Two years ago, scientists detected a super-flare from the Sun’s neighboring star Proxima Centauri. The Red Dwarf, located some 4.25 light years away from our planet, sits at the bottom on the scale of stars, but the eruption baffled scientists, hinting that similar flares may have wiped out life on Earth’s closest exoplanet, if it had any.

Proxima Centauri is believed to host at least one Earth-sized rocky planet, dubbed Proxima b, in the habitable zone — the region where a planet is far enough from its star to have liquid water and bolsters the chances of finding life. But, the thing is even if Proxima b had any life, it might have been destroyed by the occurrence of intense flares, Allison Youngblood, a postdoctoral fellow at NASA's Goddard Space Flight Center, and her team estimated.

The solar flare detected back in 2016 was 10 times larger than previous ones and one of the strongest ever detected from a star this size. It unleashed 316,227 petawatts of energy and grew in brightness by a whopping factor of 68. At this level, even humans on Earth would have seen the faint star shining in the night sky, Popular Mechanics reported.

Using those observations and sophisticated modeling techniques, scientists predict at least five such flares erupt from the small star every year. This could mean serious trouble for Earth’s closest exoplanet and trim down the possibility of microbial life survival on its surface.

According to the astronomers, regular interactions between the flares and planetary atmosphere could drastically affect Proxima b's atmosphere. For a planet similar to Earth, flares of such magnitude would weaken the ozone layer progressively and deplete it by a whopping 90 percent in a matter of five years. And if this goes on for a few hundred thousand years, the ozone layer would be removed completely, leaving the planet unprotected from its star's harmful ultraviolet radiation.

"Then, if another one of these superflares comes along and there is no ozone protection, the UV radiation incident on the planet's surface would kill even the most radiation-resistant organisms," Youngblood said in a journal article preprint.

With that, the astronomers also note that if the atmosphere of the planet survives superflare impacts in the long-run, microscopic organisms will have to undergo complex adaptations to survive on the planet, just like how lichens evolved for extreme environments with features like UV-protecting pigments, ArsTechnica reported. Scientists around the world are working to better understand the impact of stellar flares in distant systems and how they could affect the possibility of life.

The ArXiv.org preprint paper titled “The first naked-eye superflare detected from Proxima Centauri” was made available on April 5 and is set to be published in the AAS Journals. </s> We've observed an alien world orbiting Barnard's Star, a tiny red dwarf that's only six light-years away, making it the second-closest known exoplanet beyond our solar system. Known as a "super-Earth," the planet (designated Barnard's Star b, or GJ 699 b) is thought to be at least 3.3 times the mass of Earth and orbits its star once every 233 days.

Barnard's Star is the fourth-closest star to our sun. Alpha Centauri's triple-star system (including Alpha Centauri A and B, plus Proxima Centauri) are the only stars nearer. Proxima Centauri is the closest star to have a known exoplanet in orbit, Proxima Centauri b. That world is slightly more massive than Earth, is located only 4.2 light-years away and has been pelted by solar flares, dashing hopes of it hosting life.

While an exciting (and historic) find, you can forget about Barnard's Star b bearing any resemblance to our planet. Barnard's Star is a very low mass and dim red dwarf that produces only 0.4 percent of the radiant power our sun generates. That means its "habitable zone" is extremely compact, and the exoplanet orbits beyond the star's "snow line." The snow line around any star is the distance beyond which water cannot exist in a liquid state on a planet's surface. The exoplanet has a predicted surface temperature of -170 degrees Celsius (-274 F), making it wholly incompatible for life (as we know it, anyway).

Still, this new exoplanetary discovery is exciting. Super-Earths are like nothing we have in our solar system and have only been discovered orbiting other stars more distant than Barnard's Star. These alien worlds occupy the mass range between the small rocky planets (like Earth, Mars and Venus) and the larger gaseous planets (like Neptune). Knowing that we have one of these strange exoplanets so nearby could allow us to get to know this planetary species a little better.

