How often do stars explode? By looking at external galaxies, astronomers can guess that these events, known as a supernovae, should occur about once every 30 years in a typical spiral galaxy like our MilkyWay. However, the obscuring gas and dust in the disk of our galaxy probably prevents us from seeing many galactic supernovae -- making observations of these events in our own galaxy relatively rare. In fact, in 1572, the revered Danish astronomer, Tycho Brahe, witnessed one of the last to be seen. The remnant of this explosion is still visible today as the shockwave it generated continues to expand into the gas and dust between the stars.Above is an image of the X-rays emitted by this shockwave made by a telescope onboard the ROSAT spacecraft. The nebula is known as Tycho's Supernova Remnant.

This sprawling dark marking is Jupiter's latest impact scar, a debris plume created as a small asteroid or comet disintegrated after plunging into the gas giant's atmosphere. Located in Jupiter's south polar region, the new feature was discovered by Australian amateur astronomer Anthony Wesley on July 19. On July 23rd Wesley's discovery was followed up by the Hubble Space Telescope with its newly installed Wide Field Camera 3, creating this sharpest view of the evolving debris plume. Estimates indicate that the impacting object itself was several hundred meters across. Similar impact markings were created when pieces of Comet Shoemaker-Levy 9 slammed into Jupiter's cloud bands in July of 1994.