NASA APOD Astronomy Picture of the Day for 2013 August 20! It was cloudy in Missoula for the transit of Venus, so I watched it on the web. Here is a false-color RGB composite of the Sun and Venus on June 5 2012 at 23:58 UTC. Loops and prominences of hot gas are erupting into the Sun's corona, or upper atmosphere. Since the Sun's coronal gases are hotter than the 5800K (5500ºC) surface, they glow at ultraviolet "colors" instead of the surface's familiar white light. These particular wavelengths are UV light emitted by multiply ionized iron, at temperatures from 600,000K to 2,000,000K. Coloring three different B&W images red, green and blue as if they represented visible light makes a sensible color image out of normally invisible light. Quick link to highest resolution version. Original extreme UV images at 171Å (B), 193Å (G) and 211Å (R) are from the SDO (Solar Dynamics Observatory) satellite's AIA (Atmospheric Imaging Assembly) camera. Source images courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.
