NASA/JPL-Caltech/T. Pyle

Kepler 186f ignited the imaginations of space nerds everywhere four years ago when NASA announced it as the first potentially habitable, Earth-size planet confirmed beyond our solar system. A new study indicates the exoplanet 500 light-years away may also have seasons and a climate similar to our own.

So far scientists believe they know Kepler 186f orbits in the so-called goldilocks zone around a dwarf star in the direction of the constellation Cygnus. That means temperatures are right for water to pool on the surface. The planet's size and mass also indicate it has a rocky surface like that of our planet.

Now, new research out of Georgia Tech University has analyzed the planet's spin and axial tilt and found that its tilt is stable like Earth's, which makes it likely Kepler 186f also has regular seasons and a stable climate.

This is no trivial thing when it comes to determining how friendly a planet might be to the development of life. As study co-author and Georgia Tech Assistant Professor Gongjie Li explains, large fluctuations in Mars' tilt could be part of why it dried up into the barren world it is today.

Over the eons, Mars has had an unstable tilt that varies by as much as 60 degrees. "That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water," Li said in a statement. The research was published in the The Astronomical Journal in May, but Georgia Tech shared more information on it this week.

The team says Kepler 62f, a slightly more distant but potentially habitable exoplanet, also has a stable tilt.

Earth's tilt is stabilized in part by other planets and our single large moon, something Mars lacks. It's not yet clear what's helping to keep the tilt of the two exoplanets steady, or if they even require any assistance.

"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," Li explains.

There's still not enough information to say for sure that either planet has liquid water or life, but as the years go on, both seem to become more worthy of a closer look.

Just when we'll get that follow-up glance is a bit up in the air at the moment. NASA's next-generation observatory, the James Webb Space Telescope, is running a few years behind schedule and its launch date keeps slipping. It's currently set to blast off in early 2021, so we may begin to get a better idea of what a sunset on Kepler 186f really looks like within five years.

University of Puerto Rico at Arecibo / PHL

Crowd Control: A crowdsourced science fiction novel written by CNET readers.

Solving for XX: The tech industry seeks to overcome outdated ideas about "women in tech."</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>The weather on exoplanets Kepler-186f and Kepler-62f may be a lot like what we're experiencing here on Earth, thanks to their stable axial tilt.

Earth-like exoplanets Kepler-186f and Kepler-62f are known for, well, their close similarity with our home planet. But a new study recently published in The Astronomical Journal disclosed that the two exoplanets, both orbiting within the habitable zone of their host stars, are actually more like Earth than we ever knew.

The research, conducted by scientists at the Georgia Institute of Technology (Georgia Tech) in Atlanta, examined the axial tilt of these two exoplanets and uncovered that it is very stable, just like Earth’s, Phys.org reports.

This discovery is a huge revelation in terms of these exoplanets’ likelihood of being habitable, because it points to a stable climate with regular seasons.

What We Know About Kepler-186f And Kepler-62f So Far

You may have heard about Kepler-186f (pictured above) a few years back, when it was first discovered in the data collected by NASA’s Kepler space telescope. Hailed as a massive breakthrough, Kepler-186f is the first confirmed Earth-sized planet to orbit a distant star in its habitable zone and is often referred to as “Earth’s cousin,” the Inquisitr previously reported.

Found in 2014, Kepler-186f is part of a five-planet star system located 500 light-years away from our planet, in the Cygnus constellation (the “Swan”), notes the Daily Mail. The exoplanet has a radius 10 percent larger than that of Earth and orbits its parent star — a red dwarf cooler than our sun, notes Space.com — every 130 days.

Of the five planets revolving around this distant red dwarf, Kepler-186f is the fifth and outermost, and scientists believe it’s most likely rocky.

Meanwhile, Kepler-62f resides even further away, in the Lyra constellation, at a distance of 1,200 light-years from us. Just like Kepler-186f, this exoplanet also belongs to a five-planet system and is the farthest one from its host star.

Discovered in 2013, Kepler-62f held the title of the most Earth-like exoplanet for about a year, until Kepler-186f was detected. This giant exoplanet is 40 percent larger than Earth and has a good chance of being a rocky world, possibly covered by oceans.

Both these exoplanets are found in the “Goldilocks zone,” or habitable region, of their respective stars, meaning that their distance from the parent star is just right for the surface temperature to allow the build-up of liquid water.

The recent study shows that, aside from all these traits, which make Kepler-186f and Kepler-62f good candidates for hosting life, the two Earth-like exoplanets also have an Earth-like climate.

This further increases the chances that alien life could evolve on these planets, study lead author Gongjie Li said in a Georgia Tech news release.

