
Astronomers have spotted a star system with planets that could support life just 39 light years away.

Seven Earth-like planets have been discovered orbiting nearby dwarf star 'Trappist-1', and all of them could have water at their surface, one of the key components of life.

Three of the planets have such good conditions, that scientists say life may have already evolved on them.

Researchers claim that they will know whether or not there is life on any of the planets within a decade, and said 'this is just the beginning.'

No other star system discovered before has been found to have such a large number of Earth-sized planets.

The planets likely have rocky compositions like Earth, are around the same size as our planet, and six have surface temperatures between 0-100°C (32-212°F).

This gives these planets some of the vital atmospheric conditions needed to grow biological life.

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The Trappist-1 star, an ultra-cool dwarf, has seven Earth-size planets orbiting it. This graphic shows how the outer orbiting 1h is an icy planet, while inner orbiting 1b, 1c and 1d are likely to be hot and dry. Though the researchers claim that all seven planets could feasibly have water at their surface, it is planets 1e, 1f, and 1g that are most likely to have water oceans

KEY POINTS - Newly discovered star system is just 39 light years from Earth - Seven Earth-sized worlds are orbiting a dwarf star known as Trappist-1 - Six inner planets lie in a temperate zone where surface temperatures range from 0-100°C (32-212°F) - Of these, at least three are thought to be capable of having oceans, increasing the likelihood of life - Scientists say life may have already evolved on at least three of the planets - No other star system known contains such a large number of Earth-sized and probably rocky planets - They were found using the 'transit' method that looks for tiny amounts of dimming caused by a world blocking light from its star Advertisement

The researchers suggest that three of the seven planets, found in the system's 'habitable zone', could have oceans of water with life evolving on them already.

'We now have seven planets that we can study in detail for life, and this is something we are already doing,' lead-author Michaël Gillon, an astronomer at the University of Liège, Belgium, said.

'People will hear more and more about this system in the coming months and years.'

Each planet, labelled 1b-1h, was found via telescopes using the 'transit' method.

This is when the orbit and other properties of planets are measured as they pass in front of their star, causing it to briefly dim.

An international group of researchers used a series of space and ground-based telescopes to find the seven planets in the Trappist-1 system.

Telescopes used include a telescope owned by Liverpool John Moores University in La Palma, as well as Nasa's Spitzer Space Telescope found in Earth's orbit.

The researchers measured the 'transits' of planets by taking measurements of dips in the Trappist star's brightness as planets passed in front of it.

This chart shows, on the top row, artist impressions of the seven planets of Trappist-1 with their orbital periods, distances from their star, radii and masses as compared to those of Earth. The bottom row shows data about Mercury, Venus, Earth and Mars. The seven planets' orbits are closer to their star than Venus, Earth or Mars, and are therefore significantly shorter

Earth and the Trappist-1 system are both located in the Milky Way galaxy, which measures around 100,000 light years across. Trappist-1 is 39 light years from Earth, making it a close neighbour of our planet. Despite this, experts suggest that it would take humans hundreds of thousands of years to reach the new system using current technology

THE SEVEN NEW PLANETS IN THE TRAPPIST-1 SYSTEM Name Orbit (days) Mass (where 1.0 = mass of Earth) Distance to star (millions of miles) Distance to star (millions of km) Possibility of hosting alien life 1b 1.5 0.85 1.02 1.64 Less likely - too hot 1c 2.4 1.38 1.39 2.24 Less likely - too hot 1d 4 0.41 1.95 3.14 Less likely - too hot 1e 6 0.62 2.6 4.19 Most likely 1f 9.2 0.68 3.44 5.53 Most likely 1g 12.3 1.34 4.18 6.73 Most likely 1h 20 unknown 5.58 8.97 Less likely - too cold

