SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 HC2

2021 HC2

2021 HC2 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.083 AU it takes 1.13 yr to circle the Sun.

Apollo Observations: 22
Orbital Period · P
1.13 yr
v(q)
35 km/s
v(Q)
23.4 km/s
Diameter · ≈
0.01 km
TJ
5.7
Eccentricity · e
0.1978

Orbit and dynamics

Between its closest point (0.869 AU) and its farthest (1.297 AU), the heliocentric distance changes by 0.428 AU over every revolution.

One full revolution takes 1.13 yr (412 days), computed from the semi-major axis of 1.083 AU.

An eccentricity of 0.198 makes the orbit moderately elongated.

Its inclination of 1.51° keeps it close to the plane of the ecliptic.

By the vis-viva equation its orbital speed rises to 35 km/s at perihelion and falls to 23.4 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 = 28.82 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.01 km.

Observation record and orbit quality

Astrometry from 22 individual observations underpins this orbit; the fit leaves an RMS residual of 0.4087 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
1.083 AU
Eccentricity
0.1978
Perihelion
0.869 AU
Aphelion
1.297217 AU
Inclination
1.51°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
265.36°

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
2028-Oct-24 21:54 0.251915 AU
37685949 km
13.51 km/s
2029-Aug-08 21:37 0.274772 AU
41105250 km
5.84 km/s
2030-Apr-18 16:47 0.058177 AU
8703121 km
7.76 km/s
2037-Oct-31 20:39 0.123980 AU
18547209 km
9.77 km/s
2038-Jul-23 15:43 0.282218 AU
42219218 km
5.89 km/s
2039-Apr-26 04:46 0.191587 AU
28661054 km
11.60 km/s
2046-Nov-08 04:33 0.021248 AU
3178721 km
6.22 km/s
2047-Jul-10 11:10 0.268810 AU
40213476 km
5.66 km/s
2048-May-01 02:04 0.300726 AU
44987980 km
14.20 km/s
2055-Nov-04 12:33 0.023047 AU
3447830 km
8.11 km/s
2057-Apr-28 04:44 0.156333 AU
23387083 km
12.19 km/s
2064-Oct-29 17:10 0.097474 AU
14581957 km
11.09 km/s
2066-Apr-23 10:54 0.036160 AU
5409411 km
9.30 km/s
2073-Oct-25 13:55 0.208894 AU
31250082 km
13.86 km/s
2075-Apr-18 11:23 0.001134 AU
169648 km
6.67 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
28.82

Orbit Quality

RMS
0.40867
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.

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