History

JANUARY 12, 1910: A group of diamond miners in the Transvaal in South Africa spot a brilliant comet low in the predawn sky. This was the first sighting of what became known as the “Daylight Comet of 1910” (old style designations 1910a and 1910 I, new style designation C/1910 A1). It soon became one of …

JANUARY 5, 2005: The Kuiper Belt object now known as (136199) Eris is discovered by Mike Brown, Chad Trujillo, and David Rabinowitz on images taken in October 2003. Eris travels around the sun in a moderately-inclined and moderately eccentric orbit with a period of 558 years; it has one known moon (Dysnomia) and turns out …

JANUARY 1, 1801: On the first day of the 19th Century, Giuseppe Piazzi at the Palermo Observatory in Sicily discovers the first-known asteroid, now known as (1) Ceres. As a resident of the “main asteroid belt” between Mars and Jupiter, Ceres remains the largest-known asteroid (diameter 950 km), and is now formally designated a “dwarf …