When Baby Planets Melt


Let’s start at the beginning.

Let’s start at the beginning. Before humans, before Earth, before any of the planets existed, there were baby planets — planetesimals. Coalesced from dust exploded outward by the solar nebula, these blobs of material were just a few kilometers in diameter. Soon, they too aggregated due to gravity to form the rocky planets in the innermost part of the solar system, leaving the early details about these planetesimals to the imagination.

Their mysterious identity is complicated by the fact that Mercury, Venus, Earth, and Mars are all different in chemical composition. Like a blender mixing the ingredients in a cake, Earth has undergone some rearrangement, largely due to volcanism and plate tectonics that shift elements into and out of the interior, that further obscures information about what the original ingredients might have been, and their proportions.

Now, a pair of MIT scientists in the Department of Earth, Atmospheric and Planetary Sciences (EAPS) have revealed some key information about those planetesimals by recreating in a laboratory the first magmas these objects might have produced in the solar system’s infancy. And it turns out, there’s physical evidence of these magmas in meteorites, adding validation to their claims.

Read more at Massachusetts Institute of Technology

Photo: Max Collinet PhD ’19 (left) and Professor Tim Grove work together to extract an experimental sample from a one-of-a-kind rock-melting machine at MIT that reveals clues about planetesimals and the formation of the rocky planets like Earth and Mars.  CREDIT: Stephanie Brown/MIT