What does the acronym HED stand for in meteorite classification?
HED stands for howardite, eucrite, and diogenite. This acronym defines a specific clan of achondrite meteorites that make up about 5% of all falls to Earth.
Questions about HED meteorite
Short answers, pulled from the story.
Where did HED meteorites originate before reaching Earth?
All members of this meteorite family trace their roots to the crust of asteroid Vesta. No matter their final composition on Earth, they share a common birthplace in space.
When were HED meteorites formed according to radioisotope dating?
Radioisotope ratios confirm these crystallization ages fall between 4.43 billion years and 4.55 billion years. These dates place the formation of the parent body near the dawn of our solar system.
How long do most HED meteorites travel through space before impacting Earth?
Most HED meteorites spent between 6 million and 73 million years traveling through space before impacting Earth. Cosmic ray exposure measurements provide the data for this duration estimate.
Why are there differences in chemical makeup among HED meteorites?
Differences in chemical makeup result from ejection at different moments during Vesta's geologic history. Scientists believe these rocks arose from several distinct impact events rather than a single explosion.