“Our study is among the first to investigate climate stability of exoplanets and adds to the growing understanding of these potentially habitable nearby worlds,” stated Li, who is an assistant professor of physics at the university.

Li’s team ran computer simulations to gauge the spin axis dynamics of both exoplanets and found out how much they tilt on their axes and how their tilt angles change over time.

Since axial tilt affects how much sunlight reaches a planet’s surface, these measurements are highly important in establishing what kind of climate we might expect to find on Kepler-186f and Kepler-62f.

According to the results, both exoplanets seem to have stable, Earth-like climates due to their stable axial tilt, which is very similar to that of our own planet.

Phys.org notes that Earth’s axial tilt has a mild oscillation once every 10,000 years and ranges between 22.1 and 24.5 degrees. Meanwhile, our planetary neighbor Mars has a “very unstable” axial tilt, which varies from zero to 60 degrees, Li points out.

“That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water,” said the physicist.

While Mars doesn’t have a large enough natural satellite to stabilize its axial tilt, our moon “keeps Earth’s variations in check,” preventing our planet’s axial tilt from oscillating too much under the influence of the strong interaction between Earth and Mars, notes Georgia Tech.

“It appears that both exoplanets are very different from Mars and the Earth because they have a weaker connection with their sibling planets,” says Li.

While there’s a possibility that life could also thrive on planets with irregular seasons, a stable climate could mean a better chance for alien life to spark on the two Earth-like exoplanets.

As Li puts it, “a climatically stable planet might be a more comfortable place to start.”</s>A new study from the Georgia Institute of Technology provides new clues indicating that an exoplanet 500 light-years away is much like Earth. Kepler-186f is the first identified Earth-sized planet outside the solar system orbiting a star in the habitable zone. This means it's the proper distance from its host star for liquid water to pool on the surface.

The Georgia Tech study used simulations to analyze and identify the exoplanet's spin axis dynamics. Those dynamics determine how much a planet tilts on its axis and how that tilt angle evolves over time. Axial tilt contributes to seasons and climate because it affects how sunlight strikes the planet's surface.

The researchers suggest that Kepler-186f's axial tilt is very stable, much like the Earth, making it likely that it has regular seasons and a stable climate. The Georgia Tech team thinks the same is true for Kepler-62f, a super-Earth-sized planet orbiting around a star about 1,200 light-years away from us.

How important is axial tilt for climate? Large variability in axial tilt could be a key reason why Mars transformed from a watery landscape billions of years ago to today's barren desert.

"Mars is in the habitable zone in our solar system, but its axial tilt has been very unstable—varying from zero to 60 degrees," said Georgia Tech Assistant Professor Gongjie Li, who led the study together with graduate student Yutong Shan from the Harvard-Smithsonian Center for Astrophysics. "That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water."

As a comparison, Earth's axial tilt oscillates more mildly—between 22.1 and 24.5 degrees, going from one extreme to the other every 10,000 or so years.

The orientation angle of a planet's orbit around its host star can be made to oscillate by gravitational interaction with other planets in the same system. If the orbit were to oscillate at the same speed as the precession of the planet's spin axis (akin to the circular motion exhibited by the rotation axis of a top or gyroscope), the spin axis would also wobble back and forth, sometimes dramatically.

Mars and Earth interact strongly with each other, as well as with Mercury and Venus. As a result, by themselves, their spin axes would precess with the same rate as the orbital oscillation, which may cause large variations in their axial tilt. Fortunately, the moon keeps Earth's variations in check. The moon increases our planet's spin axis precession rate and makes it differ from the orbital oscillation rate.

Mars, on the other hand, doesn't have a large enough satellite to stabilize its axial tilt. "It appears that both exoplanets are very different from Mars and the Earth because they have a weaker connection with their sibling planets," said Li, a faculty member in the School of Physics. "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."

Kepler-186f is less than 10 percent larger in radius than Earth, but its mass, composition and density remain a mystery. It orbits its host star every 130 days. According to NASA, the brightness of that star at high noon, while standing on 186f, would appear as bright as the sun just before sunset here on Earth. Kepler-186f is located in the constellation Cygnus as part of a five-planet star system.

Kepler-62f was the most Earth-like exoplanet until scientists noticed 186f in 2014. It's about 40 percent larger than our planet and is likely a terrestrial or ocean-covered world. It's in the constellation Lyra and is the outermost planet among five exoplanets orbiting a single star.

That's not to say either exoplanet has water, let alone life. But both are relatively good candidates. "Our study is among the first to investigate climate stability of exoplanets and adds to the growing understanding of these potentially habitable nearby worlds," said Li.