Although it's on our interstellar doorstep, discovering the Barnard's Star super-Earth took an international team of astronomers using decades of spectroscopic data of the star to find it.

"For the analysis we used observations from seven different instruments, spanning 20 years, making this one of the largest and most extensive datasets ever used for precise radial velocity studies," said Ignasi Ribas, of the Institut de Ciènces de l'Espai (ICE, CSIC), Spain, in a statement. Ribas is the first author of the study published in the journal Nature.

The radial velocity method used in exoplanet hunting requires precise observations of a star's spectrum. When starlight is received by telescopes, its spectrum can be split into its component wavelengths — such as infrared, visible and ultraviolet. However, if astronomers record observations of this starlight over many years, they may notice slight periodic frequency shifts. This is how we find exoplanets actually: As they orbit their host stars, their gravity causes their stars to wobble, pulling them toward and away from the telescope on Earth, creating a frequency shift that corresponds to the exoplanet's mass orbital period. Unlike NASA's Kepler and new Transiting Exoplanet Survey Satellite (TESS) – which both detect the slight dimming of starlight as an exoplanet orbits in front of its host star (known as a "transit") – the radial velocity method doesn't depend on detecting this dip in light to realize the presence of exoplanets around stars.

"This technique has been used to find hundreds of planets," said collaborator Paul Butler, of Carnegie Institution for Science and one of the pioneers of the radial velocity method, in a statement, "We now have decades of archival data at our disposal. The precision of new measurements continues to improve, opening the doors to new parameters of space, such as super-Earth planets in cool orbits like Barnard's Star b."

Since this exoplanet is so close, astronomers hope that they will be able to use it as a target for the next generation of space telescopes, such as the planned NASA Wide Field Infrared Survey Telescope (WFIRST). This makes Barnard's Star b a prime candidate for us to use powerful spectroscopic techniques to, one day, peer into its atmosphere (if it has one) and understand what it's really made of. </s> Amid much excitement in 2016, astronomers revealed the discovery of an Earth-sized planet around Proxima Centauri, the star closest to our Sun. This exoplanet, just 4.2 light years from Earth, was close enough to its red dwarf star that water might well exist on its surface.

Alas, now we know that life probably does not live on the planet, at least not on the surface. In March 2016, astronomers using an array of telescopes known as Evryscope observed a "superflare" 10 times larger than any previous one detected from the red dwarf star. Based on these observations and those of other instruments with spectrographs, the astronomers determined that about five of these superflares occur in a given year.

In an unpublished paper that describes their use of a model for interactions between the flares and a planetary atmosphere, the astronomers suggest such extreme solar activity would reduce the ozone of an Earth-like atmosphere by 90 percent within just five years, with complete depletion occurring within a few hundred thousand years. This means that ultraviolet light observed in the recent superflare reached the surface with 100 times the intensity needed to kill even microbic life that is resistant to UV light.

"Recent results have suggested that some more complex life such as lichens evolved for extreme environments and with adaptations such as UV-screening pigments may survive these radiation levels," the astronomers write in a journal article preprint. "This suggests that life on Proxima b will have to undergo complex adaptations to survive, even if the planetary atmosphere survives the long-term impact of the stellar activity."

That's too bad, because Proxima b has some intriguing characteristics. The planet is probably rocky, rather than a gas giant, and it's tidally locked to its star, meaning one side is always sunny while the other is perpetually gloomy. Therefore, if the planet does have an atmosphere, the surface temperature may vary from +30 degrees Celsius on the light side to -30 degrees Celsius on the dark side. These conditions would allow water, if the planet has any, to exist on the surface of the world as a liquid at some locations.

The arXiv. Abstract number: 1804.02001 (About the arXiv). Submitted to AAS Journals. </s> In the two years since astronomers confirmed the existence of an Earth-like planet just outside the Solar System, scientists have scrambled to determine Proxima b’s habitability.

Unfortunately, multiple studies proved disheartening, often indicating that the orb’s sun experiences too much flare activity to sustain an atmosphere or liquid water on its surface.

