SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 PD9

2021 PD9

2021 PD9 is an Amor-type near-Earth asteroid that approaches Earth from beyond our orbit without crossing it, orbiting the Sun at 2.357 AU once every 3.62 yr.

Amor Observations: 152
Orbital Period · P
3.62 yr
v(q)
33.2 km/s
v(Q)
11.3 km/s
Diameter · ≈
0.13 km
TJ
3.38
Eccentricity · e
0.4906

Orbit and dynamics

The path is an ellipse reaching 1.201 AU from the Sun at perihelion and 3.513 AU at aphelion, a radial span of 2.312 AU.

Applying Kepler's third law to a = 2.357 AU gives an orbital period of 3.62 yr, or about 1,322 days.

The high eccentricity (0.491) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

Its inclination of 1.87° keeps it close to the plane of the ecliptic.

By the vis-viva equation its orbital speed rises to 33.2 km/s at perihelion and falls to 11.3 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 = 22.15 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 152 observations and has a weighted RMS residual of 0.4048 arcseconds.

Condition code U = 5 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
2.357 AU
Eccentricity
0.4906
Perihelion
1.201 AU
Aphelion
3.513344 AU
Inclination
1.87°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
102.72°

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
2050-Oct-15 03:04 0.230446 AU
34474168 km
3.59 km/s
2079-Oct-20 18:54 0.300303 AU
44924620 km
4.48 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
22.15

Orbit Quality

RMS
0.40477
Condition
5
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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