SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 WD

2021 WD

2021 WD belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 2.396 AU it takes 3.71 yr to circle the Sun.

Apollo Observations: 65
Orbital Period · P
3.71 yr
v(q)
42.3 km/s
v(Q)
8.8 km/s
Diameter · ≈
0.2 km
TJ
3.18
Eccentricity · e
0.6568

Orbit and dynamics

The path is an ellipse reaching 0.823 AU from the Sun at perihelion and 3.97 AU at aphelion, a radial span of 3.147 AU.

Applying Kepler's third law to a = 2.396 AU gives an orbital period of 3.71 yr, or about 1,355 days.

The high eccentricity (0.657) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 9.1° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 42.3 km/s at perihelion and falls to 8.8 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 = 21.3 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.2 km.

Observation record and orbit quality

The current orbit solution is based on 65 observations and has a weighted RMS residual of 0.3593 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
2.396 AU
Eccentricity
0.6568
Perihelion
0.823 AU
Aphelion
3.969693 AU
Inclination
9.1°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
93.49°

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
2069-Dec-11 07:14 0.377922 AU
56536255 km
26.58 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
21.3

Orbit Quality

RMS
0.3593
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.

Keep exploring

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