January 11, 2010 - Make That FOUR Moons

Make That FOUR Moons During the winter of 1609-10, Italian astronomer Galileo Galilei made a series of discoveries that forever changed our understanding of the universe. Using a small telescope that he built, Galileo observed three “stars” that seemed to move in orbits around Jupiter. A week later, he noticed a fourth. These four “Galilean” moons of Jupiter dramatically contradicted the centuries-old notion of an Earth-centered universe by proving that not everything orbits Earth: some things, like these new moons, orbit Jupiter. The first three moons Galileo discovered are called Io, Europa, and Callisto. The fourth, Ganymede, was discovered 400 years ago this week. In this approximately natural color Hubble Space Telescope image from 2007, Ganymede is just about to disappear behind Jupiter.

Image credit: NASA, ESA, and E. Karkoschka (University of Arizona)

Weekly Calendar

January 11-17, 2010

Holidays - Sky Events - Space History

Moon phase Monday 11

Antares 1.1° south of Moon
Venus in superior conjunction

1978: First triple docking: Soyuz 26, Soyuz 27, Salyut 6
1996: STS-72 Endeavour launched
1998: Lunar Prospector arrives at Moon

Moon phase Tuesday 12

1986: STS-61C Columbia launched
1997: STS-81 Atlantis launched
2005: Deep Impact spacecraft launched

Moon phase Wednesday 13

Mercury 5° north of Moon

1610: Galileo discovers Ganymede, moon of Jupiter
1978: NASA selects first women astronauts
1993: STS-54 Endeavour launched

Moon phase Thursday 14

Saturn appears stationary

1975: Earth Resources Technology Satellite is renamed Landsat
2005: Huygens probe lands on Titan
2008: MESSENGER spacecraft makes its first flyby of Mercury

Moon phase Friday 15

New Moon 2:11 AM (eclipse)
Mercury appears stationary

1973: Luna 21 lander and Lunokhod 2 rover land on Moon
1976: Helios 2 launched
2006: Stardust spacecraft returns samples of comet dust

Moon phase Saturday 16

Moon at apogee

1969: First docking of two human spacecraft (Soyuz 5 and Soyuz 4)
2003: STS-107 Columbia launched

Moon phase Sunday 17

Neptune 4° south of Moon

1985: 1,037th and final Aerobee sounding rocket launched

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