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March 18, 2013 - Doubling the Size of the Universe

Doubling the Size of the Universe Born 120 years ago this week, German astronomer Walter Baade worked at the Mount Wilson Observatory in California during World War II, taking advantage of the dark skies that resulted from wartime blackouts in Los Angeles. Studying the Andromeda Galaxy and other spiral galaxies, he observed evidence of two different stellar populations, young (Population I) and old (Population II). This led to the discovery that there were actually two different types of the Cepheid variable stars that Edwin Hubble had used to determine the distance to Andromeda. Baade then concluded that the universe was actually twice as large as Edwin Hubble had calculated. In this star field image of Andromeda, the first extragalactic Cepheid variable that Hubble studied is at the lower left.

Image credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Weekly Calendar

March 18-24, 2013

Holidays - Sky Events - Space History

Moon phase Monday 18

Moon at apogee

1965: Voskhod 2 launched, Alexei Leonov takes world’s first spacewalk
1980: Soviet rocket explosion kills 50 workers at Plesetsk launch pad

Moon phase Tuesday 19

First Quarter Moon 1:27 PM ET

1970: First powered flight of X-24A lifting body

Moon phase Wednesday 20

Spring Equinox 7:02 AM ET

Moon phase Thursday 21

1965: Ranger 9 launched

Moon phase Friday 22

1982: STS-3 Columbia launched
1996: STS-76 Atlantis launched
1997: Comet Hale-Bopp closest approach to Earth

Moon phase Saturday 23

1749: Pierre Laplace born
1840
: John William Draper takes first photograph of Moon
1912: Wernher von Braun born
1965: Gemini III launched
2001: Mir space station reenters atmosphere

Moon phase Sunday 24

Palm Sunday

Jupiter 5° north of Aldebaran

1893: Walter Baade born
1992: STS-45 Atlantis launched

Suggestions for new history dates or better links? Corrections for errors on this page? Please e-mail me.