2011 UD21 is an asteroid in the Aten orbit class. Its orbit takes it from 0.95 AU to 1.01 AU from the Sun; one orbit takes 353.6 days. Orbit from the JPL solution of 15 April 2021.
Where is it now
- Distance from Sun
- 0.952 AU
- True anomaly
- 331.78°
- Distance from Earth
- 1.943 AU
- As of
- 24 October 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
- 13h 44m 57s
- Declination
- -10° 52′ 19″
- Constellation
- Virgo
- Distance from Earth
- 1.94 AU
- Elongation from the Sun
- 3.53° — too close to the Sun to observe
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
- 0.979 AU
- Eccentricity
- 0.0304
- Inclination
- 1.06°
- Orbital period
- 353.6 days
- Perihelion
- 0.949 AU
- Aphelion
- 1.008 AU
- Longitude of ascending node
- 22.34°
- Argument of periapsis
- 209.94°
- Epoch · J2000
- 2461200.5
- Orbit class · ATE
- Aten
- Earth MOID · 1.2 LD
- 0.0031 AU
- Tisserand (Jupiter)
- 6.184
Orbit quality
Orbit reasonably well determined (uncertainty code 4).
- Observations used
- 89
- Data arc
- 37 days
- First observed
- 18 October 2011
- Last observed
- 24 November 2011
- Residual RMS
- 0.55 ″
- Solution · Otto Matic
- 15 April 2021
Visual & observation
- Absolute magnitude (H)
- 28.5
Discovery & classification
Listed by JPL impact monitoring; see the Sentry table for current probabilities.
Close approaches 31 on record
Top-down view of the ecliptic, Earth at the centre, for the 2039-10-11 18:28 UTC close approach of 2011 UD21. Catalogue miss distance 182.6 LD · 7.02 × 10⁷ km. The curve is the geocentric path from 2039-10-08 to 2039-10-14, 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 |
|---|---|---|---|---|
| 2039-10-11 18:28:00 | Earth | 0.4691 AU | 182.6 LD | 15.3 km/s |
| 2040-10-04 18:21:00 | Earth | 0.2737 AU | 106.5 LD | 9.4 km/s |
| 2041-09-29 20:49:00 | Earth | 0.0787 AU | 30.6 LD | 3.6 km/s |
| 2042-06-25 16:16:00 | Earth | 0.0606 AU | 23.6 LD | 1.5 km/s |
| 2043-02-02 17:58:00 | Earth | 0.019 AU | 7.4 LD | 1.6 km/s |
| 2044-01-25 05:59:00 | Earth | 0.283 AU | 110.1 LD | 9.8 km/s |
| 2062-10-23 08:06:00 | Earth | 0.4369 AU | 170.0 LD | 14.4 km/s |
| 2063-10-15 06:16:00 | Earth | 0.1672 AU | 65.1 LD | 6.3 km/s |
| 2064-07-16 21:43:00 | Earth | 0.0686 AU | 26.7 LD | 1.5 km/s |
| 2065-01-30 15:43:00 | Earth | 0.0378 AU | 14.7 LD | 2.3 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