SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 TH1

2021 TH1

2021 TH1 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.141 AU it takes 1.22 yr to circle the Sun.

Apollo Observations: 10
Orbital Period · P
1.22 yr
v(q)
35.4 km/s
v(Q)
22 km/s
Diameter · ≈
0.01 km
TJ
5.47
Eccentricity · e
0.2342

Orbit and dynamics

The path is an ellipse reaching 0.874 AU from the Sun at perihelion and 1.408 AU at aphelion, a radial span of 0.534 AU.

Applying Kepler's third law to a = 1.141 AU gives an orbital period of 1.22 yr, or about 445 days.

An eccentricity of 0.234 makes the orbit moderately elongated.

Its inclination of 1.43° keeps it close to the plane of the ecliptic.

By the vis-viva equation its orbital speed rises to 35.4 km/s at perihelion and falls to 22 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 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.01 km.

Observation record and orbit quality

The current orbit solution is based on 10 observations and has a weighted RMS residual of 0.5541 arcseconds.

Condition code U = 7 signals a poorly constrained orbit, so its future path should be treated as provisional.

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
1.141 AU
Eccentricity
0.2342
Perihelion
0.874 AU
Aphelion
1.408222 AU
Inclination
1.43°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
356.54°

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
2026-Dec-27 21:08 0.414953 AU
62076027 km
8.15 km/s
2032-Mar-09 13:49 0.265429 AU
39707680 km
5.79 km/s
2037-Apr-04 21:52 0.352157 AU
52681877 km
20.06 km/s
2038-Jan-13 00:58 0.421937 AU
63120829 km
8.31 km/s
2038-Oct-16 10:20 0.297311 AU
44477044 km
18.54 km/s
2049-Oct-07 04:35 0.076578 AU
11455916 km
12.85 km/s
2054-Apr-25 11:56 0.006505 AU
973188 km
8.18 km/s
2054-Dec-10 16:46 0.350379 AU
52415975 km
7.50 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
28.0

Orbit Quality

RMS
0.55407
Condition
7
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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