Scientists have discovered 18 Earth-sized planets beyond the solar system, including one of the smallest known so far and another that could offer conditions friendly to life.

The exoplanets are so small that previous surveys had overlooked them, said researchers at the Max Planck Institute for Solar System Research (MPS) in Germany.

The study, published in the journal Astronomy & Astrophysics, re-analysed a part of the data from NASA’s Kepler Space Telescope with a new and more sensitive method that they developed.

The team estimates that the new method has the potential of finding more than 100 additional exoplanets in the Kepler mission’s entire data set.

Somewhat more than 4,000 planets orbiting stars outside our solar system are known so far.

Of these so-called exoplanets, about 96 per cent are significantly larger than our Earth, most of them more comparable with the dimensions of the gas giants Neptune or Jupiter.

This percentage likely does not reflect the real conditions in space, however, since small planets are much harder to track down than big ones.

Moreover, small worlds are fascinating targets in the search for Earth-like, potentially habitable planets outside the solar system.

The 18 newly discovered worlds fall into the category of Earth-sized planets.

The smallest of them is only 69 per cent of the size of the Earth; the largest is barely more than twice the Earth’s radius.

Common search algorithms were not sensitive enough, researchers said.

In their search for distant worlds, scientists often use the so-called transit method to look for stars with periodically recurring drops in brightness.

If a star happens to have a planet whose orbital plane is aligned with the line of sight from Earth, the planet occults a small fraction of the stellar light as it passes in front of the star once per orbit.

Their effect on the stellar brightness is so small that it is extremely hard to distinguish from the natural brightness fluctuations of the star and from the noise that necessarily comes with any kind of observation.

The team, including Rene Heller from MPS, has now been able to show that the sensitivity of the transit method can be significantly improved, if a more realistic light curve is assumed in the search algorithm.

The new algorithm does not search for abrupt drops in brightness like previous standard algorithms, but for the characteristic, gradual dimming and recovery.

This makes the new transit search algorithm much more sensitive to small planets the size of the Earth.

“Our new algorithm helps to draw a more realistic picture of the exoplanet population in space,” said Michael Hippke of Sonneberg Observatory.

“This method constitutes a significant step forward, especially in the search for Earth-like planets,” Hippke said.

“In most of the planetary systems that we studied, the new planets are the smallest,” said Kai Rodenbeck of the University of Gottingen in Germany.

Most of the new planets orbit their star closer than their previously known planetary companions.

The surfaces of these new planets therefore likely have temperatures well in excess of 100 degrees Celsius; some even have temperatures of up to 1,000 degrees Celsius.

Only one of the bodies is an exception: it likely orbits its red dwarf star within the so-called habitable zone.

Also read: Oldest meteorite collection on Earth discovered in Chile

At this favourable distance from its star, this planet may offer conditions under which liquid water could occur on its surface — one of the basic prerequisites for life as we know it on Earth. </s> So far almost 4,000 planets have been discovered orbiting stars other than the Sun, and that tally is constantly growing. Now another 18 exoplanets have been added to the haul, but the difference this time is that all of them are roughly Earth-sized – much smaller than the Neptune-sized average found so far. The discovery was made in old data, using a new and more sensitive algorithm.

Since Earth is the only planet known (so far) to harbor life, worlds like our own are of particular interest to exoplanet-hunters. That makes this new haul pretty exciting, especially given that these planets are on the small side of the scale and are usually harder to find than Jupiter-sized gas giants.

The smallest of the bunch is only about two-thirds the size of Earth, making it the second-smallest exoplanet detected to date. Two others are also smaller than Earth, while the rest of the crop range up to about twice the size of our home world. The most exciting new planet though is one that appears to be cool enough to potentially host liquid water on its surface, meaning it could be habitable.

The 18 new exoplanets, to scale, as compared to Earth and Neptune. The green one, named EPIC 201238110.02, also appears to be cool enough to host liquid water on its surface NASA/JPL (Neptune), NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring (Earth), MPS/René Heller

These 18 new planets were discovered in old data by a team of German astronomers. Exoplanets are usually found using the transit method, which sounds simple enough in theory – essentially, telescopes like Kepler stare at stars and watch for sudden dips in their brightness. If that occurs on a regular schedule, it indicates that a planet is passing between the star and the telescope, blocking some of the light.

