ANSWER: Supernova explosion
Explanation:
A series of massive supernovae explosions near our solar system have showered the earth with radioactive debris between 3.2 to 1.7 million years ago, according to a new study. Scientists have also found radioactive iron-60 in sediment and crust samples from the Pacific, Indian and Atlantic oceans.
- Supernova refers to a massive explosion of a star as it runs out of fuel and collapses
- Scientists hold that supernovae in this case were less than 300 light years away comparable to the brightness of the moon.