'Garnet Planets' Would Be Hostile to Life

Earth's surface is ever-changing, with tectonic plates bumping together to cause earthquakes and volcanoes, grow mountains and replenish and redistribute elements — and that dynamic environment helps life thrive. Planets are mostly made of the same stuff as their stars, and researchers have used that fact to simulate two very different rocky planets: one whose upper mantleis mostly the mineral olivine, like Earth's, and one with a stiff upper mantle made of garnet. According to Johanna Tes