In January of 2000, a large meteorite exploded over British Columbia, with fragments landing over the frozen surface of Tagish Lake. After careful analysis, it has been discovered that the meteorite is the first documented object to travel to Earth from the edge of the solar system.
Finding an object coming from the Kuiper Belt, the region beyond the orbit of Neptune, is not just a curious discovery, it actually reinforces the theory of a primordial squabble between the four gas giant planets (Jupiter, Saturn, Uranus, and Neptune) and a mysterious fifth one that was kicked out.
Researchers from Charles University in Prague and Southwest Research Institute in Boulder, Colorado, have released a study, published in the Astrophysical Journal, that tries to explain the origin of the Tagish Lake meteorite. According to their research, evidence of a population of primordial Kuiper belt objects (KBOs) in the inner solar system can only be explained by some bygone gravitational instability.
The team modeled how these KBOs, many of which are D-type asteroids, moved from the edge of the solar system to the asteroid belt, which is between the orbit of Mars and Jupiter. It is believed the Tagish Lake meteorite is a fragment of one of these D-type asteroids.
By simulating the young solar system and including a fifth planet the size of Neptune, the researchers were able to get the right amount of D-type asteroids near Earth. These asteroids couldn't have formed where they are now found, so a mechanism must have moved them closer. Jupiter and Saturn kicking out a fifth planet seems to produce the right amount of disturbance.
“For a short time in the solar system’s history, you have giant planets encountering one another while surrounded by this big sea of comets," co-author Bill Bottke told New Scientist. "Things were very dramatic for a short time."
The meteorite is considered one of the best preserved in the world, with very little contamination from terrestrial life. It is a fragment from the very dawn of the solar system, and the closest we can get to analyze a bit of Pluto, Eris, or Makemake.
The Tagish Lake has already been in the news for being rich in amino acids, the molecules that make proteins, and for showing evidence that its parent asteroid was probably rich in water. Scientists are considering the possibility that this class of asteroids played a role in the abundance of water and life molecules on Earth.
[H/T: New Scientist]