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January 17, 2011 - Round And Round They Go

Round and Round They Go The fact that stars appear to be fixed in their positions in the night sky is partly the result of our relatively short life spans. All stars are in motion, most of them imperceptibly, but over time and with increasingly sophisticated observational tools it has become possible to map just where and how fast the stars are moving. Dutch astronomer Jacobus Kapteyn, born 160 years ago this week, devoted considerable effort to measuring the proper motion of stars, and he found that most were not traveling randomly, as had been thought, but were heading in one of two opposing directions. Kapteyn’s analysis provided some of the earliest evidence for the rotation of our galaxy. Seen here is NGC 2903, a rotating barred spiral galaxy slightly smaller than our own, 30 million light-years away.

Image credit: R. Jay GaBany / www.cosmotography.com

Weekly Calendar

January 17-23, 2011

Holidays - Sky Events - Space History

Moon phase Monday 17

Martin Luther King, Jr. Day

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

Moon phase Tuesday 18

2002: Gemini South Observatory dedicated

Moon phase Wednesday 19

Full Moon 4:21 PM ET

1747: Johann Bode born
1851: Jacobus Kapteyn born
1965: Gemini II launched
2006: New Horizons launched

Moon phase Thursday 20

1573: Simon Marius born
1930: Edwin “Buzz” Aldrin born
1966: Apollo A-004 launched, first flight test of CSM hardware
1978: Progress 1 launched

Moon phase Friday 21

Moon at perigee

Moon phase Saturday 22

Juno appears stationary

1968: Apollo 5 launched
1978: First automatic resupply ship docking (Progress 1)
1992: STS-42 Discovery launched
1998: STS-89 Endeavour launched
2003: Pioneer 10’s last signal to Earth

Moon phase Sunday 23

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