New NASA-led research, however, suggests Proxima b—which orbits red dwarf Proxima Centauri, the closest known star to our galaxy—could have enough water to support life.

Don’t get too excited about meeting the intergalactic neighbors just yet, though.

As indicated by those earlier studies, there is a lot working against aliens’ favor on Proxima b, which is just 1.3 times the mass of Earth.

While the planet looks good on paper, its history remains unclear: It probably experienced a runaway greenhouse effect (ultimately boiling away any oceans), and would have been pelted with intense radiation (X-ray and extreme ultraviolet fluxes) and solar wind.

It could also be home to an entirely new category of being.

“First and foremost, we don’t know whether Prox b even has an atmosphere and if it does, whether it has any water. Without those, life as we know it cannot exist,” study co-author Anthony Del Genio, of NASA’s Goddard Institute for Space Studies, told Universe Today.

“It could be [that] Prox b formed initially with no atmosphere, or that it formed with an atmosphere but in a stellar system that was water-poor,” he continued. “Or it could have formed with a modest atmosphere and lots of water. Or it could have formed with a very thick atmosphere. We just don’t know yet.”

The research—conducted by Del Genio and colleagues at the NASA Goddard Space Flight Center, Columbia University, and IT firm Trinnovim LLC—was published in the journal Astrobiology.

There are any number of reasons to assume no one lives on Proxima b, including the fact that M stars like Proxima Centauri tend to be too small, cool, bright, and active to sustain a habitable climate.

But that’s no reason to give up on the hunt.

Using a little imagination and a lot of high-tech software, Del Genio & Co. conceptualized Proxima b as having an atmosphere and water, in an effort to understand how those factors might produce habitable conditions* at the surface.

*Defined as: warm enough to sustain liquid water, but not so hot as to evaporate it all.

The team modeled a range of potential atmospheres, including ones like Earth (dominated by nitrogen with small amounts of CO2) and Mars (pure CO2).

According to Universe Today, they also considered things like whether its atmosphere would be thinner or thicker than ours, its oceans more or less salty, and whether the sea covers the entire planet.

In every case the scientists could dream up, Proxima b had at least some surface liquid water, giving it a “pretty good chance” of being habitable, Del Genio said.

“We also found that the ocean currents carried warm water from the dayside to the nightside, keeping parts of the nightside habitable even though they never see any light,” he added. “And if the ocean is very salty, almost the entire planet could be covered by liquid, but with temperatures below the usual freezing point almost everywhere.”

NASA’s planet hunter TESS (Transiting Exoplanet Survey Satellite), meanwhile, has begun providing data on planets beyond our Solar System.

The study of exoplanets has seen remarkable discoveries in the past decade, including a series of orbs that could host alien life. But some folks still want more. Read all about outer space here.

Let us know what you like about Geek by taking our survey. </s> For most of human history, people wondered if there were other planets out there in the unfathomable reaches of space. It turns out there are some very close to Earth, though. A team of astronomers has revived interest in Barnard’s Star, which hangs in space just six light years away. After dismissing evidence for an exoplanet orbiting this star in the 1970s, the team now says there’s a very good chance Barnard’s Star does indeed host a super-Earth.

Barnard’s Star is a red dwarf and one of the closest stars to Earth. Only the Centauri system is closer, and we know there’s at least one exoplanet there. Astronomers announced the discovery of Proxima Centauri b with great fanfare in 2016. At just 4.4 light years away, this planet will make an excellent target for future observation. The planet orbiting Barnard’s Star is just a little bit more distant, but it’s still close enough to be key to understanding exoplanets.

The tale of planet hunting around Barnard’s Star starts in the 1960s when astronomer Peter van de Kemp released compelling data supporting the existence of an exoplanet. However, other teams were unable to confirm, and by the 1970s we knew the discovery was merely a product of defective instruments. Scientists kept looking at the star, and now astronomers from the Institute of Space Studies of Catalonia and the Institute of Space Sciences in Spain have assembled 20 years of data to reveal Barnard’s Star b.

