March 27, 2017 - Doubling the Asteroids—Twice

Doubling the Asteroids—Twice Two hundred fifteen years ago this week the number of known asteroids doubled—from one to two—when Heinrich Wilhelm Olbers, a physician and astronomer living near Bremen, Germany, discovered Pallas, a rocky body about 512 km (318 mi) in diameter, orbiting between Mars and Jupiter. Five years and one day later, Olbers again doubled the known asteroids, discovering the fourth, dwarf planet Vesta, seen in this image by the Dawn spacecraft. Since then, thousands of asteroids have been cataloged and an estimated 1-2 million asteroids larger than 1 km (0.6 mi) exist in an orbit between Mars and Jupiter. More than a dozen asteroids have been directly imaged by spacecraft, and the two largest (the dwarf planets Vesta and Ceres) were orbited by Dawn.

Image credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

Weekly Calendar

March 27 - April 2, 2017

Holidays - Sky Events - Space History

Monday 27

New Moon 10:57 PM ET

1969: Mariner 7 launched
1972: Venera 8 launched
1989: Contact lost with Phobos 2
1999: First Sea Launch mission
2015: Soyuz TMA-16M launched carrying ISS Expedition 43/44 crew

Tuesday 28

1802: Heinrich Olbers discovers asteroid Pallas
1963: Fourth Saturn C-1 rocket (SA-4) launched
2013: Soyuz TMA-08M launched carrying ISS Expedition 35/36 crew

Wednesday 29

Mercury 7° north of Moon

1807: Heinrich Olbers discovers Vesta
1974: Mariner 10 first Mercury flyby
1989: Starfire 1 launched
2006: ISS Expedition 13 crew launched

Thursday 30

Mars 5° north of Moon
Moon at perigee

2017: SpaceX launches SES-10 satellite, first reflight of orbital-class rocket

Friday 31

1962: NASA approves final design of Gemini spacecraft
1982: Kvant module launched to Mir space station
1997: Pioneer 10 mission officially ends