57 Mnemosyne

Also known as (57) Mnemosyne, Mnemosyne

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: Karl Theodor Robert Luther
Discovery date: 22 September 1859
Pronunciation: / n ɪ ˈ m ɒ s ɪ n iː /
Named after: Mnemosyne
Minor planet category: Main belt
Adjectives: Mnemosynean / ˌ n ɛ m ə s ɪ ˈ n iː ə n / , Mnemosynian / n ɛ m ə ˈ s ɪ n i ə n /

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Article

57 Mnemosyne is a large main belt asteroid. It is a stony S-type asteroid in composition. This object was discovered by Robert Luther on 22 September 1859 in Düsseldorf. Its name was chosen by Martin Hoek, the director of the Utrecht Observatory, in reference to Mnemosyne, a Titaness in Greek mythology.

This asteroid is orbiting in the outer main belt at a distance of 3.149 AU from the Sun with an eccentricity (ovalness) of 0.118 and a period of 5.58811 a. The orbital plane is inclined at an angle of 15.2° to the ecliptic. The orbital period of this asteroid is close to a 2:1 commensurability with Jupiter, which made it useful for perturbation measurements to derive the mass of the planet.