January 09, 2009 Our Galactic Neighborhood 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.  Read More...

January 02, 2009 Standard Candles In 1929, Edwin Hubble discovered that galaxies are moving away from us by his observations of their Cepheid stars.   Read More...

December 26, 2008 X-Ray Emission from Young Stars 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.   Read More...