Obviously, larger planets make their presence known much more clearly, creating sharp drops in brightness. So it's no surprise that the majority of detected exoplanets are gas giants like Jupiter and Saturn, and ice giants like Uranus and Neptune.

"Standard search algorithms attempt to identify sudden drops in brightness," says René Heller, first author of two new studies. "In reality, however, a stellar disk appears slightly darker at the edge than in the center. When a planet moves in front of a star, it therefore initially blocks less starlight than at the mid-time of the transit. The maximum dimming of the star occurs in the center of the transit just before the star becomes gradually brighter again."

This graph compares the older algorithm for detecting exoplanets as they transit their host stars, against the new, more sensitive algorithm that can detect smaller worlds ASA/SDO (Sun), MPS/René Heller

So the team developed a new, more sensitive method. It works on the same basic principle but rather than just looking for the abrupt changes, it takes into account the more gradual dimming and brightening that occurs when smaller planets pass in front of a star. They may not be as immediately obvious, but if they repeat regularly they're still a solid indication of a planet's existence.

To test out the new method, the researchers applied it to an old batch of data gathered during Kepler's second run, between 2014 and 2018. During that time the telescope identified 517 stars with at least one planet around them, and the team re-analyzed this group to see if they could find any smaller worlds that were missed the first time around. Lo and behold, 18 such planets emerged from the data.

Of course, this is just the beginning. There's plenty more data from Kepler and its planet-hunting successor TESS to trawl through in search of hidden Earth-like worlds.

Two separate studies were published in the journal Astronomy & Astrophysics [1], [2].

Source: Max Planck Institute </s> A Grade 10 student from Regina has won two awards at the Canada-Wide Science Fair in Fredericton after he developed an algorithm to identify exoplanets from data too numerous to sift through manually.

Exoplanets are planets which orbit other stars outside of the solar system.

"They're really hard to find using traditional techniques and telescopes here on Earth," the student, Ali Rizvi, told CBC Radio's The Afternoon Edition on Thursday.

"So, NASA launched a telescope in 2009 called the Kepler telescope. They recorded measurements for millions of stars and observed light values."

Rizvi came up with the idea after reading about the Kepler telescope reaching the end of its lifecycle. Ali figured there are likely more exoplanets which have not yet been discovered.

He looked at the methods currently being used and tried to improve upon them by using artificial intelligence. He defined what an exoplanet should look like and what shouldn't be there in his algorithms using existing data and then once the artificial intelligence knew what to look for, the algorithms were applied to new data.

No new exoplanets have been found yet but the opportunity remains as the algorithms run — but only on weekends. Rizvi said he has had support from his family and teachers, with help coming from his father, who's an engineer.

Rizvi took home a gold medal of excellence and an award for excellence in astronomy. The wins are something he didn't expect.

"It was definitely surreal," he said. "It just felt amazing at the moment and I tried to remain calm as I walked up."

He's plans on refining and improve the project to find more exoplanets. If he finds one, he'll maybe name it after himself.

Rizvi plans on pursuing a career in computer science or computer engineering once he goes to university. </s> UPDATE: A mistake about an exoplanet's exact position has been corrected

Astronomers have found over 4,000 planets in other star systems, but almost all of these "exoplanets" are massive compared to Earth. In fact, 96% of them are larger than Earth. Mostly, astronomers have found gas giants like Neptune or Jupiter, but very few small planets. So the announcement this week that 18 exoplanets have been discovered that fall into the broad category of Earth-sized planets is big news.

The even bigger news is that one of them is slightly smaller than our planet. Have we just found Earth 2.0?

What do we know about this planet?

The candidate for an "Earth twin" is called EPIC 201497682.03. It resides around a red dwarf star called EPIC 201497682 that’s 831 light years from our solar system between the constellations Leo and Virgo. It’s 69% of the size of the Earth, the closest fit in the 18 exoplanets found by scientists at the Max Planck Institute for Solar System Research (MPS), the Georg August University of Göttingen, and the Sonneberg Observatory, whose results have been published in Astronomy & Astrophysics.

