42 Isis

Also known as (42) Isis, Isis

main-belt asteroid

Picture of the Day · NASA

Jupiter and Venus from Earth

2026-06-07

It was visible around the world. The sunset conjunction of Jupiter (left) and Venus (right) in 2012 was visible almost no matter where you lived on Earth. Anyone on our planet with a clear western horizon at sunset could see them. That year, a creative photographer traveled away from the town lights of Szubin, Poland to photograph a near closest approach of the two planets. The bright planets were then separated by only three degrees and his daughter struck a humorous pose. A faint red sunset still glowed in the background. Jupiter and Venus are together again this week after sunset, passing within a degree of each other about two days from today.

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 /

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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.