The newly published study lays out the basics of the exoplanet. Barnard’s Star b completes an orbit of the star every 233 Earth days. It’s about as far away from Barnard’s Star as Mercury is from Earth, but Barnard’s Star is much cooler. So, it’s distinctly outside the habitable zone with a surface temperature of -170 degrees Celsius (-274 degrees Fahrenheit). It’s the equivalent of a planet orbiting between Mars and Jupiter in our solar system. Barnard’s Star b has a mass about three times that of Earth, but we don’t know its size or composition yet. We suspect it’s rocky, though.

Barnard’s Star b does not transit in front of its host star from Earth’s perspective — that would have made detection vastly simpler. Instead, the team used the radial velocity method. They watched for small counter movements in the star that indicate a massive body (a planet) is in orbit. A smaller star like Barnard’s Star wobbles more than a more massive one, so even a small-ish planet like this one had some detectable effect.

The team claims high confidence that Barnard’s Star b is real, but other teams will need to confirm. We don’t want another van de Kemp scenario.

Now read: There’s an Earthlike planet orbiting our nearest neighbor, Proxima Centauri – but how might we actually get there?, Massive Solar Flares Diminish Chance of Finding Life on Proxima Centauri, and So Long, and Thanks for All the Planets: NASA Retires the Kepler Telescope </s> The study was co-led by researchers from Queen Mary University of London, and from the Institut d'Estudis Espacials de Catalunya and the Institute of Space Sciences/CSIC in Spain.

The potentially rocky planet, known as Barnard's star b, is a 'super-Earth' with a mass of at least 3.2 times that of the Earth, and it orbits around its host star once every 233 days.

The results, published in the journal Nature, show the planet lies at a distant region from the star known as the 'snow line'. This is well beyond the habitable zone in which liquid water, and possibly life, could exist.

The planet's surface temperature is estimated to be around -170 degrees Celsius meaning it is likely to be a frozen world which is uninviting to Earth-like life.

However, if the planet has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable.

Dr. Guillem Anglada Escudé, from Queen Mary's School of Physics and Astronomy, said: "Barnard's star is an infamous object among astronomers and exoplanet scientists, as it was one of the first stars where planets were initially claimed but later proven to be incorrect. Hopefully we got it right this time."

At nearly six light-years away Barnard's star is the next closest star to the Sun after the Alpha Centauri triple system.

It is a type of faint, low-mass star called a red dwarf. Red dwarfs are considered to be the best places to look for exoplanet candidates, which are planets outside our solar system.

Barnard's star b is the second closest known exoplanet to our Sun. The closest lies just over four light-years from Earth and was also discovered by a team led by Queen Mary's Dr. Anglada Escudé in 2016. That exoplanet, called Proxima b, orbits around the red dwarf star Proxima Centauri.

The researchers used the radial velocity method during the observations that led to the discovery of Barnard's star b. This technique detects wobbles in a star which are likely to be caused by the gravitational pull of an orbiting planet.

These wobbles affect the light coming from the star. As the star moves towards the Earth its spectrum appears slightly shifted towards the blue and, as it moves away, it is shifted towards the red.

This is the first time that this technique has been used to detect a planet this small so far away from its host star.

The researchers re-examined archive data obtained over a 20-year period, and added new observations with the latest generation of instruments, namely the CARMENES spectrometer in Spain, the ESO/HARPS instrument in Chile and the HARPS-N instrument in the Canary Islands.

This wealth of data provided the extraordinary accuracy needed to identify the influence of the planet with near certainty. The wobble observed in the star's motion corresponds to speeds of only just over 1 metre per second—about walking speed.

Dr. Ignasi Ribas, from Institut d'Estudis Espacials de Catalunya and the Institute of Space Sciences in Spain, said: "After a very careful analysis, we are over 99 per cent confident that the planet is there, since this is the model that best fits our observations. However, we must remain cautious and collect more data to nail the case in the future."