"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," added Shan. "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."

The paper, "Obliquity Variations of Habitable Zone Planets Kepler 62-f and Kepler 186-f," is published online in The Astronomical Journal.

The Daily Galaxy via Georgia Institute of Technology

Image credit top of page: with thanks to atramateria.com

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"Stop Saying That Dinosaurs Went Extinct. They Didn't"</s>Kepler-186f is the first identified Earth-sized planet outside the solar system orbiting a star in the habitable zone. This means it's the proper distance from its host star for liquid water to pool on the surface.

The Georgia Tech study used simulations to analyze and identify the exoplanet's spin axis dynamics. Those dynamics determine how much a planet tilts on its axis and how that tilt angle evolves over time. Axial tilt contributes to seasons and climate because it affects how sunlight strikes the planet's surface.

The researchers suggest that Kepler-186f's axial tilt is very stable, much like the Earth, making it likely that it has regular seasons and a stable climate. The Georgia Tech team thinks the same is true for Kepler-62f, a super-Earth-sized planet orbiting around a star about 1,200 light-years away from us.

How important is axial tilt for climate? Large variability in axial tilt could be a key reason why Mars transformed from a watery landscape billions of years ago to today's barren desert.

"Mars is in the habitable zone in our solar system, but its axial tilt has been very unstable—varying from zero to 60 degrees," said Georgia Tech Assistant Professor Gongjie Li, who led the study together with graduate student Yutong Shan from the Harvard-Smithsonian Center for Astrophysics. "That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water."

As a comparison, Earth's axial tilt oscillates more mildly—between 22.1 and 24.5 degrees, going from one extreme to the other every 10,000 or so years.

The orientation angle of a planet's orbit around its host star can be made to oscillate by gravitational interaction with other planets in the same system. If the orbit were to oscillate at the same speed as the precession of the planet's spin axis (akin to the circular motion exhibited by the rotation axis of a top or gyroscope), the spin axis would also wobble back and forth, sometimes dramatically.

Mars and Earth interact strongly with each other, as well as with Mercury and Venus. As a result, by themselves, their spin axes would precess with the same rate as the orbital oscillation, which may cause large variations in their axial tilt. Fortunately, the moon keeps Earth's variations in check. The moon increases our planet's spin axis precession rate and makes it differ from the orbital oscillation rate. Mars, on the other hand, doesn't have a large enough satellite to stabilize its axial tilt. "It appears that both exoplanets are very different from Mars and the Earth because they have a weaker connection with their sibling planets," said Li, a faculty member in the School of Physics. "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."

Kepler-186f is less than 10 percent larger in radius than Earth, but its mass, composition and density remain a mystery. It orbits its host star every 130 days. According to NASA, the brightness of that star at high noon, while standing on 186f, would appear as bright as the sun just before sunset here on Earth. Kepler-186f is located in the constellation Cygnus as part of a five-planet star system.

Kepler-62f was the most Earth-like exoplanet until scientists noticed 186f in 2014. It's about 40 percent larger than our planet and is likely a terrestrial or ocean-covered world. It's in the constellation Lyra and is the outermost planet among five exoplanets orbiting a single star.

That's not to say either exoplanet has water, let alone life. But both are relatively good candidates.

"Our study is among the first to investigate climate stability of exoplanets and adds to the growing understanding of these potentially habitable nearby worlds," said Li.

"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," added Shan. "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."

The paper, "Obliquity Variations of Habitable Zone Planets Kepler 62-f and Kepler 186-f," is published online in The Astronomical Journal.

Explore further: Orbital variations can trigger 'snowball' states in habitable zones around sunlike stars

More information: Yutong Shan et al. Obliquity Variations of Habitable Zone Planets Kepler-62f and Kepler-186f, The Astronomical Journal (2018). DOI: 10.3847/1538-3881/aabfd1</s>Earth is the only planet in the universe known to harbor life. Earth's orbital distance from the Sun ensures that it is not too hot, not too cold, and able to have liquid water on its surface. In other words, Earth lies within the Sun's habitable zone. We've discovered many exoplanets within the habitable zones of their respective stars, making them potentially habitable. But temperature isn't the only requirement for life. Mars, and Venus are also in the Sun's habitable zone, but are not lush living worlds. Part of the reason for that is the variation of seasons over time.

