81 Terpsichore

Also known as (81) Terpsichore, Terpsichore

main-belt asteroid

Picture of the Day · NASA

Pathfinder on Mars

2026-07-04

On July 4th, 1997, using its own array of fireworks, a parachute, and a cocoon of airbags, the Mars Pathfinder spacecraft bounced like a giant beach ball at least 15 times before it came to rest on the surface of Mars at 10:07 AM Pacific Daylight Time. After its then novel airbag-assisted landing sequence was completed, Pathfinder transmitted this color mosaic to mission operators on Earth. In the scene from another world, the Mars Sojourner robot rover is visible in the foreground, crouched on top of the unfolded Pathfinder. About the size of a large house cat, the six-wheeled, solar-powered Sojourner became the first successful Martian rover. Surrounding Pathfinder are deflated airbags and the rock-strewn terrain of the Ares Vallis floodplain. In the distance Martian hills appear against a dusty brownish sky. The Pathfinder lander was subsequently renamed the Carl Sagan Memorial Station.

via NASA APOD

Key facts

Discovered by: Ernst Wilhelm Tempel
Discovery date: September 30, 1864
Pronunciation: / t ɜːr p ˈ s ɪ x ər ɛ /
Named after: Terpsichore
Minor planet category: Main belt
Adjectives: Terpsichorean / t ɜːr p s ɪ x ə ˈ r iː ə n /
Aphelion: 516.955 million km (3.456 AU)
Perihelion: 337.132 million km (2.254 AU)
Semi major axis: 427.044 million km (2.855 AU )
Orbital period sidereal: 1761.647 d (4.82 a )
Average orbital speed: 17.43 km/s
Mean anomaly: 149.581°
Inclination: 7.809°
Longitude of ascending node: 1.497°
Argument of perihelion: 50.234°
Dimensions: 121.77 ± 2.34 km
Mass: (6.19 ± 5.31) × 10 kg
Mean density: 6.54 ± 5.62 g/cm

via Wikipedia infobox

~2 min read

Encyclopedic overview

81 Terpsichore is a large and very dark main-belt asteroid. It has most probably a very primitive carbonaceous composition. It was found by the prolific comet discoverer Ernst Tempel on September 30, 1864. It is named after Terpsichore, the Muse of dance in Greek mythology.

This object is orbiting the Sun at a distance of 2.855 AU with a moderate eccentricity of 0.212 and an orbital period of 4.82 years. The orbital plane is inclined at an angle of 7.80° relative to the plane of the ecliptic. Infrared measurements provide a diameter estimate of 117.7±0.7 km. It has the spectrum of a carbonaceous C-type asteroid.

Excerpted from Wikipedia’s “81 Terpsichore” article, available under the CC BY-SA 4.0 licence.