2017 SP21 is an asteroid in the Aten orbit class. Its orbit takes it from 0.84 AU to 1.12 AU from the Sun; one orbit takes 354.5 days. Orbit from the JPL solution of 15 April 2021.
Where is it now
- Distance from Sun
- 1.087 AU
- True anomaly
- 213.7°
- Distance from Earth
- 1.216 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 43m 29s
- Declination
- -02° 25′ 46″
- Constellation
- Sextans
- Distance from Earth
- 1.21 AU
- Elongation from the Sun
- 57.94° — 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
- 0.98 AU
- Eccentricity
- 0.1388
- Inclination
- 11.21°
- Orbital period
- 354.5 days
- Perihelion
- 0.844 AU
- Aphelion
- 1.116 AU
- Longitude of ascending node
- 188.13°
- Argument of periapsis
- 69.32°
- Epoch · J2000
- 2461200.5
- Orbit class · ATE
- Aten
- Earth MOID · 2.9 LD
- 0.0073 AU
- Tisserand (Jupiter)
- 6.151
Orbit quality
Orbit reasonably well determined (uncertainty code 5).
- Observations used
- 31
- Data arc
- 2 days
- First observed
- 30 September 2017
- Last observed
- 2 October 2017
- Residual RMS
- 0.56 ″
- Solution · Otto Matic
- 15 April 2021
Visual & observation
- Absolute magnitude (H)
- 27.8
Discovery & classification
Close approaches 54 on record
Top-down view of the ecliptic, Earth at the centre, for the 2048-10-13 06:34 UTC close approach of 2017 SP21. Catalogue miss distance 167.4 LD · 6.44 × 10⁷ km. The curve is the geocentric path from 2048-10-10 to 2048-10-16, 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 |
|---|---|---|---|---|
| 2048-10-13 06:34:00 | Earth | 0.4302 AU | 167.4 LD | 18.5 km/s |
| 2049-10-06 23:12:00 | Earth | 0.253 AU | 98.5 LD | 13.5 km/s |
| 2050-10-01 16:13:00 | Earth | 0.0749 AU | 29.2 LD | 8.9 km/s |
| 2051-10-02 14:45:00 | Earth | 0.0975 AU | 37.9 LD | 6 km/s |
| 2052-06-28 04:12:00 | Earth | 0.2463 AU | 95.8 LD | 5.1 km/s |
| 2052-11-25 02:57:00 | Earth | 0.232 AU | 90.3 LD | 5.1 km/s |
| 2053-05-01 07:40:00 | Earth | 0.1941 AU | 75.5 LD | 6.6 km/s |
| 2054-03-23 01:21:00 | Earth | 0.0781 AU | 30.4 LD | 7 km/s |
| 2055-03-05 12:51:00 | Earth | 0.1421 AU | 55.3 LD | 10.1 km/s |
| 2056-02-22 20:04:00 | Earth | 0.3091 AU | 120.3 LD | 14.8 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