This year, Mars reaches its long-awaited opposition on July 27—and is visible all night. Look for its south polar cap and dark features that shift as the planet rotates. You will also spot constellations Scorpius and Sagittarius, and the annual Delta Aquarid meteor shower.

“Tonight’s Sky” is produced by HubbleSite.org, online home of the Hubble Space Telescope. This is a recurring show, and you can find more episodes—and other astronomy videos—at http://hubblesite.org/videos/science

This animation shows the remnant of Kepler’s Supernova, shown first in infrared, then visible, then low energy X-ray, then high-energy X-ray emission and finally in combination.

In 1604, astronomer Johannes Kepler noted the appearance of a new bright object in the sky, visible to the naked eye for the next 18 months. Today we know that he was seeing the death of a star 20,000 light years from Earth. It was more than ten times the mass of our sun.

Now, more than four hundred years later, several of NASA’s Great Observatories combined to produce a multi-wavelength image of the expanding remnant. Although the initial blast was caused by the implosion of the star core that rebounded to violently eject material. The supernova today can be seen as it impacts surrounding material that was likely ejected in previous episodes of losing mass into space.

The multiple wavelengths show separated layers of emission that represent different portions of the impact. Infrared (Spitzer) traces the coolest material as it is heated by the ejecta. The optical emission (Hubble) traces hot (several thousand degree) gas that is excited by the collision. The lower energy X-ray (Chandra) represents much hotter gas – up to a few million degrees, Fahrenheit, similar to the hot corona of our sun. The highest energy X-ray emission can reach tens of millions of degrees. This emission is closest to the most powerful portions of the expanding blast wave. The observations reveal that Kepler’s supernova was a “Type Ia” – a supernova caused by the transfer of material between two smaller dwarf stars. The added material brings the total mass of one of the stars beyond the critical threshold for supernova collapse.

Video: NASA, ESA, and G. Bacon (STScI)
Images: NASA, ESA, R. Sankrit and W. Blair (Johns Hopkins University)