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Venus Transit Recalls Adventures of Yore
June 5, 2012
Today's transit of Venus, in which our sister planet appears to cross the disk of the sun, will be the last till 2117. As observatories and millions of people watch the rare planetary alignment, few may know the stories of astronomers who predicted them and explorers who risked life and limb to observe them.
Observations Upset Models of Stellar Evolution
December 22, 2011
Stellar evolution models go back decades. Ever since the Hertzsprung-Russell diagram came out in 1910 (graphing temperature against luminosity), showing most stars fell on a line called the “main sequence”, astrophysicists have sought to understand the life cycle of stars from birth to death. In general, the story goes, collapsing clouds of gas and dust produce main-sequence stars that burn nuclear fuel till they run out. Depending on their masses, they end up as supernovae, red giants or slowly-cooling cinders. While red dwarfs cool down slowly into the darkness, supernovae and red giants eject mass outward into space . Two new planets found close to a red giant are among new headaches for theorists.
It’s Still a Rare Earth
September 25, 2011
Now that hundreds of extrasolar planets are known, how do they compare to ours? The Kepler spacecraft has found a varied assortment of all sizes and distances away from their parent stars. Only a few reside in their star’s habitable zones. But that’s only the first of many requirements for life. Two recent studies indicate that Earth remains a rare bird in the celestial aviary.