NASA

An artist's conception shows NASA's Kepler space telescope observing a planetary transit.

NASA is getting plenty of advice — and sympathy — as it assesses whether its Kepler planet-hunting telescope can be revived after the failure of its reaction-control system. The reactions from scientists and engineers range from repair tips to an Audenesque elegy. Here's a sampling:

How to fix Kepler
The reason why the $600 million Kepler spacecraft can no longer search for planetary transits is that two of its four gyroscopic reaction wheels can no longer spin. Mission managers say Kepler needs at least three of those wheels in working order to hold its position still enough to stare at alien stars.

The most recent part to fail is known as reaction wheel 4. The mission's deputy project manager, Charlie Sobeck, told reporters that the Kepler team could try putting some reverse torque on that wheel in hopes of freeing it up.

Two other possibilities were raised by Scott Hubbard, who headed NASA's Ames Research Center during the development of the Kepler mission and is now a consulting professor of aeronautics and astronautics at Stanford University.

One option would be to try turning on reaction wheel 2, which failed last July. "It was putting metal on metal, and the friction was interfering with its operation, so you could see if the lubricant that is in there, having sat quietly, has redistributed itself, and maybe it will work," Hubbard said in a Stanford Q&A.

"The other scheme, and this has never been tried, involves using thrusters and the solar pressure exerted on the solar panels to try and act as a third reaction wheel and provide additional pointing stability," he said. The mission's principal investigator, Ames' Bill Borucki, said on Wednesday the thrusters couldn't hold the spacecraft stable enough for planet-hunting. Nevertheless, it might be one of the options under consideration.

For the time being, Kepler has been put into a holding pattern that should minimize its thruster fuel consumption and give the Kepler team several months to weigh all the options, the costs and the potential scientific benefits.

Going beyond Kepler
Even if the Kepler spacecraft can't be revived, Borucki says that only half of the data collected so far have been fully analyzed. He estimates it'll take another two years or so to complete the analysis.

Meanwhile, NASA has just given the go-ahead its next planet-hunting satellite: the Transiting Exoplanet Survey Satellite, or TESS. That $200 million project would put a telescope array in space in 2017 to perform an all-sky survey, looking for exoplanets in orbit around the nearest and brightest stars. That strategy is markedly different from the one used by Kepler, which stared at a relatively small patch of sky straddling the constellations Cygnus and Vega.

This October, the European Space Agency plans to launch a space probe called Gaia to conduct a census of more than a billion stars in the Milky Way. Gaia could detect thousands of distant planetary systems, and measure their orbits and masses using a technique known as astrometry.

ESA is working on another planet hunter called the Characterizing Exoplanets Satellite, or CHEOPS, which is due for launch in 2017. CHEOPS would conduct high-resolution transit observations of stars that have already been found to host planets. 

The $8.8 billion James Webb Space Telescope, which NASA bills as the successor to the Hubble Space Telescope, could conceivably analyze the atmospheres of alien planets. It's currently due for launch in 2018.

Paying tribute to Kepler
NASA's associate administrator for science, John Grunsfeld, said it's too early to consider Kepler "down and out." But many astronomers fear that Kepler's planet-hunting days are finished.

"I think 'The mission is not over' means 'the mission is over,'" Caltech's Mike Brown said in a Twitter update on Wednesday. "Might be other things it can do. But, kids, I think the mission is over."

Alan Boss, an astrophysicist at the Carnegie Institution for Science who's part of the Kepler team, was similarly downbeat. In an email sent to AAAS MemberCentral, he called this week's setback a "disaster":

"I am afraid that the loss of this second reaction wheel effectively means the partial loss of Kepler's main science goal: determining the frequency of Earth-sized planets orbiting their stars at distances such that liquid water could occur on the planets' surfaces. Kepler has taken an outstandingly impressive four years of data, but we still need another three or so years of outstandingly impressive data to be certain of the frequency of Earth-size planets. Right now we have enough data to make an intelligent extrapolation about what that number is, but that is not the same as actually determining that number. Kepler was planned to do that for us. There is no other mission in sight that can reproduce for us what Kepler was in the process of doing. The upcoming (2017) NASA TESS Mission will help to push the exoplanet field forward, but it is not designed to find Earthlike planets around sunlike stars, like Kepler was."

"This is one of the saddest days in my life. A crippled Kepler may be able to do other things, but it cannot do the one thing it was designed to do."

