NASA’s Goddard Space Flight Center
An exoplanet about twice the size of Earth has been found orbiting a star called Pi Mensae about 60 light years away. It’s the first world discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS) – a spacecraft that began surveying the galaxy just two months ago.
“This is one of the first objects we looked at,” says Chelsea Huang, a TESS scientist at the Massachusetts Institute of Technology. “We were immediately saying ‘hey this is too good to be true!’”
The alien world, Pi Mensae c, takes 6.27 days to complete an orbit around its parent star, Pi Mensae. That star is so bright, it’s visible to the naked-eye from a dark-sky site in the southern hemisphere. It was previously found to have a planet the mass of ten Jupiters circling it.
Advertisement
TESS works by watching thousands of nearby stars in the Milky Way, looking for signs of planets transiting them – miniscule dips in the stars’ brightness can give away the presence of an orbiting planet momentarily passing in front of them. Such a blip in the light from Pi Mensae was identified in the first month of observations beamed home by TESS, says Huang.
The team confirmed the presence of Pi Mensae c by examining separate studies of the light of its parent star made by ground-based observatories. This analysis revealed a tiny tell-tale wobble in the star’s motion that the researchers attribute to the gravitational pull of TESS’s newly detected world.
Based on the planet’s radius it’s likely a mini-Neptune with a gaseous hydrogen and helium atmosphere, says Hugh Osborn, an exoplanet researcher at the Marseille Astrophysics Laboratory in France. “Pretty much all the planets we find at that radius have this gassy layer,” he says. “So it wouldn’t look anything like Earth.”
Reference: Arxiv, arxiv.org/abs/1809.05967
Read more: The galaxy is full of ‘water world’ exoplanets where life could evolve
More on these topics: