This is an artist’s concept of the nearby exoplanet, LTT 1445Ac, which is the size of Earth.
Astronomers using NASA’s Hubble Space Telescope have measured an exoplanet and found it to be almost exactly the same size as Earth. However, despite it being Earth-sized, with a rocky surface and nearly the same surface gravity, it’s not reckoned to be Earth-like, with surface temperatures around 500 degrees Fahrenheit (260 degrees Celsius). That’s hotter than a pizza oven, according to NASA.
An exoplanet is a planet orbiting a star other than Earth. According to NASA, over 5,000 have been found, all of them discovered since the 1990s, though astronomers think there could be 100 billion in our Milky Way galaxy.
A Nearby Earth-Sized Rocky Planet
The exoplanet is called LTT 1445Ac and is just 22 light-years away in the constellation Eridanus. It orbits a red dwarf star, much smaller and cooler than our sun, every 3.1 Earth days, according to NASA. Red dwarf stars make up around 70% of all the stars in the Milky Way. However, this star exists in a triple star system, with two closely orbiting red dwarfs.
In a paper published today in The Astronomical Journal, scientists reveal that over six orbits of Earth, the Hubble Space Telescope nailed its diameter at just 1.07 times Earth’s.
Data collected during six orbits of the Hubble Space Telescope enabled scientists to calculate the ... [+]
Discovered Last Year
LTT 1445Ac was first discovered last year by NASA’s Transiting Exoplanet Survey Satellite. TESS uses the transit method to find exoplanets, detecting changes in the light of a star as a planet crosses in front of its disk. Once found, scientists can point a space telescope at an exoplanet during another transit to work out its size and study its atmosphere by collecting and analyzing the starlight light coming through it—a technique called spectroscopy.
“Transiting planets are exciting since we can characterize their atmospheres with spectroscopy, not only with Hubble but also with the James Webb Space Telescope,” said Emily Pass of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.
Our measurement is important because it tells us this is likely a very nearby terrestrial planet,” said Pass.
An Exciting Close Target For JWST
The authors call LTT 1445Ac an exciting target for future atmospheric studies because it’s so close to Earth. “There are precious few terrestrial planets that are close enough for us to learn about their atmospheres,” said Professor Laura Kreidberg of the Max Planck Institute for Astronomy in Heidelberg, who was not part of this study. “At just 22 light years away, LTT 1445Ac is right next door in galactic terms, so it’s one of the best planets in the sky to follow up and learn about its atmospheric properties.”
Wishing you clear skies and wide eyes.