Further observations to increase the confidence of this result are already under way at various observatories, and the system is an excellent candidate for observation by the next generation of instruments specifically designed to image exoplanets directly, such as NASA's planned Wide Field Infra Red Survey Telescope (WFIRST).

If the planet can be observed directly it will provide vital information about its properties and extend our understanding of the kinds of planets that form around red dwarf stars.

An award-winning public engagement campaign, known as Pale Red Dot, allowed the public to follow in real time the observations and analysis that led to the discovery of Proxima b.

The public have also been able to follow the observations leading to this new discovery, a result of extending the search to other very nearby red dwarfs, via a similar web-based campaign known as the Red Dots project, @reddotsspace on Twitter).

The study includes contributions from Professor Richard Nelson and research student John Strachan, both members of Queen Mary's School of Physics and Astronomy.

This research was supported in part by the UK Science and Technology Facilities Council and a Queen Mary University of London Principal's Postgraduate Studentship.

Explore further: Assist astronomers' new hunt for Earth-like planets

More information: I. Ribas et al. A candidate super-Earth planet orbiting near the snow line of Barnard's star, Nature (2018). DOI: 10.1038/s41586-018-0677-y </s> The nearest single star to the sun apparently hosts a big, icy planet.

Astronomers have found strong evidence of a frigid alien world about 3.2 times more massive than Earth circling Barnard's Star, a dim red dwarf that lies just 6 light-years from the sun. Barnard's Star is our sun's nearest neighbor, apart from the three-star Alpha Centauri system, which is about 4.3 light-years away.

The newly detected world, known as Barnard's Star b, remains a planet candidate for now. But the researchers who spotted it are confident the alien planet will eventually be confirmed. [Barnard's Star b: What We Know About the "Super-Earth' Candidate]

"After a very careful analysis, we are 99 percent confident that the planet is there," Ignasi Ribas, of the Institute of Space Studies of Catalonia and the Institute of Space Sciences in Spain, said in a statement.

"However, we'll continue to observe this fast-moving star to exclude possible, but improbable, natural variations of the stellar brightness which could masquerade as a planet," added Ribas, the lead author of a new study announcing the detection of Barnard's Star b. That study was published online today (Nov. 14) in the journal Nature.

Barnard's Star b, if confirmed, will not be the nearest exoplanet to Earth. That designation is held by the roughly Earth-size world Proxima b, which orbits Proxima Centauri, one of the Alpha Centauri trio.

NASA's Kepler space telescope showed that small planets are common in the Milky Way galaxy at large. Together, Proxima b and Barnard's Star b strongly suggest that such worlds "are also common in our neighborhood," study co-author Johanna Teske, of the Department of Terrestrial Magnetism at the Carnegie Institution for Science in Washington, D.C., told Space.com. "And that is super-exciting."

Barnard's Star is named after the American astronomer E.E. Barnard, who in 1916 discovered the speediness Ribas mentioned. No other star moves faster across Earth's sky than Barnard's Star, which travels about the width of the full moon every 180 years. [Gallery: The Strangest Alien Planets]

This unparalleled apparent motion is a consequence of the proximity of Barnard's Star and its high (but not record-setting) velocity of 310,000 mph (500,000 km/h) relative to the sun.

And Barnard's Star is getting closer to us every day: In about 10,000 years, the red dwarf will take over the nearest-star mantle from the Alpha Centauri system. At that time, just 3.8 light-years will separate Barnard's Star from the sun.

Barnard's Star is about twice as old as Earth's sun, one-sixth as massive and just 3 percent as luminous. Because Barnard's Star is so dim, its "habitable zone" — the range of distances where liquid water may be possible on a world's surface — lies extremely close-in. Indeed, researchers estimate that zone to be a sliver that lies 0.06 AU to 0.10 AU from the star. (One AU, or astronomical unit, is the Earth-sun distance — about 93 million miles, or 150 million kilometers.)

