138971
Add to an observing list or journal →138971 (2001 CB21)
138971 is an asteroid in the Apollo orbit class. Its orbit takes it from 0.69 AU to 1.38 AU from the Sun; one orbit takes 383.8 days. Discovered 2 February 2001 by LINEAR. Orbit from the JPL solution of 2 November 2026.
Where is it now
- Distance from Sun
- 1.173 AU
- True anomaly
- 130.64°
- Distance from Earth
- 0.231 AU
- As of
- 3 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
- 23h 43m 43s
- Declination
- +28° 53′ 25″
- Constellation
- Pegasus
- Distance from Earth
- 0.24 AU
- Elongation from the Sun
- 137.51° — well clear of the Sun
Favours the northern hemisphere; low or below the horizon from far south.
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.
Your location stays in your browser and is sent only for this calculation. Using a what3words address is optional; if you do, the three words go to what3words to be converted and we don't record them. Set a location first, then you can save an email alert for this object. See our privacy policy.
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
- 1.034 AU
- Eccentricity
- 0.3333
- Inclination
- 7.92°
- Orbital period
- 383.8 days
- Perihelion
- 0.689 AU
- Aphelion
- 1.378 AU
- Longitude of ascending node
- 353.64°
- Argument of periapsis
- 271.95°
- Epoch · J2000
- 2461200.5
- Orbit class · APO
- Apollo
- Earth MOID · 9.2 LD
- 0.0237 AU
- Tisserand (Jupiter)
- 5.867
Orbit quality
Orbit very well determined (uncertainty code 0).
- Observations used
- 2,943
- Data arc
- 25.74 years
- First observed
- 2 February 2001
- Last observed
- 1 November 2026
- Residual RMS
- 0.33 ″
- Solution · Otto Matic
- 2 November 2026
Physical properties
- Rotation period
- 3.3 hours
Visual & observation
- Absolute magnitude (H)
- 18.54
Discovery & classification
- Discovered by
- LINEAR
- Discovery date
- 2 February 2001
- Discovery site
- Socorro
Also known as 2001 CB21
Close approaches 64 on record
Top-down view of the ecliptic, Earth at the centre, for the 2043-03-06 09:23 UTC close approach of 138971. Catalogue miss distance 12.5 LD · 4.82 × 10⁶ km. The curve is the geocentric path from 2043-03-03 to 2043-03-09, 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 north 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 |
|---|---|---|---|---|
| 2037-02-11 06:23:00 | Venus | 0.0671 AU | 26.1 LD | 7.6 km/s |
| 2043-03-06 09:23:00 | Earth | 0.0322 AU | 12.5 LD | 10.8 km/s |
| 2044-05-04 06:54:00 | Venus | 0.1422 AU | 55.3 LD | 13.3 km/s |
| 2047-10-01 07:19:00 | Earth | 0.036 AU | 14.0 LD | 11.3 km/s |
| 2054-12-28 14:47:00 | Venus | 0.0842 AU | 32.8 LD | 12.9 km/s |
| 2062-04-24 07:55:00 | Venus | 0.0885 AU | 34.4 LD | 7.2 km/s |
| 2063-02-26 05:24:00 | Earth | 0.1736 AU | 67.6 LD | 16.4 km/s |
| 2064-03-11 00:21:00 | Earth | 0.1489 AU | 57.9 LD | 7.4 km/s |
| 2067-09-17 17:13:00 | Earth | 0.1839 AU | 71.6 LD | 6.8 km/s |
| 2068-10-06 20:31:00 | Earth | 0.1411 AU | 54.9 LD | 15.3 km/s |
Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.
Sources
- visual properties: JPL SBDB (lookup)
- physical properties: JPL SBDB (lookup)
- orbital elements: JPL SBDB