A new telescope will be able to analyse the atmospheres of Earth-like exoplanets and further study the universe using infrared wavelengths, according to the results of a recent study.
Due to be launched in 2018, the James Webb Space Telescope (JWST) is a successor to the Hubble telescope. Its use of infrared wavelengths means that it will be able to differentiate between a planet with a moderate, Earth-like atmosphere and more extreme and volatile ones, such as Venus. Current telescopes can only determine exoplanets’ size and presence and their distance from a star.
Oxford University’s Dr Joanna Barstow, who conducted the study, said: “A planet’s atmosphere provides a good guide to likely conditions on the surface. The Earth’s atmosphere contains significant amounts of nitrogen, oxygen, ozone and water. By contrast, its inhospitable ‘evil twin’, Venus, has an atmosphere made mostly of carbon dioxide, which drives its surface temperature to a blistering 450 degrees Celsius.”
The JWST will be able to determine if a newly discovered planet has a climate similar to that of the Earth, but only if they are orbiting a star that is smaller and redder than the Sun.
Barstow said: “If we took the Earth and Venus and placed them in orbit around a cool, red star that’s not too far away, our study shows that JWST could tell them apart. Earth’s ozone layer, 10 kilometres above the surface, is produced when light from the Sun interacts with molecules of oxygen in our atmosphere and it produces an unmistakable signal that could be detected by JWST. Venus, without a substantial ozone layer, would look very different. That’s assuming that planets starting out like Earth and Venus would evolve in the same way around a cool star!”
In order to detect exoplanets, astronomers would need to study the potential planet at least 30 times, but the JWST is expected to be used for additional astronomical purposes.
“Future telescopes that are dedicated to observing the atmospheres of many rocky planets around different stars will be required to fully resolve the question of habitability on exoplanets. In the meantime, JWST will observe many other weird and wonderful planets in unprecedented detail,” said Barstow.