SpaceAtlas Space Object Data
NASA JPL SBDB · 2021 FN4

2021 FN4

2021 FN4 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 2.028 AU it takes 2.89 yr to circle the Sun.

Apollo Observations: 176
Orbital Period · P
2.89 yr
v(q)
36.6 km/s
v(Q)
11.9 km/s
Diameter · ≈
0.09 km
TJ
3.64
Eccentricity · e
0.5084

Orbit and dynamics

Between its closest point (0.997 AU) and its farthest (3.059 AU), the heliocentric distance changes by 2.062 AU over every revolution.

One full revolution takes 2.89 yr (1,055 days), computed from the semi-major axis of 2.028 AU.

The high eccentricity (0.508) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 5.66° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 36.6 km/s at perihelion and falls to 11.9 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 = 23.08 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.09 km.

Observation record and orbit quality

Astrometry from 176 individual observations underpins this orbit; the fit leaves an RMS residual of 0.3787 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
2.028 AU
Eccentricity
0.5084
Perihelion
0.997 AU
Aphelion
3.059035 AU
Inclination
5.66°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
265.49°

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
2044-Aug-10 03:22 0.409797 AU
61304745 km
20.67 km/s
2047-May-04 20:45 0.057050 AU
8534619 km
10.64 km/s
2070-Aug-06 02:39 0.341621 AU
51105724 km
18.22 km/s
2073-Apr-27 07:39 0.130193 AU
19476588 km
12.82 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
23.08

Orbit Quality

RMS
0.37871
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.

Keep exploring

Explore asteroids, comets and near-Earth objects with JPL orbital data.