The solar system was formed some 4.6 billion years ago when a small part of a giant molecular cloud collapsed due to gravity. This resulted in the formation of larger objects. Some of these objects became planets, dwarf planets, and moons. The remaining pieces formed asteroids, comets, meteoroids, and small moons. But among all, only Earth was life-supporting.This has bothered scientists for a long time, but a new study has hinted at the reasons behind Earth being the only one that is home to life.
According to a study, the building blocks of life were supposedly transported by meteorites. These meteorites were possibly the remains of early “unmelted asteroids”—a type of planetesimal. These small rocky planets are solid objects made of rock and ice that are the building blocks of planets. They form in protoplanetary disks around developing stars when dust and ice particles clump together.
A team of researchers has traced the chemical element zinc in meteorites to uncover the source of Earth’s “volatiles”—elements or compounds that easily evaporate at low temperatures. These volatiles are crucial because they include six key chemicals essential for life, such as water. By studying meteorites, scientists hope to better understand how these life-sustaining compounds arrived on our planet. This might also give a clue into how life originated here or might emerge elsewhere.
The researchers from Cambridge and Imperial College London chose zinc because it is found in a composition that can help easily identify the origins of volatiles. Zinc on Earth came mainly from two regions in the solar system—one from the inner region of the solar system, and the other from beyond Jupiter.
Planetesimals are of different kinds: the ones that formed in the earliest era of the solar system and were thus exposed to the strong radiation of the infant Sun. As a result of vaporization, they lost volatiles. Another kind of planetesimal was born later and thus held on to their volatiles. As the team studied zinc in different meteorites and traced their origins, they detected that zinc reached Earth over 10 million years ago. Around 90% of the zinc originated from “unmelted” planetesimals. Furthermore, it is probable that these unmelted space rocks or planetesimals likely also delivered a lot of volatiles to the forming Earth.
