Earthlike Planets Could Have Formed at Almost Any Time in the Milky Way’s Evolution | ScienceDaily
Building a terrestrial planet requires raw materials that weren’t available in the early history of the universe. The Big Bang filled space with hydrogen and helium. Chemical elements like silicon and oxygen - key components of rocks - had to be cooked up over time by stars. But how long did that take? How many of such heavy elements do you need to form planets, especially rocky, Earthlike planets?
Studies have shown that Jupiter-sized gas giants tend to form around stars containing more heavy elements than the Sun. However, research by a team of astronomers found that planets smaller than Neptune are located around a wide variety of stars, including those with fewer heavy elements than the Sun. Astronomers call chemical elements heavier than hydrogen and helium “metals.” As a result, rocky worlds like Earth could have formed earlier than expected in the universe’s history.
"Terrestrial worlds could form at almost any time in our galaxy’s history," said Smithsonian astronomer David Latham (Harvard-Smithsonian Center for Astrophysics). “You don’t need many earlier generations of stars.”Latham played a lead role in a study released this past April, which was led by Lars A. Buchhave from the University of Copenhagen.