SpaceAtlas Space Object Data
NASA JPL SBDB · 2018 AJ

2018 AJ

2018 AJ belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.421 AU it takes 1.69 yr to circle the Sun.

Apollo Observations: 106
Orbital Period · P
1.69 yr
v(q)
34.3 km/s
v(Q)
18.2 km/s
Diameter · ≈
0.04 km
TJ
4.65
Eccentricity · e
0.3064

Orbit and dynamics

The path is an ellipse reaching 0.985 AU from the Sun at perihelion and 1.856 AU at aphelion, a radial span of 0.871 AU.

Applying Kepler's third law to a = 1.421 AU gives an orbital period of 1.69 yr, or about 619 days.

An eccentricity of 0.306 makes the orbit moderately elongated.

The orbital plane is tilted 5.67° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 34.3 km/s at perihelion and falls to 18.2 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

No direct size measurement is available; from an absolute magnitude of H = 24.54 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.04 km.

Observation record and orbit quality

The current orbit solution is based on 106 observations and has a weighted RMS residual of 0.3962 arcseconds.

Condition code U = 2 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
1.421 AU
Eccentricity
0.3064
Perihelion
0.985 AU
Aphelion
1.856394 AU
Inclination
5.67°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
332.22°

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
2034-Dec-16 14:56 0.401938 AU
60129060 km
16.91 km/s
2035-May-19 01:19 0.470592 AU
70399522 km
5.76 km/s
2040-Feb-24 22:32 0.062514 AU
9351959 km
5.56 km/s
2057-Jan-05 22:11 0.108135 AU
16176781 km
8.18 km/s
2061-Nov-14 10:38 0.434220 AU
64958395 km
4.91 km/s
2062-Apr-05 03:16 0.337080 AU
50426383 km
14.46 km/s
2073-Dec-15 00:07 0.430658 AU
64425520 km
17.79 km/s
2074-May-21 22:26 0.485668 AU
72654858 km
6.10 km/s
2079-Feb-23 12:08 0.059947 AU
8967899 km
5.47 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
24.54

Orbit Quality

RMS
0.39617
Condition
2
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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