Scientists have revealed a promising development in the search for extraterrestrial life.
By studying NASA satellite data, experts from the University of Warwick have found a further 85 ‘exoplanets’ – planets outside our solar system.
Their size ranges from about 18,000 kilometers to a whopping 350,000 kilometers in diameter – so they are all larger than Earth (just under 13,000 kilometers).
But like Earth, they are potentially the right distance from their host stars to have a temperature that supports life – the so-called ‘habitable zone’.
More than 5,000 exoplanets have been discovered so far, but it is still uncertain which ones harbor alien life forms.
Exoplanets are simply planets outside our solar system. They could indicate whether aliens exist (archive photo)
The new study was led by PhD student Faith Hawthorn at the University of Warwick’s Department of Astronomy and Astrophysics.
‘All exoplanets are in 85 unique systems – one planet per star,’ she told MailOnline.
“Some of them may be rocky, some may be gaseous.
‘It’s quite rare for habitable planets to be discovered; you need a very specific set of conditions for habitability, and future work is needed to confirm this.”
Dr. Hawthorn and colleagues used NASA’s Transiting Exoplanet Survey Satellite (TESS), which launched in 2018, to monitor the sky for changes in the brightness of the nearest stars.
Many astronomers search TESS data for “transits”: periodic dips in starlight that indicate a planet crosses and briefly blocks the light from its star.
Using the transit method, experts can not only find planets but also deduce certain details about them, such as their size and how long it takes to orbit their star.
How long an exoplanet’s orbit lasts can in turn reveal the planet’s distance from its star – because the longer an orbit lasts, the more distance it has had to travel.
In general, if a planet is a similar distance from its star as Earth is from the Sun (150 million kilometers), scientists could reasonably suggest that it is neither too hot nor too cold – and therefore could be habitable.
However, there is still a lot that Dr Hawthorn and colleagues don’t know about the new exoplanets, including their exact distances to stars.
“There is plenty of room for further research into these exoplanets – to learn more about their exact orbital periods, whether or not they have moons and what exactly they are made of,” she said.
NASA’s Transiting Exoplanet Survey Satellite (TESS) was launched in 2018 to monitor the sky for changes in the brightness of the nearest stars. It is pictured here before launch
The planets were discovered using the transit method: when a planet passes between a star and its observer, resulting in light dips (photo)
Compared to most exoplanets found so far by the TESS project, these 85 exoplanets have a longer orbital period and are therefore much cooler.
The scientists know this because the planets orbited their star only twice during a given study period, instead of three times like exoplanets previously discovered by TESS.
A preliminary estimate shows that the 85 exoplanets take between 20 and 700 days to orbit their host stars, while most exoplanets observed by TESS have an orbital period of only 3 to 10 days.
‘We know the most likely time for an orbit, but it has not yet been confirmed – and this provides information about the distance to the star,’ Dr Hawthorn told MailOnline.
The team admits that of the total 85 exoplanets, 60 are brand new discoveries, while 25 have also been detected in the TESS data by other research teams using various search techniques.
At this stage they have yet to be definitively confirmed by NASA as exoplanets, but the researchers hope that this will be achieved with future observations.
NASA defines confirmed exoplanets as ‘planets validated by two or more discovery methods’.
‘Future work from other research groups might be able to confirm the planets – a planet is considered “confirmed” if it has a mass (we only have their size, not their mass),” Dr Hawthorn told MailOnline.
As of January 2024, more than 5,500 exoplanets have been discovered and confirmed since the very first one in 1992.
The more than 5,000 exoplanets confirmed so far in our Milky Way include all types, including a mysterious variety known as “super-Earths” because they are larger than our world and may be rocky.
According to NASA’s online exoplanet database1,912 of the exoplanets are like Neptune, 1,772 are gas giants like Jupiter, 1,679 are super-Earths and 199 are rocky.
But NASA insists this is only “a small fraction” of all the planets in the Milky Way galaxy alone, which could number hundreds of billions.
Considering that there are an estimated 2 trillion galaxies in the observable universe, there could be 1,000,000,000,000,000,000,000,000 planets.
The new study was published today in the Monthly Notices of the Royal Astronomical Society (MNRAS).