SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 RO9

2021 RO9

2021 RO9 is an Amor-type near-Earth asteroid that approaches Earth from beyond our orbit without crossing it, orbiting the Sun at 2.773 AU once every 4.62 yr.

Amor Observations: 147
Orbital Period · P
4.62 yr
v(q)
34.7 km/s
v(Q)
9.2 km/s
Diameter · ≈
0.57 km
TJ
3.02
Eccentricity · e
0.5799

Orbit and dynamics

Between its closest point (1.165 AU) and its farthest (4.381 AU), the heliocentric distance changes by 3.216 AU over every revolution.

One full revolution takes 4.62 yr (1,687 days), computed from the semi-major axis of 2.773 AU.

The high eccentricity (0.58) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 16.21° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 34.7 km/s at perihelion and falls to 9.2 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 = 18.98 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.57 km.

Observation record and orbit quality

Astrometry from 147 individual observations underpins this orbit; the fit leaves an RMS residual of 0.4466 arcseconds.

Condition code U = 4 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
2.773 AU
Eccentricity
0.5799
Perihelion
1.165 AU
Aphelion
4.381063 AU
Inclination
16.21°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
346.04°

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
2035-Nov-22 17:37 0.476318 AU
71256231 km
12.83 km/s
2072-Dec-10 04:16 0.249834 AU
37374709 km
12.70 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
18.98

Orbit Quality

RMS
0.44663
Condition
4
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.