‘Neptune-like’ planet could reveal solar system secrets
Scientists have found a planet that looks like our Neptune and might answer some of the most fundamental questions of the planets. The new discovery sits 430 light years from Earth and has clear skies and an atmosphere that’s almost entirely made up of hydrogen and helium.
It is the same size as Neptune, but it is being referred to as warm, because it is much closer to its parent star. It might help shine a light on how solar systems first form, and how they go on to develop over time.
The planet has a primitive, watery atmosphere that suggests that it formed either near its star, or relatively
late in the time of its solar system. That is vastly different from Neptune and Uranus, which were created early on in the edge of the disc of dust and gas that swirled around our own young sun. Learning about those differences – and how the planet was formed – could help us understand how our own solar system came to be.
Professor David Sing from the University of Exeter, whose team carried out a detailed study of the planet together with scientists from Nasa, said: “This exciting new discovery shows that there is a lot more diversity in the atmospheres of these exoplanets than we have previously thought. This ‘warm Neptune’ is a much smaller planet than those we have been able to characterise in depth, so this new discovery about its atmosphere feels like a big breakthrough in our pursuit to learn more about how solar systems are formed, and how it compares to our own.”
The scientists analysed data from Nasa’s Hubble and Spitzer space telescopes to measure light filtering through the planet’s atmosphere as it passed in front of its host star. The findings, published in the journal Science, provide enough detail to show that the planet, named HAT-P-26P, has skies relatively clear of clouds and a strong water signature.
Co-author Dr Hanna Wakeford, from Nasa’s Goddard Space Flight Center in Greenbelt, Maryland, said: “Astronomers have just begun to investigate the atmospheres of these distant Neptune-mass planets, and almost right away, we found an example that goes against the trend in our solar system.”