IS THERE LIFE IN THE TRAPPIST-1 SYSTEM? Though all seven planets could have liquid water, three of them - 1e, 1f, 1g - have the right atmospheric conditions to hold oceans of water at their surface. These oceans may have already evolved life, though co-author Dr Amaury Triaud told MailOnline that the researchers cannot possibly know at what stage this life might be. 'We only know the star is older than half a billion years and likely the planets are too, so far we do not know if there is liquid water and even less if there is life,' he said. The team have already begun using larger telescopes positioned across the globe to search the atmospheres of the planets for signs of life. 'Several different molecules and relative make-ups of atmosphere will allow us to conclude that there is biological life present,' lead-author Dr Michael Gillon said. 'The presence of methane, water, oxygen, and carbon dioxide are all strong indicators.' The team say that they will know if biological life exists on the planet within a decade. While the Trappist-1 star is not young at half a billion years old, the system is burning through its hydrogen reserves at a slow pace. Astronomer Professor Ignas Snellen of the Netherlands's Leiden University, not involved in the study, claims that the system has great potential for evolving life in the future. 'In a few billion years, when the sun has run out of fuel and the solar system has ceased to exist, Trappist-1 will still be only an infant star,' she writes in a Nature News and Views article. 'It burns hydrogen so slowly that it will live for another 10 trillion years, more than 700 times longer than the universe has existed so far, which is arguably enough time for life to evolve.' Advertisement

Using these transits they discovered seven planets whose orbits are close enough to the Trappist-1 star that they could have water at their surface.

It is likely that all of these planets have one side perpetually facing their star.

This 'tidal locking' creates temperature gradients across each of the planets' surfaces, meaning that any of them could have water at their surface under the right atmospheric conditions.

But climate models suggest that the inner three planets of the system 1b, 1c and 1d are likely too hot to have water at anything but a small fraction of their surface.

The system's outermost planet, 1h, is expected to be a cold, icy world.

An artist's conception showing what the Trappist-1 planetary system may look like based on data about their diameters, masses and distances from the host star. The planets are labelled 1b-1h and each could have water on its surface given the right atmospheric conditions, meaning that all could potentially host alien life

Comparing the Trappist-1 system with the solar system. The left image compares the sizes of the main objects of the solar system with the planets of Trappist-1. The Trappist-1 star is small, barely bigger than Jupiter. The planets of Trappist-1 are comparable to Earth. The right image shows the amount of energy received from the star (vertical axis), which for Earth = 1. Numbers indicate how much flux (2 = twice more, ½ = half) a certain distance corresponds. Sizes of the planets are relative

But planets 1e, 1f, and 1g orbit within what the researchers call the star's 'habitable zone' and offer a holy grail to astronomers looking for life outside of the solar system.

'Depending on the local geological and atmospheric conditions, all of the planets have the potential to have liquid water,' co-author of the study Dr Amaury Triaud, an astronomer at Cambridge University, told MailOnline.

'On three of them, 1e, 1f and 1g, there is the potential for substantial amounts.'

Dr Triaud suspects that 1f is the most likely of the seven planets to host alien life.

'Planet F is a similar size to Earth but is a bit cooler, and the temperature is about right,' he said.

HOW WERE THE PLANETS FOUND? Artist's impression of a Trappist-1 star transit. The telescopes made readings as each planet transited the system's star, passing in front of it and causing its brightness to dip Each planet, labelled 1b-1h, was found via telescopes using the 'tranit' method, in which the orbit and other properties of planets is measured as they pass in front of their star, causing it to briefly dim. An international group of researchers used a series of space and ground telescopes to find the seven planets in the Trappist-1 system, which sits 39 light years away from Earth. Thousands of exoplanets have been discovered before, but this system has more Earth-sized planets orbiting its star than any planetary system seen before. The researchers measured the 'transits' of planets by reading dips in the star's brightness with each passing planet. They could then make estimates about the features of each planet based on their orbits and the time taken for each transit. Using these transits they discovered seven planets whose orbit is close enough to to the Trappist-1 star that they could have water at their surface. The astronomers plan to use larger telescopes to take readings of the planets' atmospheres in future to determine if they host alien life. Advertisement

'The planet is very similar to Earth in size, and it receives just a little less energy from its star than Earth does.

'Because the planets are likely 'tidally locked' they have a permanent dayside and a permanent nightside.

'The day side being constantly in the stellar glare is likely hotter than the equilibrium temperature, likely making up for its cooler equilibrium temperature.'