The habitable-zone concept is a tricky one, of course. Gauging a world's true habitability requires a strong working knowledge of its atmospheric composition and thickness, among other characteristics. And such information is hard to come by for exoplanets.

Barnard's Star has long been a target of exoplanet hunters, but their searches have always come up empty — until now.

And the new detection wasn't easy: Ribas and his team analyzed huge amounts of data, both archival and newly gathered, before finally digging up Barnard's Star b.

They used the "radial velocity" method, which looks for changes in starlight caused by the gravitational tug of an orbiting planet. Such tugs cause a star to wobble slightly, shifting its light toward red wavelengths at times and toward the blue end of the spectrum at others, as seen from Earth. [7 Ways to Discovery Alien Planets]

"We used observations from seven different instruments, spanning 20 years of measurements, making this one of the largest and most extensive datasets ever used for precise radial-velocity studies," Ribas said in the same statement. "The combination of all data led to a total of 771 measurements — a huge amount of information!"

Never before had the radial velocity method been used to find such a small planet in such a distant orbit, study team members said. (Big, close-in planets tug their host stars more powerfully and therefore cause more dramatic, and more easily detectable, light shifts.)

Those seven instruments were the High Accuracy Radial Velocity Planet Searcher (HARPS), at the European Southern Observatory's (ESO) La Silla Observatory in Chile; the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope, at ESO's Paranal Observatory in Chile; HARPS-North, at the Galileo National Telescope in the Canary Islands; the High Resolution Echelle Spectrometer, at the Keck 10-meter telescope in Hawaii; the Carnegie Institute's Planet Finder Spectrograph, at the Magellan 6.5-m telescope at Las Campanas Observatory in Chile; the Automated Planet Finder at the 2.4-m telescope at the University of California's Lick Observatory; and& CARMENES, at the Calar Alto Observatory in Spain.

The researchers also detected hints of another possible planet in the system, orbiting farther out than Barnard's Star b — way farther out, with an orbital period of 6,600 Earth days. But this second signal is too weak to be deemed a planet candidate, Teske said.

"There's not enough data," she told Space.com.

Barnard's Star b is at least 3.2 times more massive than our own planet, making it a "super-Earth" — the class of worlds that are significantly larger than Earth but smaller than "ice giants" such as Neptune and Uranus.

The newfound planet candidate lies 0.4 AU from its host star and completes one orbit every 233 Earth days, according to the new study.

This orbital distance is similar to that of radiation-blasted Mercury in our own solar system. But, because Barnard's Star is so dim, the potential planet lies right around the system's "snow line" — the region where volatile materials such as water can condense into solid ices.

"Until now, only giant planets had been detected at such a distance from their stars," Rodrigo Diaz, of the Institute of Astronomy and Space Physics at the National Council of Scientific and Technical Research and the University of Buenos Aires in Argentina, said in an accompanying "News and Views" article that was also published today in Nature.

"The authors' discovery of a low-mass planet near the snow line places strong constraints on formation models for this type of planet," added Diaz, who was not involved in the new study.

Barnard's Star b, if it does indeed exist, is not a very promising abode for life as we know it, at least not on the surface. The potential planet is likely very cold, with an estimated surface temperature of about minus 275 degrees Fahrenheit (minus 170 degrees Fahrenheit), study team members said.

Confirmation of Barnard's Star b is unlikely to come from additional radial-velocity measurements, Diaz wrote. But super-precise measurements of star positions, such as those now being made by the European Space Agency's Gaia spacecraft, may do the job in the next few years, he added.

"Even more excitingly, the next generation of ground-based instrumentation, also coming into operation in the 2020s, should be able to directly image the reported planet, and measure its light spectrum," Diaz wrote.

"Using this spectrum, the characteristics of the planet’s atmosphere — such as its winds and rotation rate — could be inferred," he added. "This remarkable planet therefore gives us a key piece in the puzzle of planetary formation and evolution, and might be among the first low-mass exoplanets whose atmospheres are probed in detail."

