SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 UD4

2021 UD4

2021 UD4 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.336 AU it takes 1.54 yr to circle the Sun.

Apollo Observations: 24
Orbital Period · P
1.54 yr
v(q)
35.3 km/s
v(Q)
18.8 km/s
Diameter · ≈
0.02 km
TJ
4.86
Eccentricity · e
0.3045

Orbit and dynamics

The path is an ellipse reaching 0.929 AU from the Sun at perihelion and 1.743 AU at aphelion, a radial span of 0.814 AU.

Applying Kepler's third law to a = 1.336 AU gives an orbital period of 1.54 yr, or about 564 days.

An eccentricity of 0.304 makes the orbit moderately elongated.

The orbital plane is tilted 6.2° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 35.3 km/s at perihelion and falls to 18.8 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 = 26.48 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.02 km.

Observation record and orbit quality

The current orbit solution is based on 24 observations and has a weighted RMS residual of 0.4768 arcseconds.

Condition code U = 8 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
1.336 AU
Eccentricity
0.3045
Perihelion
0.929 AU
Aphelion
1.742812 AU
Inclination
6.2°
Orbital Period
— yr
Epoch
2459513.5
Mean Anomaly
31.44°

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

No close approaches to Earth are currently on record for this object.

Physical Parameters

Diameter
— km
Albedo
—
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
26.48

Orbit Quality

RMS
0.47676
Condition
8
Orbit ID
—
Data source: NASA JPL Small-Body Database . 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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