Seasons are caused by the tilt of a planet's rotational axis relative to its orbital plane, known as obliquity. Earth, for example, has an obliquity of about 23.5 degrees, while Mars has an obliquity of about 25 degrees. So both Earth and Mars experience similar seasons. But the axial tilt of Mars isn't stable over time. Over millions of years the Martian obliquity has varied from zero degrees to almost 60 degrees. This is because Mars interacts gravitationally with Earth and other planets in the inner solar system, and those little gravitational tugs cause the tilt of Mars to change over time. The same thing would happen to Earth were it not for the Moon. The gravitational tug of the Moon on Earth helps keep its obliquity stable, so it only varies between 22 degrees to 25 degrees. Earth has had pretty stable seasons over millions of years, while the instability of the Martian seasons has caused much of its surface water to evaporate, leaving it baren and dry.

For exoplanets, a similar effect could occur. Planets in the habitable zone would likely experience gravitational tugs from sibling planets, and that could make their seasons unstable. If a planet needs a large moon to keep its seasons stable, then life is probably very, very rare. Earth has the largest moon in the solar system, relative to its size, and most exoplanets wouldn't have such a companion. But a recent study has shown that exoplanets don't need a large moon to have stable seasons.

Using computer simulations, a team analyzed the motion of two exoplanets, Kepler-62f and Kepler-186f. These exoplanets are a bit more massive than Earth, and each orbit in their star's habitable zone. Both systems also have at least five exoplanets, similar to the inner solar system. They assumed the rotation of these planets was similar to Earth (about a day), and calculated how the gravitational tugs of their siblings affected axial tilt. They found that the obliquity of the planets could remain fairly stable over millions of years, and that would mean stable or slowly changing seasons. This held true even if the exoplanets don't have a large moon.

This doesn't mean that either exoplanet has life, but it does show that planets don't need a large moon to have stable seasons. And that means the possibility of extraterrestrial life is a bit better than we feared.

1: Shan, Yutong, and Gongjie Li. "Obliquity Variations of Habitable Zone Planets Kepler-62f and Kepler-186f." The Astronomical Journal 155.6 (2018): 237.</s>Thousands of alien worlds have been identified in the last few years. Many of these worlds also seem to be the right size, shape and even the right chemical composition. These exoplanets and exomoons are not only suitable for humans, but might actually be better than Earth.

This is where Project Blue comes into play. It is a planned mission that aims to take photographs of the nearest potentially habitable planet from Earth in the Alpha Centauri star system. The mission is calling this the search for "Earth 2.0" – a sister planet where life can survive and flourish.

So far not even one of the 3,730 exoplanets have actually been photographed, they have only been detected. In fact, there is so much information about exoplanets now that scientists are actually able to ascertain not just how far away a planet is from its host star, they are also able to find out the makeup of the planet, the elements in its atmosphere, and even its axial tilt.

Recent findings suggest that a planet's axial tilt is as important as its proximity to its star. Even planets that are in the Goldilocks Zone—where it is neither not too hot nor too cold for liquid water to exist on the surface.

One such planet that is possibly the best match for life, but much further away than the Alpha Centauri system is Kepler-186f. The new finding makes this planet almost perfect for human life.

Using the available information, astronomers made simulations to study the planet's spin axis dynamics- these are metrics that determine just how much a planet tilts on its axis and how that tilt evolves over time. Axial tilt is important because it is responsible for the changing seasons by modifying how mu

Researchers say that Kepler-186f's axial tilt is stable, almost Earth-like. It is likely that it has regular seasonal changes as well as stable climate, along with all that likely water pooling up as seas and oceans on the surface. The research team thinks that the same can be said of Kepler-62f, a much larger, "super-Earth-sized planet" which is orbiting around a star that is about 1,200 light-years away from Earth.

As to why there is so much focus on axial tilt, lead author of the study- Professor Gongjie Li explained, "Mars is in the habitable zone in our solar system, but its axial tilt has been very unstable—varying from zero to 60 degrees."

"That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water."

In comparison, Earth's tilt is stable, between 22.1 and 24.5 degrees, every 10,000 years or so, it oscillates between those two points, reports Phys.org.

On the stability of the planets' axial tilt, Li said, "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."</s>Kepler is not in the lineup against the White Sox on Thursday, LaVelle E. Neal of the Star Tribune reports.

Kepler will get a day off after starting the previous seven games, during which he's gone just 3-for-23 with two RBI dating back to June 20. In his absence, Taylor Motter will draw the assignment in right field while Jake Cave starts in center.</s>There are apparently two exoplanets out there that are not only in the habitable zone of stars, but also seem to have regular seasons and stable climates. Buzz60
A NASA study finds exoplanets Kepler-186f and Kepler-62f have stable axial tilts to allow for moderate seasons, making it more likely that the planets are habitable.