SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 AL

2021 AL

2021 AL belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.203 AU it takes 1.32 yr to circle the Sun.

Apollo Observations: 56
Orbital Period · P
1.32 yr
v(q)
37 km/s
v(Q)
20 km/s
Diameter · ≈
0.04 km
TJ
5.24
Eccentricity · e
0.2986

Orbit and dynamics

Between its closest point (0.843 AU) and its farthest (1.562 AU), the heliocentric distance changes by 0.719 AU over every revolution.

One full revolution takes 1.32 yr (482 days), computed from the semi-major axis of 1.203 AU.

An eccentricity of 0.299 makes the orbit moderately elongated.

Its inclination of 1.7° keeps it close to the plane of the ecliptic.

By the vis-viva equation its orbital speed rises to 37 km/s at perihelion and falls to 20 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 = 24.7 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.04 km.

Observation record and orbit quality

Astrometry from 56 individual observations underpins this orbit; the fit leaves an RMS residual of 0.3135 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
1.203 AU
Eccentricity
0.2986
Perihelion
0.843 AU
Aphelion
1.562216 AU
Inclination
1.7°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
346.45°

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
2038-Jul-08 20:15 0.242125 AU
36221396 km
18.80 km/s
2042-Jun-25 05:02 0.012860 AU
1923865 km
11.22 km/s
2054-Jan-18 15:56 0.004827 AU
722163 km
10.19 km/s
2054-Aug-24 18:47 0.435769 AU
65190061 km
8.17 km/s
2058-Jan-03 22:33 0.332517 AU
49743764 km
18.72 km/s
2067-Jul-15 21:12 0.328534 AU
49148003 km
22.72 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
24.7

Orbit Quality

RMS
0.31353
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.