The Lunar Reconnaissance Orbiter was hit by a meteoroid in 2014, and lived to tell the tale.
Brace For Impact
When you think about the risks of a meteor impact with Earth, you might think the bigger the rock the bigger the danger. It turns out that’s only part of the story.
Shattering Theory
All large asteroids have been bombarded over the ages, and as a result smaller chunks have been cast adrift in the solar system. Some of these smaller bits fall to Earth as meteorites. One of the things we notice about meteorites is that many of them have certain similarities of composition and chemical signature. As a result they can be identified into groups. This would imply that these groups have a common origin, likely a particular asteroid.
Dodgeball
Suppose you were playing a game of dodgeball. Not the typical game of dodgeball where you are part of a team trying to dodge throws from your opponents while trying to hit them out in return. This game involves you standing motionless against a wall while the other team tries to throw balls at your head. You are not allowed to move out of the way.
Impact Factor
The moon is known for its cratered surface. Its lack of atmosphere and proximity to Earth make it easy to observe impact craters from past collisions. Since the Earth and Moon are in the same general region of the solar system, they were likely bombarded at similar rates. While we do find craters on Earth (such as Barringer crater in Arizona), they are typically not as obvious due to wind and water erosion.
Hit Me
Yesterday the B612 foundation released a video showing 26 meteor impacts with energies ranging from 1 kiloton to 600 kilotons. They were detected by the global nuclear weapons test network. The claim is that these meteor impacts are occurring much more frequently than originally thought, and they are in the energy range of atomic bombs. The reality isn’t nearly so sensational.
Broken World
The view of Earth from space often evokes thoughts of an Eden. That pale blue dot that cradles humanity. But our planet’s fragile beauty was born from violent collisions large and small.
Cautionary Tale
Venus is the second planet from the Sun, and the most like Earth in terms of its mass (80% Earth’s) and size (95% Earth’s). In almost every other aspect it is radically different. It has a thick, carbon dioxide atmosphere, little water, a weak magnetic field, and a surface temperature of 740 K (860 F, 460 C). Despite this radical difference, early Venus was a wet world much like early Earth. We know from the levels of hydrogen and deuterium in Venus’ atmosphere that it too had a wet past. But somehow Venus and Earth diverged.
Rocking the Moon
Back in September of 2013 a bright flash was observed on the surface of the Moon. It was soon found that this was due to a meteor impact on the lunar surface. Now an analysis of this impact has been published in the Monthly Notices of the Royal Astronomical Society.