Recently a paper in Science looked at the magnetic properties of a primitive meteorite known as Semarkona, and discovered a surprising fact about the early solar system.
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.
Thor’s Hammer
Imagine if a Tunguska event occurred every 5 years or so. Every few years, and some part of the planet gets a crater, or an airburst. Most would be in remote areas, but some wouldn’t. Of course we know that meteors follow a power law distribution in size distribution. So for every Tunguska event, there would be thousands of Chelyabinsks. So perhaps 200 of them every year. Then there are the larger ones. Big impacts creating 10km-wide craters every century or so. And the ever larger ones every millennia. Now imagine Earth gets pummeled at this rate for 200 million years.
Rare Earth
About 1.85 billion years ago, in what would come to be known as Sudbury Canada, a 10 kilometer wide asteroid struck with such energy that it created an impact crater 250 kilometers wide. Today the chief industry of Sudbury is mining, all because of that ancient impact. In fact much of the mining industry is possible because of asteroid impacts in Earth’s early history.
A Rusted Development
Of the tens of thousands of meteorites that have been discovered on Earth, about a hundred came from Mars, such as the one pictured here. We know they originated from Mars because their composition is different from other meteorites, and they correlate with the atmospheric and geological composition of Mars as determined by the Martian landers. They are currently the only martian material to which we have direct access.
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.
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.
Synthetic Tracking
A recent paper in the Astrophysical Journal presents a new method that could make finding smaller meteors easier. Instead of using long exposures to look for meteor trails, the method uses a series of short exposures and some computational power to produce synthetic tracking.