'This is a bit of speculation, but ultimately what is important is that for the first time we have planets with properties that will allow us to verify these speculations, and that is the where all our excitement comes from.'

Planets 1e, 1f and 1g could harbour oceans of water on their surfaces making them a top target for future investigation.

The presence of life leaves unique chemical signals in the atmosphere which could possibly be detected on these nearby worlds using large telescopes.

View of the Trappist planetary system from above. The star is at the centre and the planets are in orbit around it. Their relative position corresponds to what the system would have looked like when the researchers saw the first planet pass in front of the star. The relative sizes of the planets are correct, but on a different scale to their distance to the star

Artist's concept of what Trappist-1 planet 1f could look like. 1f has been listed by the researchers as the most likely planet to host alien life. Dr Amaury Triaud told MailOnline: 'Planet F is a similar size to Earth but is a bit cooler, and the temperature is about right. 'The planet is very similar to Earth in size, and it receives just a little less energy from its star than Earth does'

COULD HUMANS LIVE ON TRAPPIST-1'S PLANETS? Nasa created a travel poster design for Trappist - 1e. At 39 light years away the Trappist-1 system is relatively close to Earth considering the grand scale of the Milky Way galaxy At 39 light years away the Trappist-1 system is relatively close to Earth considering the grand scale of the Milky Way galaxy they inhabit, which measures 100,000 light years across. But researchers suggest that the Trappist-1 system is too far to ever be reached by humans, at least with current technology. 'The chances for humans reaching the system at the moment are not very good,' study co-author Dr Amaury Triaud, an astronomer at Cambridge University, told MailOnline. 'Our technology is really far from even sending a robotic probe, and the feasibility of humans surviving long term space travel is completely unknown. 'Unless we find a new physical process to harness energy I don’t see us colonising these planets in our lifetime, but then maybe someone will be inspired by the system and discover the means to go there, who knows!' Fellow astronomer Professor Ignas Snellen of the Netherlands's Leiden University, not involved in the study, agrees. 'Although the star is relatively nearby that is still very very far for humans to travel,' he told MailOnline. 'It would take hundreds of thousands of years to get there, maybe more.' Advertisement

And telescopes could also detect the presence of water oceans on 1e, 1f and 1g.

With the planets' Earth-like qualities, questions have been raised as to whether humans could one day colonise the system.

At 39 light years away, the Trappist-1 system is relatively close to Earth considering the grand scale of the Milky Way galaxy they share, measuring 100,000 light years across.

But researchers suggest that the system is too far to ever be reached by humans, at least with current technology.

'The chances for humans reaching the system at the moment are not very good,' Dr Triaud told MailOnline.

Some of the readings that the researchers took of stellar light dimming are shown here. The readings were taken by Nasa's Spitzer Space Telescope during the three weeks it monitored the new system. Each white dot represents a reading taken by the telescope, with vertical lines showing drops in light intensity as planets transited the star

Planet orbits were calculated using the Nasa telescope's readings shown here. Longer vertical drops in stellar light intensity represent a larger planet blocking out more starlight. The time taken between two drops of similar intensity told the researchers what a planet's orbit was. Short gaps in the readings are periods where the telescope transmitted data to Earth

'Our technology is really far from even sending a robotic probe, and the feasibility of humans surviving long term space travel is completely unknown.

'Unless we find a new physical process to harness energy I don’t see us colonising these planets in our lifetime, but then maybe someone will be inspired by the system and discover the means to go there, who knows!'

Fellow astronomer Professor Ignas Snellen of the Netherlands's Leiden University, not involved in the study, agrees.

'Although the star is relatively nearby that is still very very far for humans to travel,' he told MailOnline.

'It would take hundreds of thousands of years to get there, maybe more.'

The international team of astronomers who made the discovery first found three of the Earth-like worlds orbiting the Trappist-1 star last year.

The astronomers used a series of both ground-based and space telescopes to find the new planets. They measured the dimming of light of the system's star Trappist-1 as each planet orbited in front of it. This image shows the Nasa Spitzer Space Telescope used by the team, which takes stellar light readings from Earth's orbit

This ground-based telescope located on the island of La Palma, Spain, was another telescope used by the team in their study. The telescope is owned by Liverpool John Moores University and was one of a series of ground telescopes from across the globe used, including observatories in Chile, South Africa and Hawaii

But their latest discovery, which found four new planets orbiting the star, means the system has the highest number of Earth-like planets ever discovered in a planetary system outside of our own.

