SpaceAtlas Space Object Data
NASA JPL SBDB · 1998 WL4

1998 WL4

1998 WL4 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.766 AU it takes 2.35 yr to circle the Sun.

Apollo Observations: 91
Orbital Period · P
2.35 yr
v(q)
57.1 km/s
v(Q)
8.8 km/s
Diameter · ≈
0.45 km
TJ
3.67
Eccentricity · e
0.7329

Orbit and dynamics

The path is an ellipse reaching 0.472 AU from the Sun at perihelion and 3.06 AU at aphelion, a radial span of 2.588 AU.

Applying Kepler's third law to a = 1.766 AU gives an orbital period of 2.35 yr, or about 857 days.

The high eccentricity (0.733) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

A steep inclination of 23.67° carries it well above and below the ecliptic plane.

By the vis-viva equation its orbital speed rises to 57.1 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 = 19.49 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.45 km.

Observation record and orbit quality

The current orbit solution is based on 91 observations and has a weighted RMS residual of 0.71 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
1.766 AU
Eccentricity
0.7329
Perihelion
0.472 AU
Aphelion
3.060301 AU
Inclination
23.67°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
320.63°

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
2031-May-04 23:17 0.464197 AU
69442945 km
26.53 km/s
2059-Oct-01 00:20 0.466606 AU
69803197 km
15.99 km/s
2064-Mar-01 20:41 0.391141 AU
58513838 km
32.13 km/s
2066-Oct-07 06:51 0.240543 AU
35984697 km
22.58 km/s
2071-Mar-21 00:59 0.320329 AU
47920571 km
25.54 km/s
2073-Oct-18 07:40 0.261009 AU
39046444 km
30.55 km/s
2078-Apr-17 13:02 0.404690 AU
60540773 km
24.11 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
19.49

Orbit Quality

RMS
0.70996
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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