What about its host star?

"EPIC” stands for “Ecliptic Planet Input Catalog”, which was a list of targets that the Kepler Space Telescope's K2 mission was supposed to observe. However, EPIC 201497682 is also known in other star catalogs as UCAC4 453-051784, 2MASS J11154478+0029171, and Gaia DR2 3810098271767907840. "When we look at the star now we see the light that emerged from this system about 300 years before Christopher Columbus reached The Americas," said Dr. Rene Heller from MPS, first author of the paper. "It’s quite compelling that we were able to find a rock just slightly larger than Mars around this remote star."

Why are small exoplanets hard to find?

Small planets are harder to track down than big ones. Exoplanet-hunters find their targets by detecting a drop in brightness as a planet travels (transits) in front of its host star. However, while large planets cause sudden drops in brightness that is easy to detect, small planets cause such a tiny change in brightness that it's hard to separate it from the natural brightness fluctuations of the star. "Standard search algorithms attempt to identify sudden drops in brightness," said Heller. "In reality, however, a stellar disk appears slightly darker at the edge than in the center. When a planet moves in front of a star, it therefore initially blocks less starlight than at the mid-time of the transit. The maximum dimming of the star occurs in the center of the transit just before the star becomes gradually brighter again," he said.

How were these new exoplanets found?

As well as the "sub-Earth" planet EPIC 201497682.03, the scientists found 17 planets slightly larger than Earth, all of them found in data from the Kepler Space Telescope using a new search algorithm called transit least-squares (TLS). "Our new algorithm helps to draw a more realistic picture of the exoplanet population in space," summarises Michael Hippke of Sonneberg Observatory. The new algorithm looks for gradual darkening, not the abrupt brightness drops that algorithms usually look for. This makes the new transit search algorithm significantly more sensitive to very small planets the size of the Earth. "This method constitutes a significant step forward, especially in the search for Earth-like planets,” said Hippke.

What is the Kepler Space Telescope?

The researchers used data from NASA’s Kepler Space Telescope as a test bed for their new algorithm. In its first mission phase from 2009 to 2013, Kepler recorded the light curves of more than 100,000 stars, resulting in the discovery of over 2,300 planets. After a technical defect, the telescope had to be used in an alternative observing mode, called the K2 mission, but it still managed to monitor more than 100,000 more stars by the end of the mission in 2018. The researchers decided to re-analyze all 517 stars from K2 that were already known to host at least one transiting planet.

Could these exoplanets be habitable?

Most of them are probably too hot. Most of the new planets detected in the old data orbit their star closer than other known planets. The surfaces of these new planets therefore likely have temperatures well in excess of 100ºC/212ºF, while some have temperatures of up to 1,000ºC/1,832ºF. Only one, a planet called EPIC 201238110.02, resides in the "habitable zone". "It's 1.87 Earth diameter in size, so it’s rather a super-Earth than an Earth twin," says Heller. The host star EPIC 201238110 is 522 light years from us, also between the constellations Leo and Virgo.

Can the new algorithm be used to find another Earth 2.0?

Given their discovery rate of 3.5% new planets in old data, the researchers think that their method will help them to find more than 100 other Earth-sized worlds in the Kepler data. “This new method is also particularly useful to prepare for the upcoming PLATO mission to be launched in 2026 by the European Space Agency,” says Professor Dr. Laurent Gizon, managing director at the MPS.

What is the PLATO mission?

