What's in the sky tonight?
December 5, 2012
-Ganymede, the largest satellite of Jupiter, crosses Jupiter's face tonight from 9:25 to 11:17 p.m. EST, closely followed by its black shadow from 9:37 to 11:44 p.m. EST. In amateur telescopes, Ganymede's shadow will be much more obvious against Jupiter's bright surface than Ganymede itself is.
-Under the "Upcoming Events" tab, you can now observe the positions of both Ceres and Vesta until March.
Astro Picture of the Day:
December 5, 2012
Source:
Why does this galaxy emit such spectacular jets? No one is sure, but it is likely related to an active supermassive black hole at its center. The galaxy at the image center, Hercules A, appears to be a relatively normal elliptical galaxy in visible light. When imaged in radio waves, however, tremendous plasma jets over one million light years long appear. Detailed analyses indicate that the central galaxy, also known as 3C 348, is actually over 1,000 times more massive than our Milky Way Galaxy, and the central black hole is nearly 1,000 times more massive than the black hole at our Milky Way's center. Pictured above is a visible light image obtained by the Earth-orbiting Hubble Space Telescope superposed with a radio image taken by the recently upgraded Very Large Array (VLA) of radio telescopes in New Mexico, USA. The physics that creates the jets remains a topic of research with a likely energy source being infalling matter swirling toward the central black hole.