http://www.cfa.harvard.edu//sao/su/ Weekly Science Update en-us http://www.cfa.harvard.edu/sao/su/2009/su200906.html February 06, 2009: Nearly all galaxies are thought to have massive black holes at their nuclei, containing millions or even billions of solar masses of material. http://www.cfa.harvard.edu/sao/su/2009/su200905.html January 30, 2009: Carbon is the fourth most abundant element in the universe, and an essential constituent of life. Atomic carbon is also a critical component in the giant gas clouds that populate galaxies and from which new stars and planets are made. http://www.cfa.harvard.edu/sao/su/2009/su200904.html January 23, 2009: Oxygen is the third most abundant element in the universe (after hydrogen and helium). It is therefore thought to be an important constituent of the clouds of gas and dust from which new stars and their planets develop. http://www.cfa.harvard.edu/sao/su/2009/su200903.html January 16, 2009: When a clump of interstellar gas and dust is small and dense enough, gravity plays a decisive role in turning that material into a new star. http://www.cfa.harvard.edu/sao/su/2009/su200902.html January 09, 2009: Our Milky Way galaxy is not alone in its cosmic neighborhood. It belongs to the “Local Group,” a set of about 30 galaxies that are held together by their mutual gravitational attraction. http://www.cfa.harvard.edu/sao/su/2009/su200901.html January 02, 2009: In 1929, Edwin Hubble discovered that galaxies are moving away from us by his observations of their Cepheid stars. http://www.cfa.harvard.edu/sao/su/2008/su200852.html December 26, 2008: A newly-formed star usually has a disk of gas and dust around it. This disk (the source of possible future planets) can generate intense X-ray radiation as its material falls onto the star's surface. http://www.cfa.harvard.edu/sao/su/2008/su200851.html December 19, 2008: Eleven years ago this winter two teams of astronomers, one of them led by CfA scientists, astonished the world with their announcement that the universe would expand forever. http://www.cfa.harvard.edu/sao/su/2008/su200850.html December 12, 2008: The second brightest object in the sky outside of our solar system is the variable star CW Leo, located about 450 light-years away in the direction of the constellation of Leo (the brightest object in the sky is the southern hemisphere star called Eta Carina). http://www.cfa.harvard.edu/sao/su/2008/su200849.html December 05, 2008: Of the 300 or so extra-solar planets known, twenty-eight have been found because they transit their star (that is, their orbits take them in front of their star as seen from earth). http://www.cfa.harvard.edu/sao/su/2008/su200848.html November 28, 2008: Ultraluminous infrared galaxies ("ULIRGs") shine with the luminosity of one hundred or more Milky Way galaxies. Their most striking feature, however, is not their tremendous energy output but the fact that nearly all of their radiation is invisible, lying at infrared wavelengths. http://www.cfa.harvard.edu/sao/su/2008/su200847.html November 21, 2008: The universe contains many fabulously luminous galaxies, some of them more than a thousand times brighter than our own Milky Way. http://www.cfa.harvard.edu/sao/su/2008/su200846.html November 14, 2008: New stars tend to form with disks of gas and dust around them. After a few hundred thousand years or so, the intense ultraviolet radiation from the most massive of these stars has expelled much of the gas in the outer portion of the nearby disks, and scientist think that the escaping gas takes some of the dust along with it. http://www.cfa.harvard.edu/sao/su/2008/su200845.html November 07, 2008: When the first infrared cosmic survey satellite, IRAS, looked at the nearby star Epsilon Eridani in 1984, it found that the star emitted a large excess of cool infrared radiation. http://www.cfa.harvard.edu/sao/su/2008/su200844.html October 31, 2008: In 1998, a NASA team led by SAO astronomers launched a space mission to study water in space (and some other key molecules and atoms as well).