Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

June 10, 1999
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

Mjølnir: Impact Crater
Credit: F. Tsikalas, S.T. Gudlaugsson, J.I. Faleide, O. Eldholm (Geology Dept., Univ. Oslo)

Explanation: The stark surface of Earth's moon is pocked with large craters, records of a history of fierce bombardment by the solar system's formative debris. It may be difficult to imagine, but nearby planet Earth itself has endured a similar cosmic pounding, though oceans, weathering, and geological activity have removed or hidden many of the telltale scars. For example, this false color image produced from seismic data shows a recently discovered ringed structure about 24 miles wide on the floor of the Barents Sea. It is most probably the result of the impact, roughly 150 million years ago, of a mile or so wide asteroid-like body. Estimates indicate that the energy released in the impact could have been as high as a million megatons of TNT, resulting in immense earthquakes and tidal waves. Drawing on Norse mythology, the crater has been aptly named Mjølnir - Thor's hammer.

Tomorrow's picture: How To Make Planets

< Archive | Index | Search | Calendar | Glossary | Education | About APOD >

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.