Artist’s impression of the exomoon candidate Kepler-1625b-i, the planet it is orbiting and the star. (NASA/ESA/L. Hustak, STScI)
“Moons are where planets were in the 1990s,” predicted René Heller from the Max Planck Institute for Solar System Research a few years ago. “We’re on the brink.”
Heller was predicting that we were close to the first discoveries of exomoons: moons that orbit extrasolar planets outside our solar system. When a possible exomoon detection was announced in 2017, Heller’s prediction was proved correct. Not only had we found a candidate moon, but its properties defied our formation theories just as with the discoveries of the first exoplanets.
However, a paper published in Science this month has proposed a method for building this most unusual of moons.
As we move away from the sun, the planets of our solar system become mobbed with moons. How these small worlds formed is attributed to three different processes:
Moons in our solar system are thought to have formed through three different mechanisms (E. Tasker / Many Worlds)
The most extensive moon real estate orbits our gas giants, Jupiter, Saturn, Uranus and Neptune. The majority of these moons are thought to have been born during the ...