April 20, 2009 - Three of a Kind
Three of a Kind Although the nebulae in deep space do resemble clouds, their composition is quite different from their terrestrial namesakes, which are composed primarily of condensed water vapor. This image by amateur astronomer R. Jay GaBany depicts three different types of nebulae that lie about five thousand light-years away in the constellation Sagittarius. Barnard 91 is the prominent dark nebula, a molecular cloud (usually composed primarily of hydrogen) that contains enough dust grains to become opaque. IC 1274 is the blue reflection nebula, a cloud of gas and dust that simply reflects or scatters the light of nearby stars. The red regions are emission nebulae, clouds of ionized gas emitting light of various colors (as neon lights do), usually activated by radiation emitted from a nearby hot star.
Image Credit: R. Jay GaBany / www.cosmotography.com
Weekly Calendar
April 20-26, 2009
Holidays - Sky Events - Space History
Monday 20
1972: Apollo 16 lands on Moon
Tuesday 21
Lyrid meteor shower
1997: Cremated remains of 24 people launched into orbit aboard Pegasus rocket in first space funeral
Wednesday 22
Uranus 5° S of Moon
Venus 1.1° S of Moon
Lyrid meteor shower
Thursday 23
1858: Max Planck born
1962: Ranger 4 launched
1963: M2-F1 lifting body first free flight
1996: Priroda module launched to Mir space station
Friday 24
New Moon 11:23 pm
1970: China becomes fifth nation to launch its own satellite
1990: STS-31 Discovery launched
Saturday 25
1962: Second Block I Saturn C-1 (SA-2) launched
1990: Hubble Space Telescope deployed
2003: ISS Expedition Seven crew launched on Soyuz TMA-2
Sunday 26
Mercury at greatest elongation (20° E)
Merucry 1.9° south of Moon
1920: Shapley-Curtis debate on the nature and distance of spiral nebulae
1993: STS-55 Columbia launched