Webb telescope detects light from an Earth-like planet
Light has been detected from a planet similar to Earth – but it has no atmosphere.
Nasa’s infrared Spitzer Space Telescope discovered several rocky exoplanets orbiting a star known as TRAPPIST-1.
But now, thanks to the James Webb Space Telescope, also known as the Webb, one of the rocky exoplanets orbiting the star has had its temperature measured.
The planet, known as TRAPPIST-1b, gives off no visible light but instead has an infrared glow.
Dr Pierre-Olivier Lagage, a co-author on the study, said: ‘There was one target that I dreamed of having.
‘And it was this one. This is the first time we can detect the emission from a rocky, temperate planet. It’s a really important step in the story of discovering exoplanets.’
The researchers found that TRAPPIST-1b is also blistering hot, clocking in at roughly around 230C – which is around the temperature of an oven.
However, even though it probably lacks an atmosphere, the planet is the first to have any form of light by an exoplanet as small and as cool as the rocky planets in our solar system, Nasa said.
Dr Thomas Greene, a Nasa astrophysicist and lead author said: ‘These observations take advantage of Webb’s mid-infrared capability.
‘No previous telescopes have had the sensitivity to measure such dim mid-infrared light.’
The find is an important step in determining whether planets orbiting small active stars like TRAPPIST-1 can house atmospheres needed to support life.
The seven planets initially caused great excitement as all the distant worlds were around the size of Earth but had an M-dwarf star – the coolest and smallest type of star – as their host.
However, TRAPPIST-1 b, is the innermost planet and receives about four times the amount of energy that Earth gets from the Sun.
Previous observations of the planet were not sensitive enough to determine if it had an atmosphere or if it was just a rocky planet, but simulations of the tide-locked planet – meaning one side always faces its host – would suggest that the planet would have a lower temperature and as the air would redistribute the heat around both sides.
However, the Webb detected a significantly hotter temperature, suggesting it has no atmosphere and, unfortunately, adds to the list of planets that cannot house humans.
The study is published in the journal Nature.