Planned for launch by 2026, the PLATO (PLAnetary Transits and Oscillations of stars) mission will assemble the first-ever catalog of confirmed planets, including planets in the habitable zone of their host stars. It will study hundreds of rocky, icy and giant planets and accurately measure their radii, masses, and ages. It’s expected to revolutionize astronomers’ understanding of planet formation and the evolution of planetary systems. "Does a second Earth exist in the Universe? is one of the exciting questions in astrophysics today," says Johann-Dietrich Wörner, director general of ESA. "With our PLATO satellite, we are focusing on Earth-like planets orbiting up to the habitable zone around other stars which are similar to our Sun. This will be a major step towards finding another Earth." </s> Scientists at the Max Planck Institute for Solar System Research (MPS), the Georg August University of Göttingen, and the Sonneberg Observatory have discovered 18 Earth-sized planets beyond the solar system. The worlds are so small that previous surveys had overlooked them. One of them is one of the smallest known so far; another one could offer conditions friendly to life. The researchers re-analyzed a part of the data from NASA's Kepler Space Telescope with a new and more sensitive method that they developed. The team estimates that their new method has the potential of finding more than 100 additional exoplanets in the Kepler mission's entire data set. The scientists describe their results in the journal Astronomy & Astrophysics.

Somewhat more than 4000 planets orbiting stars outside our solar system are known so far. Of these so-called exoplanets, about 96 percent are significantly larger than our Earth, most of them more comparable with the dimensions of the gas giants Neptune or Jupiter. This percentage likely does not reflect the real conditions in space, however, since small planets are much harder to track down than big ones. Moreover, small worlds are fascinating targets in the search for Earth-like, potentially habitable planets outside the solar system.

The 18 newly discovered worlds fall into the category of Earth-sized planets. The smallest of them is only 69 percent of the size of the Earth; the largest is barely more than twice the Earth's radius. And they have another thing in common: all 18 planets could not be detected in the data from the Kepler Space Telescope so far. Common search algorithms were not sensitive enough.

In their search for distant worlds, scientists often use the so-called transit method to look for stars with periodically recurring drops in brightness. If a star happens to have a planet whose orbital plane is aligned with the line of sight from Earth, the planet occults a small fraction of the stellar light as it passes in front of the star once per orbit.

"Standard search algorithms attempt to identify sudden drops in brightness," explains Dr. Rene Heller from MPS, first author of the current publications. "In reality, however, a stellar disk appears slightly darker at the edge than in the center. When a planet moves in front of a star, it therefore initially blocks less starlight than at the mid-time of the transit. The maximum dimming of the star occurs in the center of the transit just before the star becomes gradually brighter again," he explains.

Large planets tend to produce deep and clear brightness variations of their host stars so that the subtle center-to-limb brightness variation on the star hardly plays a role in their discovery. Small planets, however, present scientists with immense challenges. Their effect on the stellar brightness is so small that it is extremely hard to distinguish from the natural brightness fluctuations of the star and from the noise that necessarily comes with any kind of observation. René Heller's team has now been able to show that the sensitivity of the transit method can be significantly improved, if a more realistic light curve is assumed in the search algorithm.

"Our new algorithm helps to draw a more realistic picture of the exoplanet population in space," summarizes Michael Hippke of Sonneberg Observatory. "This method constitutes a significant step forward, especially in the search for Earth-like planets."

The researchers used data from NASA's Kepler space telescope as a test bed for their new algorithm. In the first mission phase from 2009 to 2013, Kepler recorded the light curves of more than 100,000 stars, resulting in the discovery of over 2300 planets. After a technical defect, the telescope had to be used in an alternative observing mode, called the K2 mission, but it nevertheless monitored more than another 100,000 stars by the end of the mission in 2018. As a first test sample for their new algorithm, the researchers decided to re-analyze all 517 stars from K2 that were already known to host at least one transiting planet.

In addition to the previously known planets, the researchers discovered 18 new objects that had previously been overlooked. "In most of the planetary systems that we studied, the new planets are the smallest," co-author Kai Rodenbeck of the University of Göttingen and MPS describes the results. What is more, most of the new planets orbit their star closer than their previously known planetary companions. The surfaces of these new planets therefore likely have temperatures well in excess of 100 degrees Celsius; some even have temperatures of up to 1000 degrees Celsius. Only one of the bodies is an exception: it likely orbits its red dwarf star within the so-called habitable zone. At this favorable distance from its star, this planet may offer conditions under which liquid water could occur on its surface—one of the basic prerequisites for life as we know it on Earth.