And the new system's discovery sheds new light on the number of Earth-like planets that could occupy the Milky Way.

'It is hard to know if this is one of many or if we were lucky, but 30-50 per cent of these ultracool dwarf stars could have planets like these,' Dr Triaud said.

'Because these stars represent the majority of the stars in the Milky Way, this means that there could be a lot of Earth-like planets in our galaxy.

The sun and the ultracool dwarf star Trappist-1 are shown to scale here. The faint star has only 11 per cent of the diameter of the sun and is much redder in colour. Even though the Trappist-1 star is small, because its planets orbit tightly six of them have surface temperatures between 0-100°C (32-212°F), a vital component for alien life

This chart shows the naked-eye stars visible on a clear dark night in the sprawling constellation of Aquarius, where the new star system is located. The position of the faint and red ultracool dwarf star Trappist-1 is marked. Although it is relatively close to the sun, it is faint and not visible in small telescopes

'Before we just had an idea of where to look for life, but now we have a target.'

Trappist-1 is a 'supercool' dwarf star, much smaller and dimmer than the sun at around 80 times the mass of Jupiter.

Trappist-1 is much cooler and redder than the sun and lies in the constellation of Aquarius.

Such stars are both common in the Milky Way and are long-lived, but planets are rarely found around them.

An artist’s impression of an imagined view from close to one of the seven planets orbiting Trappist-1. The next step for the researchers is to search each of the planets' atmospheres to check for signs of life, such as carbon dioxide, oxygen, methane, and hydrogen. A combination of these elements provide the ideal cocktail for biological life to grow

HOW MIGHT HUMANS EXPLORE THE NEW PLANETS? Solar sails use the radiation of stars to propel spacecraft forward without conventional fuel. An artist's impression of solar sails is shown here Engineers have been developing new space travel technologies to reach exoplanets outside of the solar system for a decade. Travel between star systems is difficult because storing enough conventional fuel to travel interstellar distances without heavily weighing down the spacecraft is near impossible. To travel light years in a lifetime would require spacecraft that can travel far faster than current technology allows. But some scientists have proposed new methods of transport that do not use conventional rocket fuel. A soap-sized probe was developed earlier this month that uses photon sails driven by radiation from stars to propel it through space at 14million metres per second (46million feet per second). The probe weighs 100 grams (0.2lbs) and measures only a few inches. It was designed to investigate nearby exoplanet Proxima b located around four light years from Earth. But whether this model could ever scale up to carry humans is debatable. Another option put forward by researchers is to use nuclear detonations in space to propel a spacecraft forward on the shock waves at rapid speeds. 'Nuclear Pulse Propulsion' would not involve detonating nuclear weapons on the spacecraft - a long ship would be fitted with a larger pusher plate. Weapons could be detonated a safe distance behind the craft so that the pusher plate could catch the shock wave. Advertisement

Despite being so close to the Earth, this star is too dim and too red to be seen with the naked eye or even visually with a large amateur telescope.

The team used a modest 60cm telescope called Trappist (the Transisting Planets and Planetesimals Small Telescope) based in Chile, to find the planets.

Small stars such as Trappist-1 are good for these observations because a large part of their small surface is blocked when planets pass over it.

An artist's impression of what the surface of one of the new planets may look like. The research team emphasise that further observations are needed to confirm the true nature of each of the planets, as their observations so far have been educated guesses based on the planets' orbits, radii and mass

After their initial Trappist-1 discovery in 2016, the international team spent months scanning the system for transits using several telescopes from around the world.

The team observed 34 clear transits, allowing them to identify four additional planets orbiting Trappist-1, taking the total to seven.

Gillon and colleagues emphasise that additional observations are required to thoroughly characterise these planets, particularly the seventh, outermost planet whose orbital period and interaction with the inner planets remains unknown.

The James Webb Space Telescope, among many other global telescopes, will now search the planets' atmospheres for molecular signs of life.