SpaceAtlas Space Object Data
NASA JPL SBDB · 2017 SK21

2017 SK21

2017 SK21 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.024 AU it takes 1.04 yr to circle the Sun.

Apollo Observations: 20
Orbital Period · P
1.04 yr
v(q)
51.4 km/s
v(Q)
16.8 km/s
Diameter · ≈
0.12 km
TJ
5.7
Eccentricity · e
0.5066

Orbit and dynamics

The path is an ellipse reaching 0.505 AU from the Sun at perihelion and 1.543 AU at aphelion, a radial span of 1.038 AU.

Applying Kepler's third law to a = 1.024 AU gives an orbital period of 1.04 yr, or about 378 days.

The high eccentricity (0.507) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

A steep inclination of 36.71° carries it well above and below the ecliptic plane.

By the vis-viva equation its orbital speed rises to 51.4 km/s at perihelion and falls to 16.8 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 = 22.3 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.12 km.

Observation record and orbit quality

The current orbit solution is based on 20 observations and has a weighted RMS residual of 0.2034 arcseconds.

Condition code U = 9 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
1.024 AU
Eccentricity
0.5066
Perihelion
0.505 AU
Aphelion
1.542758 AU
Inclination
36.71°
Orbital Period
— yr
Epoch
2458022.5
Mean Anomaly
89.84°

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

No close approaches to Earth are currently on record for this object.

Physical Parameters

Diameter
— km
Albedo
—
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
22.3

Orbit Quality

RMS
0.20341
Condition
9
Orbit ID
—
Data source: NASA JPL Small-Body Database . 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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