They are believed to come from asteroids Vesta The difference between the two periods is only the parent rocks from different geological history. from Radioisotope The ages of these meteorite crystals are between 44.3 and 4.55 billion years. In comparison, they are very common types, accounting for 5% of all meteorites found, and accounting for Amedrite 60%.
They may be created by Vesta come earth ： - one
Vesta was hit and ejected debris, producing V-type asteroid fragment. No matter what is thrown out is a large asteroid or becomes a small fragment, some small asteroids Vesta family The others are further scattered everywhere. These events are believed to have occurred no more than one billion years ago, including a huge impact. The huge crater in the southern hemisphere is the best evidence of the location of this impact point. It also requires multiple impacts to eject rocks up to the number of V-type asteroids we know. - two
Some asteroid fragments have gone through a long journey into 3:1 Kirkwood gap 。 because Jupiter Strong perturbation. This is an unstable region. The asteroid here will be thrown away in a different orbit after about one million years. Some are perturbed and enter the orbit close to the earth, forming a small V-shape Near Earth Asteroids , e.g. (3551) Verenia 、（3908） Nyx ,, and (4055) Magellan 。 - three
Then smaller impacts on these near Earth objects smashed them into meteorite sized rocks, some of which later arrived on Earth. according to cosmic rays According to the measurement of exposure, most HED meteorites came from several different types of impact events, and it took 6 million to 73 million years in space to hit the Earth.