WANT MORE STORIES ABOUT EXOPLANETS?
• Hottest exoplanet ever discovered has metallic skies, rain like lava
• Interstellar 'porch light' just might help us find space aliens </s> TEHRAN (Tasnim) – A planet has been discovered by astronomers in orbit around one of the closest stars to the sun, Barnard’s star.

The potentially rocky planet, known as Barnard’s star b, is a ‘super-Earth’ with a mass of at least 3.2 times that of the Earth, and it orbits around its host star once every 233 days.

The results, published in the journal Nature, show the planet lies at a distant region from the star known as the ‘snow line’. This is well beyond the habitable zone in which liquid water, and possibly life, could exist.

The planet’s surface temperature is estimated to be around -170 degrees Celsius meaning it is likely to be a frozen world which is uninviting to Earth-like life.

However, if the planet has a substantial atmosphere the temperature could be higher and conditions potentially more hospitable.

Dr. Guillem Anglada Escudé, from Queen Mary’s School of Physics and Astronomy, said: “Barnard’s star is an infamous object among astronomers and exoplanet scientists, as it was one of the first stars where planets were initially claimed but later proven to be incorrect. Hopefully we got it right this time.”

At nearly six light-years away Barnard’s star is the next closest star to the Sun after the Alpha Centauri triple system. </s> Step outside on a clear night, and you can be sure of something our ancestors could only imagine: Every star you see likely plays host to at least one planet.

The worlds orbiting other stars are called exoplanets, and they come in a wide variety of sizes, from gas giants larger than Jupiter to small, rocky planets about as big around as Earth or Mars. They can be hot enough to boil metal or locked in deep freeze. They can orbit their stars so tightly that a year lasts only a few days; they can orbit two suns at once. Some exoplanets are sunless rogues, wandering through the galaxy in permanent darkness.

That galaxy, the Milky Way, is the thick stream of stars that cuts across the sky on the darkest, clearest nights. Its spiraling expanse probably contains about 400 billion stars, our sun among them. And if each of those stars has not just one planet, but, like ours, a whole system of them, then the number of planets in the galaxy is truly astronomical: We’re already heading into the trillions.

We humans have been speculating about such possibilities for thousands of years, but ours is the first generation to know, with certainty, that exoplanets are really out there. In fact, way out there. Our nearest neighboring star, Proxima Centauri, was recently found to possess at least one planet – probably a rocky one. It’s 4.5 light-years away – more than 25 trillion miles (40 trillion km). The bulk of exoplanets found so far are hundreds or thousands of light-years away.

The bad news: As yet we have no way to reach them, and won’t be leaving footprints on them anytime soon. The good news: We can look in on them, take their temperatures, taste their atmospheres and, perhaps one day soon, detect signs of life that might be hidden in pixels of light captured from these dim, distant worlds.

The first exoplanet to burst upon the world stage was 51 Pegasi b, a hot Jupiter 50 light-years away that is locked in a four-day orbit around its star. The watershed year was 1995. All of a sudden, exoplanets were a thing.

When a planet passes directly between its star and an observer, it dims the star’s light by a measurable amount. Video via NASA/JPL-Caltech

But a few hints had already emerged. A planet now known as Tadmor was detected in 1988, though the discovery was withdrawn in 1992. Ten years later, more and better data showed definitively that it was really there after all.

And a system of three pulsar planets also had been detected, beginning in 1992. These planets orbit a pulsar some 2,300 light-years away. Pulsars are the high-density, rapidly spinning corpses of dead stars, raking any planets in orbit around them with searing lances of radiation.

Now we live in a universe of exoplanets. The count of confirmed planets is 3,700, and rising. That’s from only a small sampling of the galaxy as a whole. The count could rise to the tens of thousands within a decade, as we increase the number, and observing power, of robotic telescopes lofted into space.

How did we get here?

