SpaceAtlas Space Object Data
NASA JPL SBDB · 163818

163818

163818 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.229 AU it takes 1.36 yr to circle the Sun.

Apollo Observations: 971
Orbital Period · P
1.36 yr
v(q)
38.9 km/s
v(Q)
18.5 km/s
Diameter · ≈
0.72 km
TJ
5.13
Eccentricity · e
0.3545

Orbit and dynamics

The path is an ellipse reaching 0.794 AU from the Sun at perihelion and 1.665 AU at aphelion, a radial span of 0.871 AU.

Applying Kepler's third law to a = 1.229 AU gives an orbital period of 1.36 yr, or about 498 days.

An eccentricity of 0.354 makes the orbit moderately elongated.

The orbital plane is tilted 10.39° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 38.9 km/s at perihelion and falls to 18.5 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 0.39 km, a value from direct size determination rather than from brightness alone.

A geometric albedo of 0.516 points to a comparatively bright, reflective surface.

Observation record and orbit quality

The current orbit solution is based on 971 observations and has a weighted RMS residual of 0.5165 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
1.229 AU
Eccentricity
0.3545
Perihelion
0.794 AU
Aphelion
1.664681 AU
Inclination
10.39°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
142.49°

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
2053-Apr-28 19:52 0.172965 AU
25875138 km
14.68 km/s
2068-Apr-27 02:06 0.143123 AU
21410906 km
13.63 km/s

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

Physical Parameters

Diameter
0.386 km
Albedo
0.516
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
18.46

Orbit Quality

RMS
0.51651
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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