Of course, the researchers cannot rule out that their method, too, is blind to other planets in the systems they investigated. In particular, small planets at large distances to their host stars are known to be problematic. They require more time to complete a full orbit than planets orbiting their stars closer in. As a consequence, the transits of planets in wide orbits occur less often, which makes their signals even harder to detect.

The new method developed by Heller and his colleagues opens up fascinating possibilities. In addition to the 517 stars now being investigated, the Kepler mission also offers data sets for hundreds of thousands of other stars. The researchers assume that their method will enable them to find more than 100 other Earth-sized worlds in the data of the Kepler primary mission. "This new method is also particularly useful to prepare for the upcoming PLATO mission to be launched in 2026 by the European Space Agency," says Prof. Dr. Laurent Gizon, Managing Director at the MPS. PLATO will discover and characterize many more multi-planet systems around Sun-like stars, some of which will be capable of harboring life. </s> Of all the exoplanets, planets outside of Earth's solar system, discovered in recent years, one that's captured some of the most attention is Kepler-186f. It's often described as one of the "most Earth-like" of all exoplanets discovered and a new study just adds to the case.

A new look at Kepler-186f's axial tilt, also known as obliquity, is stable just like Earth's. Having a stable axial tilt means that the planet likely has both a stable climate and changing seasons. Getting a stable axial tilt as a planet is a complex endeavor, one that involves a planet's relationship with both its parent star, its sibling planets in its solar system, and even its moons. Axial tilt is crucial for a planet's success, to the extent that an unstable tilt might have led to Mars becoming inhospitable to life.

Researchers at Georgia Tech looked at the relationship between Earth and Mars to better understand Kepler-186f. Both planets interact with each other strongly, and as a result their axial tilts on their own could get wobbly. However, the Earth's moon keeps the Blue Planet in check, keeping the tilt steady. The Earth's moon is unique in the solar system, the only satellite to have such a stabilizing effect. 



Things play out with a degree of similarity in the Kepler system, where 186f interacts with the similarly named exoplanet Kepler-62f. Kepler-62f was seen as the most Earth-like exoplanet until 186f was discovered in 2014.

“It appears that both exoplanets are very different from Mars and the Earth because they have a weaker connection with their sibling planets. We don’t know whether they possess moons, but our calculations show that even without satellites, the spin axes of Kepler-186f and 62f would have remained constant over tens of millions of years.” says Gongjie Li, a professor who led the study, in a press statement. 



There's a lot scientists don't know about either planet. While 186f has a radius larger than Earth and it orbits its star every 130 days, scientists still don't know its mass, composition or density. We also have no idea if the planets have water on them, although they each make good candidates.

This latest study adds to that suggestion.

“Our study is among the first to investigate climate stability of exoplanets and adds to the growing understanding of these potentially habitable nearby worlds,” says.

“I don’t think we understand enough about the origin of life to rule out the possibility of their presence on planets with irregular seasons. Even on Earth, life is remarkably diverse and has shown incredible resilience in extraordinarily hostile environments. But a climatically stable planet might be a more comfortable place to start," says grad student Yutong Shan, who also worked on the study.

There has been a huge surge in exoplanet discoveryin recent years. In large part that's because of the namesake of these various planets, the Kepler Space Telescope. And now that its eventual replacement, TESS, has launched, it's only likely even more will be discovered in the future. </s> CLOSE NASA's Kepler spacecraft discovered more than 4,000 potential new planets outside our solar system, some of which are in the "habitable" zone of their star. USA TODAY

This artists’s conception gives an impression of how common planets are around the stars in the Milky Way. The planets, their orbits and their host stars are all vastly magnified compared to their real separations. (Photo: ESO/M. Kornmesser)

The universe just got a little more crowded.

Nearly 100 new exoplanets — planets outside of our solar system — have been discovered, scientists announced in a new study published Thursday.

Using powerful telescopes, exoplanets can be detected as they orbit around their star, which causes a subtle dimming of starlight.

These most recent exoplanets were spotted using NASA's Kepler space telescope, now in orbit around the Earth. Though the spacecraft had a major mechanical failure in 2013, scientists were able to reconfigure it to enable it to keep watching for exoplanets.