Another Kepler team member, Geoff Marcy of the University of California at Berkeley, told KQED that he felt dizzy and teary-eyed over the spacecraft's situation. "It’s a loss for our species," he said. "That sounds dramatic, but we pride ourselves as a species of exploration, seeking answers beyond the horizon, answers about our place in the universe. And Kepler was answering those questions."

Marcy went so far as to tweak W.H. Auden's poem "Funeral Blues" to pay tribute to Kepler. Here's the astronomer's elegy to a spacecraft:

Stop all the clocks, cut off the Internet,
Prevent the dog from barking with a juicy bone,
Silence the pianos and with muffled drum
Bring out the coffin, let the mourners come.

Let jet airplanes circle at night overhead
Sky-writing over Cygnus: Kepler is dead.
Put crepe bows round the white necks of doves,
Let the traffic officers wear black cotton gloves.

Kepler was my North, my South, my East and West,
My working week, no weekend rest,
My noon, my midnight, my talks, my song;
I thought Kepler would last forever: I was wrong.

The stars are still wanted now; let's honor every one,
Pack up the moon and dismantle the sun,
Pour away the ocean and sweep up the woods;
For nothing will ever be this good.

With thanks to W.H.Auden.

For a video rendition of "Funeral Blues," check out this clip from "Four Weddings and a Funeral."

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA

An artist's conception shows NASA's Kepler space telescope observing a planet making a transit across an alien star. (Star and planet not to scale.)

NASA's planet-hunting Kepler space telescope suffered a second failure in its reaction-wheel control system, forcing a suspension of its search for alien planets while the space agency determines whether the four-year mission is truly finished.

"It's certainly not good news," Charles Sobeck, deputy project manager for the $600 million mission at NASA's Ames Research Center, told reporters Wednesday.

But Sobeck and other mission managers emphasized that there was still a chance that the probe could be revived. "I wouldn't call Kepler down and out just yet," said John Grunsfeld, associate administrator for science at NASA Headquarters.

The problem has to do with the reaction wheels that are part of Kepler's fine-pointing system. The space telescope identifies worlds in far-off solar systems by watching for the telltale dips in starlight when the planet's disk passes over its parent sun. But in order to make those observations, Kepler has to hold itself in a precise position with the aid of four gyroscopic reaction wheels. One of the wheels failed last July, but Kepler could still do the job with the other three.

On Sunday, however, the spacecraft put itself into safe mode when it couldn't stay in its proper orbit around the sun, 40 million miles (64 million kilometers) from Earth. When the mission team did its regular check-up with Kepler on Tuesday, they found that a second reaction wheel wasn't working. In a mission update, NASA said the problem was probably caused by "a structural failure of the wheel bearing."

That forced an end to Kepler's planet quest. "We need three wheels in service to give us the pointing precision to make this work," the mission's principal investigator, William Borucki of NASA Ames, told NBC News.

Sobeck said the spacecraft itself could remain stable as long as it had fuel for its thrusters, but the thrusters aren't capable of providing the precise pointing that Borucki and his colleagues need. Over the next several months, members of the Kepler team will assess their technical options, and gauge what kind of science could be accomplished using those options, said Paul Hertz, astrophysics director at NASA Headquarters. 

There's still a chance that the reaction-wheel system could be restored — for example, by trying to spin the wheel backward and forward, just as you might spin the wheels of a car that's stuck in a snowdrift. Sobeck said it might even be possible to revive the wheel that was shut down last July. "When we turn it on, it just might start spinning, we don't know," he said.

But mission managers also acknowledged that Kepler's planet-hunting days may be over. Hertz pointed out that the spacecraft outlasted its 3.5-year primary mission, and was currently into an extended mission costing $20 million a year.

Even if the spacecraft's control system can't be revived, it will still take another couple of years to analyze the trillions of bits of data already collected, Borucki said. The mission has already identified 132 confirmed planets and 2,740 additional candidates yet to be confirmed. Some of those worlds are thought to lie within the habitable zones of their planetary systems.

"The prime reason for the existence of this mission is to determine whether Earths are common or rare in our galaxy," Borucki said. So far, the evidence suggests that there are billions of Earth-size planets in the Milky Way. Scientists have not yet identified an Earth-size planet in an Earthlike orbit around a sunlike star, but Borucki voiced confidence that the crucial evidence was tucked away somewhere in the readings that have already been beamed down from Kepler.

