SpaceAtlas Space Object Data
NASA JPL SBDB · 2212

Hephaistos

Hephaistos belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 2.167 AU it takes 3.19 yr to circle the Sun.

Apollo Observations: 5,755
Encyclopedia excerpt
2212 Hephaistos (1978 SB) is an Apollo asteroid and a NEO discovered on 27 September 1978 by L. I. Chernykh at the Crimean Astrophysical Observatory. It is named after the Greek god Hephaestus. It is the largest member of the Hephaistos asteroid group. It makes close approaches to all of the inner planets and will pass 0.048 AU (7.2 million km) from Mercury on September 16, 2032. Other potential members of the Hephaistos group include (85182) 1991 AQ, 4486 Mithra, and D/1766 G1 (Helfenzrieder).
Orbital Period · P
3.19 yr
v(q)
67.4 km/s
v(Q)
6.1 km/s
Diameter · ≈
7.25 km
TJ
3.1
Eccentricity · e
0.8346

Orbit and dynamics

The path is an ellipse reaching 0.358 AU from the Sun at perihelion and 3.976 AU at aphelion, a radial span of 3.618 AU.

Applying Kepler's third law to a = 2.167 AU gives an orbital period of 3.19 yr, or about 1,165 days.

The high eccentricity (0.835) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 11.2° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 67.4 km/s at perihelion and falls to 6.1 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

The measured diameter is 5.7 km, a value from direct size determination rather than from brightness alone.

A geometric albedo of 0.163 points to a comparatively bright, reflective surface.

Observation record and orbit quality

The current orbit solution is based on 5,755 observations and has a weighted RMS residual of 0.4141 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
2.167 AU
Eccentricity
0.8346
Perihelion
0.358 AU
Aphelion
3.975578 AU
Inclination
11.2°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
10.01°

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
5.7 km
Albedo
0.163
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
13.45

Orbit Quality

RMS
0.41411
Condition
0
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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