Because the moon is so important to life on Earth, scientists conjecture that a moon may be a potentially beneficial feature in harboring life on other planets. Most planets have moons, but Earth’s moon is distinct in that it is large compared to the size of Earth; the moon’s radius is larger than a quarter of Earth’s radius, a much larger ratio than most moons to their planets. New research finds that distinction significant.

Because the moon is so important to life on Earth, scientists conjecture that a moon may be a potentially beneficial feature in harboring life on other planets. Most planets have moons, but Earth’s moon is distinct in that it is large compared to the size of Earth; the moon’s radius is larger than a quarter of Earth’s radius, a much larger ratio than most moons to their planets.

Miki Nakajima, an assistant professor of earth and environmental sciences at the University of Rochester, finds that distinction significant. And in a new study that she led, published in Nature Communications, she and her colleagues at the Tokyo Institute of Technology and the University of Arizona examine moon formations and conclude that only certain types of planets can form moons that are large in respect to their host planets.

«By understanding moon formations, we have a better constraint on what to look for when searching for Earth-like planets,» Nakajima says. «We expect that exomoons [moons orbiting planets outside our solar system] should be everywhere, but so far we haven’t confirmed any. Our constraints will be helpful for future observations.»

The origin of Earth’s moon

Many scientists have historically believed Earth’s large moon was generated by a collision between proto-Earth — Earth at its early stages of development — and a large, Mars-sized impactor, approximately 4.5 billion years ago. The collision resulted in the formation of a partially vaporized disk around Earth, which eventually formed into the moon.

Story Source: Materials provided by University of Rochester. Original written by Lindsey Valich. Note: Content may be edited for style and length.