SpaceAtlas Space Object Data
NASA JPL SBDB · 2008 US4

2008 US4

2008 US4 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 2.336 AU it takes 3.57 yr to circle the Sun.

Apollo Observations: 231
Orbital Period · P
3.57 yr
v(q)
41.1 km/s
v(Q)
9.2 km/s
Diameter · ≈
0.23 km
TJ
3.24
Eccentricity · e
0.6326

Orbit and dynamics

The path is an ellipse reaching 0.858 AU from the Sun at perihelion and 3.814 AU at aphelion, a radial span of 2.956 AU.

Applying Kepler's third law to a = 2.336 AU gives an orbital period of 3.57 yr, or about 1,304 days.

The high eccentricity (0.633) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 13.18° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 41.1 km/s at perihelion and falls to 9.2 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

The measured diameter is 0.52 km, a value from direct size determination rather than from brightness alone.

Its geometric albedo of 0.029 indicates a very dark, carbonaceous-type surface.

Observation record and orbit quality

The current orbit solution is based on 231 observations and has a weighted RMS residual of 0.3736 arcseconds.

Condition code U = 0 means the orbit is very well determined, leaving only a small uncertainty in the future ephemeris.

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
2.336 AU
Eccentricity
0.6326
Perihelion
0.858 AU
Aphelion
3.813754 AU
Inclination
13.18°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
322.98°

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
2033-Nov-06 06:03 0.113396 AU
16963792 km
16.97 km/s
2041-Mar-18 16:03 0.320003 AU
47871774 km
22.00 km/s
2058-Oct-21 17:29 0.366649 AU
54849874 km
24.93 km/s
2066-Feb-28 17:37 0.180988 AU
27075348 km
13.46 km/s

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

Physical Parameters

Diameter
0.516 km
Albedo
0.029
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
20.96

Orbit Quality

RMS
0.37362
Condition
0
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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