How Young is the Lunar Crater Giordano Bruno?

1
How Young is the Lunar Crater Giordano Bruno?

• Is it possible that people witnessed the impact
  event that made this crater in the year 1178 or
  did it form long, long ago?
• Small craters on its ejecta blanket were counted
  to derive a formation age of Giordano Bruno.

2
How Young is the Lunar Crater Giordano Bruno?

• On the left chart, the crater size-frequency
  distribution for small craters counted on the
  ejecta blanket of Giordano Bruno falls between 1
  to 10 million years, not younger.
• On the right, Giordano Bruno plots at 4 million
  years on this lunar cratering chronology.

3
How Young is the Lunar Crater Giordano Bruno?

• Complication Some or all of the small craters
  could be secondary craters formed by the Giordano
  Bruno event.
• Counting secondaries leads to an overestimate of
  the age.
• But is Giordano Bruno 2 million or 832 years old?

Example of cluster of secondary craters on the
farside of the Moon