SpaceAtlas Space Object Data
NASA JPL SBDB · 2018 ER4

2018 ER4

2018 ER4 is an Amor-type near-Earth asteroid that approaches Earth from beyond our orbit without crossing it, orbiting the Sun at 1.903 AU once every 2.63 yr.

Amor Observations: 56
Orbital Period · P
2.63 yr
v(q)
35.7 km/s
v(Q)
13.1 km/s
Diameter · ≈
0.13 km
TJ
3.81
Eccentricity · e
0.4642

Orbit and dynamics

The path is an ellipse reaching 1.02 AU from the Sun at perihelion and 2.786 AU at aphelion, a radial span of 1.766 AU.

Applying Kepler's third law to a = 1.903 AU gives an orbital period of 2.63 yr, or about 959 days.

The high eccentricity (0.464) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

Its inclination of 2.32° keeps it close to the plane of the ecliptic.

By the vis-viva equation its orbital speed rises to 35.7 km/s at perihelion and falls to 13.1 km/s at aphelion.

Its perihelion lies just outside Earth's orbit, which is why it is classed as Earth-approaching rather than Earth-crossing.

Size and surface

No direct size measurement is available; from an absolute magnitude of H = 22.2 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.13 km.

Observation record and orbit quality

The current orbit solution is based on 56 observations and has a weighted RMS residual of 0.3933 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
1.903 AU
Eccentricity
0.4642
Perihelion
1.02 AU
Aphelion
2.786373 AU
Inclination
2.32°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
29.66°

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
2039-May-25 06:34 0.037468 AU
5605122 km
7.23 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
22.2

Orbit Quality

RMS
0.39335
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.

Keep exploring

Explore asteroids, comets and near-Earth objects with JPL orbital data.