We’re standing on a precipice of scientific history. The era of early exploration, and the first confirmed exoplanet detections, is giving way to the next phase: sharper and more sophisticated telescopes, in space and on the ground. They will go broad but also drill down. Some will be tasked with taking an ever more precise population census of these far-off worlds, nailing down their many sizes and types. Others will make a closer inspection of individual planets, their atmospheres, and their potential to harbor some form of life.

Direct imaging of exoplanets – that is, actual pictures – will play an increasingly larger role, though we’ve arrived at our present state of knowledge mostly through indirect means. The two main methods rely on wobbles and shadows. The wobble method, called radial velocity, watches for the telltale jitters of stars as they are pulled back and forth by the gravitational tugs of an orbiting planet. The size of the wobble reveals the weight, or mass, of the planet.

This method produced the very first confirmed exoplanet detections, including 51 Peg b in 1995, discovered by astronomers Michel Mayor and Didier Queloz. Ground telescopes using the radial velocity method have discovered nearly 700 planets so far.

But the vast majority of exoplanets have been found by searching for shadows: the incredibly tiny dip in the light from a star when a planet crosses its face. Astronomers call this crossing a transit.

The size of the dip in starlight reveals how big around the transiting planet is. Unsurprisingly, this search for planetary shadows is known as the transit method.

NASA’s Kepler space telescope, launched in 2009, has found nearly 2,700 confirmed exoplanets this way. Now in its K2 mission, Kepler is still discovering new planets, though its fuel is expected to run out soon.

Each method has its pluses and minuses. Wobble detections provide the mass of the planet, but give no information about the planet’s girth, or diameter. Transit detections reveal the diameter but not the mass.

But when multiple methods are used together, we can learn the vital statistics of whole planetary systems – without ever directly imaging the planets themselves. The best example so far is the TRAPPIST-1 system about 40 light-years away, where seven roughly Earth-sized planets orbit a small, red star.

The TRAPPIST-1 planets have been examined with ground and space telescopes. The space-based studies revealed not only their diameters, but the subtle gravitational influence these seven closely packed planets have upon each other; from this, scientists determined each planet’s mass.

So now we know their masses and their diameters. We also know how much of the energy radiated by their star strikes these planets’ surfaces, allowing scientists to estimate their temperatures. We can even make reasonable estimates of the light level, and guess at the color of the sky, if you were standing on one of them. And while much remains unknown about these seven worlds, including whether they possess atmospheres or oceans, ice sheets or glaciers, it’s become the best-known solar system apart from our own.

Where are we going?

The next generation of space telescopes is upon us. First up was Wednesday’s launch of TESS, the Transiting Exoplanet Survey Satellite. This extraordinary instrument will take a nearly full-sky survey of the closer, brighter stars to look for transiting planets. Kepler, the past master of transits, will be passing the torch of discovery to TESS.

TESS, in turn, will reveal the best candidates for a closer look with the James Webb Space Telescope, currently scheduled to launch in 2020. The Webb telescope, deploying a giant, segmented, light-collecting mirror that will ride on a shingle-like platform, is designed to capture light directly from the planets themselves. The light then can be split into a multi-colored spectrum, a kind of bar code showing which gases are present in the planet’s atmosphere. Webb’s targets might include super Earths, or planets larger than Earth but smaller than Neptune – some that could be rocky planets like super-sized versions of our own.

Little is known about these big planets, including whether some might be suitable for life. If we’re very lucky, perhaps one of them will show signs of oxygen, carbon dioxide and methane in its atmosphere. Such a mix of gases would remind us strongly of our own atmosphere, possibly indicating the presence of life.

But hunting for Earth-like atmospheres on Earth-sized exoplanets will probably have to wait for a future generation of even more powerful space probes in the 2020s or 2030s.

Thanks to the Kepler telescope’s statistical survey, we know the stars above are rich with planetary companions. And as we stare up at the night sky, we can be sure not only of a vast multitude of exoplanet neighbors, but of something else: The adventure is just beginning.

Bottom line: Worlds orbiting other stars are called exoplanets. How we know they’re out there, plus the potential for finding more via the newly launched TESS mission.

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