42 Isis

Also known as (42) Isis, Isis

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: Norman Robert Pogson
Discovery date: 23 May 1856
Pronunciation: / ˈ aɪ s ɪ s /
Named after: Isis Pogson
Minor planet category: Main belt
Adjectives: Isidian / aɪ ˈ s ɪ d i ə n /
Aphelion: 446.706 million km (2.986 AU )
Perihelion: 283.890 million km (1.898 AU)
Semi major axis: 365.298 million km (2.442 AU)
Orbital period sidereal: 1393.737 d (3.82 a )
Mean anomaly: 121.874°
Inclination: 8.530°
Longitude of ascending node: 84.398°
Time of perihelion: 2024-Oct-17
Argument of perihelion: 236.626°
Dimensions: 102.73 ± 2.73 km
Mass: (1.58 ± 0.52) × 10 kg
Mean density: 2.78 ± 0.93 g/cm

via Wikipedia infobox

Wikidata facts

Diameter: 110.997
Orbital period: 1395.387498973379
Image: 42Isis (Lightcurve Inversion).png

Show 15 more facts

provisional designation: A856 KB
time of discovery or invention: 1856-05-23
albedo: 0.139
Commons category: 42 Isis
rotation period: 13.59
absolute magnitude: 7.7
orbital eccentricity: 0.2219265527462281
semi-major axis of an orbit: 2.443792160841234
periapsis: 1.901449790957483
apoapsis: 2.986134530724984
orbital inclination: 8.510020395102432
longitude of ascending node: 84.16706268549844
argument of periapsis: 237.4114666325958
mean anomaly: 103.0390207766048
time of periapsis: 2460601.1128847273

Sources (2)

via Wikidata · CC0

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Article

42 Isis is a large main-belt asteroid, measuring 100.2 km in diameter with a stony (S-type) composition. It was discovered by English astronomer N.R. Pogson on 23 May 1856 at Oxford, and was his first asteroid discovery. The asteroid's name was chosen by Manuel John Johnson, director of the Radcliffe Observatory in Oxford. Although Isis is the name of an Egyptian goddess, the name was chosen in homage to Pogson's astronomer daughter, (Elizabeth) Isis Pogson. In addition, the Isis is the stretch of the River Thames that runs through Oxford.

This asteroid is orbiting the Sun with a period of 3.82 years. The light curve inversion technique, when applied to photometric observations of this asteroid, show multiple local irregularities. The overall shape displays little elongation, with a ratio between the major and minor axes equal to 1.1. The measured rotation period for this model is 13.6 hours. The spectrum of 42 Isis reveals the strong presence of the mineral olivine, a relative rarity in the asteroid belt.