SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 PC9

2021 PC9

2021 PC9 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.847 AU it takes 2.51 yr to circle the Sun.

Apollo Observations: 61
Orbital Period · P
2.51 yr
v(q)
49 km/s
v(Q)
9.8 km/s
Diameter · ≈
0.2 km
TJ
3.69
Eccentricity · e
0.6672

Orbit and dynamics

Between its closest point (0.615 AU) and its farthest (3.079 AU), the heliocentric distance changes by 2.464 AU over every revolution.

One full revolution takes 2.51 yr (917 days), computed from the semi-major axis of 1.847 AU.

The high eccentricity (0.667) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 11.3° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 49 km/s at perihelion and falls to 9.8 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 = 21.2 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.2 km.

Observation record and orbit quality

Astrometry from 61 individual observations underpins this orbit; the fit leaves an RMS residual of 0.5517 arcseconds.

Condition code U = 1 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
1.847 AU
Eccentricity
0.6672
Perihelion
0.615 AU
Aphelion
3.079318 AU
Inclination
11.3°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
2.93°

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
2031-Jul-27 17:22 0.139924 AU
20932378 km
16.84 km/s
2036-Aug-03 23:01 0.024386 AU
3648088 km
20.14 km/s
2041-Aug-06 16:28 0.021336 AU
3191757 km
21.37 km/s
2046-Aug-12 22:17 0.134236 AU
20081386 km
24.59 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
21.2

Orbit Quality

RMS
0.55172
Condition
1
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

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