Astronomy Picture of the Day

Explanation: Where does a two-ton tiger hang out? Well, in this case the Trans-Iron Galactic Element Recorder ( TIGER) experiment hangs from a mobile crane at the far left in this panorama photo recorded last December near McMurdo Station, Antarctica. The helium-filled balloon which carried TIGER aloft for a record setting 31+ days is stretched out far to the right against the background of majestic Mt. Erebus, the southernmost active volcano in the world. While cruising with its two-ton payload above 100,000 feet, the sandwich-wrap-thin scientific balloon's fully inflated dimensions were roughly 550 by 490 feet (about as tall as the Washington Monument). TIGER was designed to detect the unexplained galactic cosmic rays -- atomic nuclei moving at near light-speed which impinge on the Earth from outside our Solar System. By making the first sensitive measurements of cosmic rays with atomic numbers between 26 (Iron) and 40 (Zirconium), TIGER investigators will seek to identify the type of astrophysical environments which could be sources of the galactic cosmic-ray material and possible ways in which the nuclei are accelerated to such high speeds.