IRAS-Araki-Alcock

Orbit and dynamics

The path is an ellipse reaching 0.991 AU from the Sun at perihelion and 195.1 AU at aphelion, a radial span of 194.1 AU.

Applying Kepler's third law to a = 98.03 AU gives an orbital period of 971 yr, or about 354,510 days.

The high eccentricity (0.99) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

A steep inclination of 73.25° carries it well above and below the ecliptic plane.

By the vis-viva equation its orbital speed rises to 42.2 km/s at perihelion and falls to 0.2 km/s at aphelion.

Because q < 1 AU and Q > 1 AU, this orbit geometrically intersects the region of Earth's orbit.

Its Tisserand parameter with respect to Jupiter is T_J = 0.41, a standard discriminator between asteroidal and cometary dynamics.

Size and surface

The measured diameter is 9.2 km, a value from direct size determination rather than from brightness alone.

Its geometric albedo of 0.02 indicates a very dark, carbonaceous-type surface.

Observation record and orbit quality

The current orbit solution is based on 347 observations and has a weighted RMS residual of 0.7737 arcseconds.

Condition code U = 4 indicates a moderately constrained orbit; predictions decades ahead still carry noticeable uncertainty.