SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 AD4

2021 AD4

2021 AD4 is an Aten-type near-Earth asteroid whose orbit lies mostly inside that of Earth, with a semi-major axis of 0.907 AU and a period of 0.86 yr.

Aten Observations: 42
Orbital Period · P
0.86 yr
v(q)
34.2 km/s
v(Q)
28.6 km/s
Diameter · ≈
0.03 km
TJ
6.56
Eccentricity · e
0.0881

Orbit and dynamics

The path is an ellipse reaching 0.827 AU from the Sun at perihelion and 0.987 AU at aphelion, a radial span of 0.16 AU.

Applying Kepler's third law to a = 0.907 AU gives an orbital period of 0.86 yr, or about 316 days.

With e = 0.088, the orbit is close to circular.

The orbital plane is tilted 9.46° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 34.2 km/s at perihelion and falls to 28.6 km/s at aphelion.

Size and surface

No direct size measurement is available; from an absolute magnitude of H = 25.66 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.03 km.

Observation record and orbit quality

The current orbit solution is based on 42 observations and has a weighted RMS residual of 0.4499 arcseconds.

Condition code U = 6 indicates a moderately constrained orbit; predictions decades ahead still carry noticeable uncertainty.

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
0.9072 AU
Eccentricity
0.0881
Perihelion
0.827 AU
Aphelion
0.987124 AU
Inclination
9.46°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
262.05°

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
2026-Dec-31 03:35 0.259009 AU
38747210 km
10.95 km/s
2027-Jun-24 03:09 0.184385 AU
27583624 km
6.88 km/s
2033-Aug-26 04:58 0.204665 AU
30617412 km
6.01 km/s
2034-Jan-27 06:03 0.204535 AU
30598013 km
8.78 km/s
2040-Jan-03 04:42 0.048690 AU
7283887 km
5.91 km/s
2046-Jan-02 14:53 0.412188 AU
61662465 km
15.59 km/s
2046-Jul-24 14:12 0.190300 AU
28468465 km
7.00 km/s
2047-Jan-31 12:53 0.363616 AU
54396144 km
13.24 km/s
2053-Jan-10 03:13 0.032287 AU
4830074 km
5.17 km/s
2058-Dec-30 20:09 0.209269 AU
31306154 km
9.59 km/s
2059-Jun-14 06:31 0.184788 AU
27643944 km
6.65 km/s
2065-Aug-08 21:08 0.199332 AU
29819573 km
6.74 km/s
2066-Jan-30 19:04 0.288530 AU
43163423 km
11.08 km/s
2072-Jan-10 04:14 0.016074 AU
2404666 km
5.15 km/s
2077-Dec-30 15:53 0.118682 AU
17754599 km
7.68 km/s
2078-May-28 04:34 0.187000 AU
27974753 km
6.06 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
25.66

Orbit Quality

RMS
0.44989
Condition
6
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.

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