SpaceAtlas Space Object Data
NASA JPL SBDB · 2001 WJ4

2001 WJ4

2001 WJ4 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.256 AU it takes 1.41 yr to circle the Sun.

Apollo Observations: 28
Orbital Period · P
1.41 yr
v(q)
33.1 km/s
v(Q)
21.3 km/s
Diameter · ≈
0.01 km
TJ
5.09
Eccentricity · e
0.2165

Orbit and dynamics

Between its closest point (0.984 AU) and its farthest (1.528 AU), the heliocentric distance changes by 0.544 AU over every revolution.

One full revolution takes 1.41 yr (514 days), computed from the semi-major axis of 1.256 AU.

An eccentricity of 0.216 makes the orbit moderately elongated.

The orbital plane is tilted 7.9° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 33.1 km/s at perihelion and falls to 21.3 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 = 27.4 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.01 km.

Observation record and orbit quality

Astrometry from 28 individual observations underpins this orbit; the fit leaves an RMS residual of 0.5271 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
1.256 AU
Eccentricity
0.2165
Perihelion
0.984 AU
Aphelion
1.527924 AU
Inclination
7.9°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
149.74°

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
2029-Jul-02 21:01 0.486558 AU
72787996 km
7.96 km/s
2032-Oct-19 16:46 0.200552 AU
30002157 km
11.73 km/s
2033-Mar-18 14:21 0.305774 AU
45743164 km
5.11 km/s
2057-May-11 12:49 0.473895 AU
70893631 km
8.43 km/s
2061-Feb-01 03:12 0.339724 AU
50821980 km
17.05 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
27.4

Orbit Quality

RMS
0.52707
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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