SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 SP

2021 SP

2021 SP belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.452 AU it takes 1.75 yr to circle the Sun.

Apollo Observations: 12
Orbital Period · P
1.75 yr
v(q)
40.7 km/s
v(Q)
15 km/s
Diameter · ≈
0 km
TJ
4.52
Eccentricity · e
0.4615

Orbit and dynamics

Between its closest point (0.782 AU) and its farthest (2.122 AU), the heliocentric distance changes by 1.34 AU over every revolution.

One full revolution takes 1.75 yr (639 days), computed from the semi-major axis of 1.452 AU.

The high eccentricity (0.462) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

Its inclination of 4.78° keeps it close to the plane of the ecliptic.

By the vis-viva equation its orbital speed rises to 40.7 km/s at perihelion and falls to 15 km/s at aphelion.

Because q < 1 AU and Q > 1 AU, this orbit geometrically intersects the region of Earth's orbit.

Size and surface

No direct size measurement is available; from an absolute magnitude of H = 29.26 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0 km.

Observation record and orbit quality

Astrometry from 12 individual observations underpins this orbit; the fit leaves an RMS residual of 0.9986 arcseconds.

Condition code U = 7 signals a poorly constrained orbit, so its future path should be treated as provisional.

About these computed values

Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

Orbital Parameters

Semi-Major Axis
1.452 AU
Eccentricity
0.4615
Perihelion
0.782 AU
Aphelion
2.122098 AU
Inclination
4.78°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
223.95°

Orbit diagram

The Sun sits at the focus (orange). Earth's orbit is the grey circle at 1 AU. The red dot marks the object's position at the catalog epoch.

3D orbit (interactive)

Drag to rotate; scroll or pinch to zoom. The Sun is at the focus (orange), Earth's orbit is the grey ring at 1 AU, and the red dot marks the object's current position.

Close approaches

Predicted close approaches to Earth, from NASA's Center for Near-Earth Object Studies (CNEOS).

Date (UTC)Miss distanceVelocity
2028-Sep-15 00:56 0.002780 AU
415827 km
13.07 km/s
2035-Sep-07 19:43 0.105778 AU
15824214 km
16.67 km/s
2042-Aug-31 05:36 0.178421 AU
26691425 km
20.62 km/s
2048-Mar-03 00:49 0.276842 AU
41415018 km
24.95 km/s
2049-Aug-24 05:58 0.264353 AU
39546661 km
24.55 km/s
2055-Feb-25 04:59 0.102320 AU
15306850 km
20.93 km/s

Distances in astronomical units (AU) and kilometres. Source: NASA/JPL CNEOS Close Approach Data API.

Physical Parameters

Diameter
— km
Albedo
—
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
29.26

Orbit Quality

RMS
0.99861
Condition
7
Orbit ID
—
Data source: NASA JPL Small-Body Database · NASA CNEOS. Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

Keep exploring

Explore asteroids, comets and near-Earth objects with JPL orbital data.