SpaceAtlas Space Object Data
NASA JPL SBDB · 2018 HK

2018 HK

2018 HK belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.175 AU it takes 1.27 yr to circle the Sun.

Apollo Observations: 64
Orbital Period · P
1.27 yr
v(q)
40.9 km/s
v(Q)
18.4 km/s
Diameter · ≈
0.18 km
TJ
5.2
Eccentricity · e
0.3787

Orbit and dynamics

Between its closest point (0.73 AU) and its farthest (1.62 AU), the heliocentric distance changes by 0.89 AU over every revolution.

One full revolution takes 1.27 yr (465 days), computed from the semi-major axis of 1.175 AU.

An eccentricity of 0.379 makes the orbit moderately elongated.

A steep inclination of 29.36° carries it well above and below the ecliptic plane.

By the vis-viva equation its orbital speed rises to 40.9 km/s at perihelion and falls to 18.4 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 = 21.45 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.18 km.

Observation record and orbit quality

Astrometry from 64 individual observations underpins this orbit; the fit leaves an RMS residual of 0.6782 arcseconds.

Condition code U = 0 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
1.175 AU
Eccentricity
0.3787
Perihelion
0.73 AU
Aphelion
1.619973 AU
Inclination
29.36°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
236.95°

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-Dec-09 14:18 0.438617 AU
65616120 km
17.63 km/s
2032-Apr-09 10:43 0.340452 AU
50930889 km
15.27 km/s
2037-Apr-06 05:44 0.334753 AU
50078264 km
22.22 km/s
2040-Oct-13 23:40 0.160674 AU
24036544 km
19.40 km/s
2045-Dec-27 13:49 0.481659 AU
72055112 km
15.36 km/s
2046-Apr-07 05:09 0.291940 AU
43673614 km
15.51 km/s
2049-Sep-09 15:32 0.485668 AU
72654865 km
28.02 km/s
2051-Apr-09 00:26 0.401560 AU
60072509 km
24.29 km/s
2054-Oct-22 05:35 0.181901 AU
27212062 km
18.71 km/s
2060-Apr-04 15:02 0.250277 AU
37440950 km
16.00 km/s
2063-Sep-15 19:01 0.407321 AU
60934282 km
26.06 km/s
2065-Apr-11 05:50 0.474408 AU
70970451 km
26.49 km/s
2068-Oct-30 15:24 0.232249 AU
34743935 km
18.31 km/s
2074-Apr-03 21:22 0.224034 AU
33515067 km
16.86 km/s
2077-Sep-21 14:55 0.325683 AU
48721473 km
24.07 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
21.45

Orbit Quality

RMS
0.67815
Condition
0
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.