TESS has found its first planet within the Goldilocks zone
The Transiting Exoplanet Survey Satellite spotted the planet just over 100 light-years away
NASA’s Transiting Exoplanet Survey Satellite (TESS) has spotted its first potentially habitable planet in a star’s ‘Goldilocks zone’, where conditions are just right to allow the existence of liquid water and therefore life.
Named TOI 700d, the planet is the latest in a handful of potentially habitable Earth-sized worlds found throughout the Galaxy. It is around 20 per cent bigger than Earth, completes its orbit every 37 days and receives 86 per cent of the energy from its star that the Sun provides to Earth.
It is the outermost planet found in orbit around the star TOI 700, which is a small, cool, dwarf star located just over 100 light-years from Earth in the southern constellation Dorado. TOI 700 is roughly 40 per cent of the Sun’s mass and size, and about half its surface temperature.
“TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars,” said Dr Paul Hertz, astrophysics division director at NASA in Washington. “Planets around nearby stars are easiest to follow up with larger telescopes in space and on Earth. Discovering TOI 700d is a key science finding for TESS. Confirming the planet’s size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January.”
TESS views large swathes of the sky, called sectors, for 27 days at a time. This long period of observation allows the satellite to monitor changes in a star’s brightness caused by an orbiting planet crossing in front of its star from our perspective, an event called a ‘transit’.
While the exact conditions on TOI 700d are a mystery, a team of researchers at NASA’s Goddard Space Flight Center used known information, such as the planet’s size and the type of star it orbits, to generate a series of computer models and make predictions. One simulation revealed an ocean-covered world surrounded by a dense, carbondioxide-dominated atmosphere, similar to what scientists suspect surrounded Mars when it was young. Another model depicts TOI 700d as a cloudless, all-land version of modern Earth.
“It’s exciting because no matter what we find out about the planet, it's going to look completely different from what we have here on Earth,” said Gabrielle Englemann-Suissa, who led the computer modelling team.