“We started out analyzing 275 candidates of which 149 were validated as real exoplanets," said study lead author Andrew Mayo, a PhD student at the Technical University of Denmark. "In turn, 95 of these planets have proved to be new discoveries.”

More: Distant Earth-like planets could harbor water — and maybe life

Since the first exoplanet was discovered in 1995, about 3,600 exoplanets have been found, ranging from rocky Earth-sized planets to large gas giants like Jupiter.

But this is only the tip of a very big iceberg: Astronomers say there are likely hundreds of billions of exoplanets in our galaxy alone.

“Exoplanets are a very exciting field of space science," Mayo said. "As more planets are discovered, astronomers will develop a much better picture of the nature of exoplanets which in turn will allow us to place our own solar system into a galactic context.”

The research was published Thursday in the Astronomical Journal.

Read or Share this story: https://usat.ly/2ocj7t0 </s> The universe just got a little more crowded.

Nearly 100 new exoplanets – planets outside our solar system – have been discovered, scientists announced in a new study published on Thursday.

Using powerful telescopes, exoplanets can be detected as they orbit around their star, which causes a subtle dimming of starlight.

These most recent exoplanets were spotted using Nasa’s Kepler space telescope, now in orbit around the Earth. Though the spacecraft had a major mechanical failure in 2013, scientists were able to reconfigure it to enable it to keep watching for exoplanets.

“We started out analysing 275 candidates of which 149 were validated as real exoplanets,” said study lead author Andrew Mayo, a PhD student at the Technical University of Denmark. “In turn, 95 of these planets have proved to be new discoveries.”

Scientists discover the first planets outside the Milky Way – and there may be trillions

Since the first exoplanet was discovered in 1995, about 3,600 exoplanets have been found, ranging from rocky Earth-sized planets to large gas giants like Jupiter.

But this is only the tip of a very big iceberg. Astronomers say there are likely hundreds of billions of exoplanets in our galaxy alone.

“Exoplanets are a very exciting field of space science,” Mayo said. “As more planets are discovered, astronomers will develop a much better picture of the nature of exoplanets which in turn will allow us to place our own solar system into a galactic context.”

Google’s computers help Nasa find two new planets around distant stars

The research was published on Thursday in the Astronomical Journal. </s> Scientists have discovered nearly 100 new 'exoplanets' in the search for Earth-like planets that could support life.

It's a major breakthrough that reveals new planets that range in size from smaller than Earth to celestial bodies even bigger than Jupiter.

The findings were made by a team of international colleagues from the University of Denmark, NASA, the University of Tokyo and others.

Researchers studied information from the K2 Kepler telescope mission, which aims to track down new exoplanets across the universe.

Exoplanets are planets found outside of our solar system, the Milky Way, that orbit a star – just like how Earth orbits the Sun.

To find these, scientists use a space telescope to track dips in light caused by the shadow of an exoplanet crossing in front of its host star.

Lead author Andrew Mayo, who works at the National Space Insititute, has presented the findings in the Astronomical Journal, and revealed that he had been working on the project since the first K2 data release back in 2014.

"We started out analysing 275 candidates of which 149 were validated as real exoplanets.

"In turn 95 of these planets have been proved to be new discoveries."

The original Kepler spacecraft launched back in 2009, questing for exoplanets in a small patch of sky.

But a mechanical failure crippled the telescope in 2013, paving the way for a follow-up K2 mission that's proving much more successful.

It allowed researchers to uncover a new field of exoplanets, raising hopes for the prospect of life beyond earth.

The goal is to eventually track down exoplanets that are rocky, habitable, Earth-sized planets that could be capable of supporting life.

"Exoplanets are a very exciting field of space science. As more planets are discovered, astronomers will develop a much better picture of the nature of exoplanets, which in turn will allow us to place our own solar system into a galactic context."

Mayo says they "detected planets that range from sub Earth-sized to the size of Jupiter and larger".

This story originally appeared in The Sun.
Eighteen Earth-like exoplanets are discovered via a new algorithm.