Astronomers have discovered an exoplanet far outside the Milky Way for the first time.
The world, the size of Earth’s moon, orbits a sun-like star in our local galaxy, the Local Group, and may be home to alien life.
There are billions of stars in the Milky Way, but it is only when a star crosses our solar system that we can detect life on its planets.
Why did we find this exoplanet?
Researchers identified the exoplanet by studying light from a star that is only 2.6 billion miles away from us, but a star similar to our sun.
They were watching out for a changing dimming in a star’s light as it passed between Earth and the star— when the planet slipped out of view.
Their observations from 2015-2016 show that the planet is 1.6 times the diameter of Earth and orbits its star at 40 million miles from the star.
How big is the exoplanet?
The exoplanet is 750 million kilometers—roughly equivalent to the distance from the Earth to Jupiter—from its star. The moon is one hundred and six million kilometers away from our planet.
I’m left wondering how the planets in this system could possibly become habitable.
While it is possible that the planet is tidally locked to its star, the old joke in astronomy is that you can pick your sun based on how much your left and right eye are in dialogue.
Turns out this planet would actually make a great home for what would likely be life on the outside of the Milky Way. The property of the exoplanet allows for extensive exploration through telescopes and other instruments with higher precision.
Why find exoplanets?
All planets outside our solar system are potentially habitable but their existence is usually only discovered when a giant planet passes in front of its star, blocking more of the star’s light than the star’s natural brightness changes.
The researchers speculated that the exoplanet may be a rocky planet with a thick atmosphere and may be in the process of growing since it rotates in an elliptical orbit rather than the circular orbit of our own solar system.
“The surprising thing about this discovery is how similar its characteristics are to those of our sun,” said lead researcher Sarah Pierce from the National Aeronautics and Space Administration’s Goddard Space Flight Center in Greenbelt, Maryland.
It is likely that planets of this size are only common in the Milky Way’s Local Group, which is a cluster of nearly 100 sun-like stars in the Perseus Cluster.
The Exoplanet Hunters Project was funded by the NASA Exoplanet Exploration Program.