The exoplanet does not rotate, with one side perpetually in daylight.
Astronomers have discovered an Earth-size planet outside the Solar System. Named LP 791-18 d, the exoplanet is likely covered in volcanoes and has been tormented by eruptions, according to a report in CNN. The volcanoes are similar to those discovered on Jupiter's moon Io, the most volcanically active place in our Solar System, the outlet further said. Astronomers used data from NASA's planet-hunting Transiting Exoplanet Survey Satellite, the retired Spitzer Space Telescope and some other ground-based telescopes. A study about the exoplanet's discovery has been published in the journal Nature.
Spitzer's observations of the system were among the last the satellite collected before it was decommissioned in January 2020, NASA said on its website.
LP 791-18 d is located about 90 light years, the distance travelled by light in a year (9.5 trillion kilometres), from Earth in the Crater constellation and orbits a red dwarf star.
Two other planets also orbit the star, including LP 791-18 b, which is estimated to be 20 per cent bigger than Earth, the study further said.
Due to the proximity with these stars, planet d's orbit path shifts, becoming slightly more oval-shaped. The elliptical revolutions cause the interior of the planet to heat up, driving volcanic activity.
"There is not yet any direct observational evidence of exoplanet volcanism, but this planet is a particularly likely candidate," said University of Kansas astronomy professor Ian Crossfield, one of the authors of the research.
The similar phenomenon afflicts Io, which is caught in a gravitational crossfire between Jupiter and its larger moons, the CNN report further said citing the study.
LP 791-18 d does not rotate, with one side perpetually in daylight and the other in darkness.
In our Solar System, Earth and Venus are the volcanically active planets.