221 Eos

Also known as (221) Eos, Eos

Asteroid In The Asteroid Belt

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: Johann Palisa
Discovery date: 18 January 1882
Pronunciation: / ˈ iː ɒ s /
Named after: Eos
Alternative designations: A882 BA
Minor planet category: Main belt ( Eos )

Article

221 Eos is a large main-belt asteroid that was discovered by Austrian astronomer Johann Palisa on January 18, 1882, in Vienna. In 1884, it was named after Eos, the Greek goddess of the dawn, to honour the opening of a new observatory that was hoped to bring about a new dawn for Viennese astronomy.

The asteroid is orbiting the Sun with a semimajor axis of 3.01 AU, a period of 5.22 years, and an eccentricity of 0.1. The orbital plane is inclined by 10.9° to the plane of the ecliptic. It has a mean cross-section of 104 km, and is spinning with a rotation period of 10.4 hours. Based upon its spectral characteristics, this object is classified as a K-type asteroid. The orbital properties show it to be a member of the extensive Eos asteroid family, which is named after it. The spectral properties of the asteroid suggest it may have come from a partially differentiated parent body.