Although astronomers have discovered more than 5,000 exoplanets, or planets outside the solar system, most of these planets are larger than Earth. This is partly because it is easier to spot large planets from great distances in space. So it’s exciting when an Earth-like planet is discovered, and the Hubble Space Telescope recently confirmed that a nearby planet, small by exoplanet standards, is 1.07 times the size of Earth.
Planet LTT 1445Ac was first discovered by NASA’s Transiting Exoplanet Survey Satellite (TESS) in 2022, but its exact size is difficult to determine due to the plane of its orbit around its star as seen from Earth. “There is a possibility that this system has a bad geometry and if that is the case, we will not be able to measure the correct size. But with Hubble’s capabilities we have reached its diameter,” said the principal investigator Emily Pass, of the Harvard-Smithsonian Center for Astrophysics, in a statement.
The new observations show that the planet is 1.07 times the diameter of Earth, making it a rocky planet like Earth with similar surface gravity. However, it is not a habitable place, because the temperature above it is 260 degrees Celsius. It is part of a triple star system located just 22 light-years away, making it one of the closest exoplanets to pass by a star.
“Moving planets are exciting because we can detect their atmospheres using spectroscopy, not only with Hubble but also with the James Webb Space Telescope,” Pass said. “Our measurement is important because it tells us that this is probably a very close terrestrial planet. “We hope to make follow-up observations that will allow us to better understand the diversity of planets around other star.”
“Hubble remains a key player in our detection of exoplanets,” said Laura Kreidberg of the Max Planck Institute for Astronomy, who was not involved in this research. “There are very few terrestrial planets close enough for us to know about their atmospheres: just 22 light years away, LTT 1445Ac is right next to the galactic term, making it which is one of the best planets in the sky.” learn about the properties of its atmosphere.