99 Dike

Also known as (99) Dike, Dike

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: Alphonse Borrelly
Discovery date: 28 May 1868
Pronunciation: / ˈ d aɪ k iː /
Named after: Dike
Alternative designations: A915 BA; 1935 UC; 1935 YL; 1939 UT; 1948 UE; 1948 WC; 1961 XJ; 1974 VB
Minor planet category: Main belt

Article

99 Dike (/ˈdaɪkiː/) is a quite large and dark main-belt asteroid. Dike was discovered by Alphonse Borrelly on May 28, 1868. It was his first asteroid discovery. This object is named after Dike, the Greek goddess of moral justice. Among the first hundred numbered minor planets, 99 Dike was considered anomalously faint for over a century. However, this was later found to be untrue.

This asteroid is orbiting the Sun with a period of 4.35 years and an eccentricity of 0.19. Its orbital plane is inclined by 13.8° to the plane of the ecliptic. The body spans a diameter of 69 km and it is classified as a C-type asteroid, which indicates it has a dark, carbonaceous surface. Based upon a light curve that was generated from photometric observations of this asteroid at Pulkovo Observatory, it has a rotation period of 18.127 ± 0.002 hours and varies in brightness by 0.22 ± 0.02 in magnitude. However, according to Shrindan E. (2009) the rotation period is rather of 10.360 ± 0.001 h.