Published on April 23, 2016 by Jacqueline Taylor  
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On the left is Supernova 1987A after the star has exploded. On the right is the star before it exploded. Credits: NASA
New findings on the moon suggest that there may have been a supernova occurrence close to our solar system 2 million years ago. A supernova is the event of a star exploding due to a change in its core, whether from its natural death process, or by extra matter accumulation from another star. It has been theorized that supernovas could be the cause of some of Earth’s mass extinctions due to the highly intense radiation emitted during these events. Heavy elements are also emitted when stars explode, such as radioactive isotope iron-60, which has a half-life of 2.6 million years. This element has been found in Earth’s deep seas, and now recently on the moon, which would suggest our solar system was once within a star’s blast zone. The best evidence for this theory comes from the moon due to its relatively untouched surface that can provide more accurate measurements. The data comes from the Apollo missions where lunar soil was gathered and analyzed using accelerator mass spectrometry. The ratio was found to have a high concentration 10 times higher than the measured background, ruling out cosmic ray interactions as a possible source of the isotope.