogue miss distance 163.4 LD · 6.28 × 10⁷ km. The curve is the geocentric path from 2027-06-30 to 2027-07-06, 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. 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 |
|---|---|---|---|---|
| 2027-07-03 11:13:00 | Earth | 0.4198 AU | 163.4 LD | 18.8 km/s |
| 2028-08-05 04:59:00 | Venus | 0.1367 AU | 53.2 LD | 8.9 km/s |
| 2040-04-14 20:19:00 | Venus | 0.1446 AU | 56.3 LD | 9.2 km/s |
| 2055-02-26 18:58:00 | Earth | 0.4616 AU | 179.6 LD | 20.8 km/s |
| 2056-02-20 03:13:00 | Earth | 0.3002 AU | 116.8 LD | 16.3 km/s |
| 2057-02-12 22:12:00 | Earth | 0.1366 AU | 53.2 LD | 12.2 km/s |
| 2058-02-08 01:33:00 | Earth | 0.0263 AU | 10.2 LD | 8.9 km/s |
| 2059-02-12 04:36:00 | Earth | 0.1982 AU | 77.1 LD | 7.8 km/s |
| 2059-10-15 13:19:00 | Earth | 0.2874 AU | 111.8 LD | 7.4 km/s |
| 2060-08-30 04:48:00 | Earth | 0.1908 AU | 74.3 LD | 8.4 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