"I am really delighted, frankly, with what we've accomplished," he said.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the NBC News Science Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with NBCNews.com's stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

M. Showalter / NASA / ESA

An image from the Hubble Space Telescope shows Pluto and its largest moon, Charon, surrounded by four smaller moons. Astronomers have proposed naming P4 and P5 after Vulcan and Cerberus.

Astronomers have decided to go with the people's choice and propose Vulcan and Cerberus (or Kerberos) as the names for Pluto's tiniest known moons, one of the discovery team's leaders said Tuesday. Vulcan bubbled up to the top of the list in a non-binding "Pluto Rocks" contest in February, thanks in part to a strong endorsement from "Star Trek" captain William Shatner. The International Astronomical Union, which traditionally approves celestial names, still has to weigh in on the discoverers' proposal.

"We did not feel rigidly bound by the vote totals, but in the end we decided that Vulcan and Cerberus/Kerberos were pretty good names," said Mark Showalter, a planetary scientist at the SETI Institute who organized the contest. Showalter discussed the selection process in an email to NBC News after Nature reported that the IAU was considering the names.

Shatner, who played Captain James T. Kirk on the original "Star Trek" series, proposed the name Vulcan in honor of the home planet of Kirk's pointy-eared science officer, Mr. Spock. He put out the word to more than a million Twitter followers, and Vulcan ended up receiving 174,062 of the 450,324 votes cast. Cerberus was No. 2 on the list, with 99,434 votes.

Astronomers needed two names — one for the Plutonian moon P4, discovered in 2011; and another for P5, found in 2012. Although Vulcan and Cerberus were the favorites, it was not assured that the discovery team would go with those choices.

Stating the case
Traditionally, Pluto's moons are named after figures of the underworld from Greek or Roman mythology. Cerberus fit that scheme, because that was the name of the dog that guarded the gates of the Greco-Roman underworld. Vulcan, which is the name of the Roman god of fire as well as Mr. Spock's home world, posed more of a challenge.

"For the IAU proposal, I had to make the connection between Vulcan and the Greco-Roman underworld, because I knew that the nomenclature working groups would not be swayed by Star Trek mythology," Showalter explained. "We don't normally associate Vulcan with Pluto, but in fact when you go back to the literature, the Greeks and Romans understood the underworld to encompass everything beneath the surface of the earth, not just the realm of the dead. So Vulcan, the god of lava and volcanoes, really does have a natural connection to underworld.

"That being said, the nomenclature working group has to grapple with the issue that in astronomy, the name Vulcan has previously been associated with a hypothetical object or objects orbiting interior to Mercury. They also will probably have concerns about the fact that Cerberus has already been used as the name of an asteroid. I still believe that it is very important to give the working group latitude in this decision. I remain optimistic that a consensus will emerge."

One possibility would be to use Kerberos as an alternate spelling for Cerberus, to avoid any potential confusion. That's how the discoverers of another moon of Pluto, Nix, got around the fact that there was already an asteroid named after Nyx, the Greek goddess of the night.

Nicknaming an exoplanet
Meanwhile, another celestial naming contest has come to a surprise ending. For weeks, a commercial venture called Uwingu has been running a contest to come up with an unofficial nickname for Alpha Centauri Bb, the closest exoplanet. Thanks to a last-minute surge of vote-buying, the winner of the planet-naming game is "Albertus Alauda."

"I chose this name to honor my grandfather," Jason Lark wrote in his online citation for the name. He explained that Albertus Alauda is the Latin translation of Albert Lark, his grandfather's name.

Uwingu charges $4.99 for each planet nomination, and 99 cents for each vote. A spokeswoman for Uwingu, Ellen Butler, told NBC News in an email Tuesday that Lark "came in with a $742.50 payment last night to take the win." The mass voting is perfectly in accordance with the rules of Uwingu's game.

"I am overjoyed that my nomination won," Lark told NBC News in an email. "I think my grandfather would be very happy, and I hope my citation does him justice. I am very proud of my granddad. As with any other star or planet, they along with their names live on much longer than any one man, and most have a story behind them, such as in the days of old when stars were used to navigate the globe. I would like to think that Albertus Alauda will take its place alongside them in the generations to come, along with the story behind it."

Uwingu was created last year to offer space-based entertainment, to generate revenue and raise money for space science and education projects. The aim is to distribute at least half of the proceeds in the form of grants to programs such as the SETI Institute's Allen Telescope Array, Astronomers Without Borders and the Galileo Teacher Training Program. The contest to nickname Alpha Centauri Bb, which was discovered last year just 4.3 light-years from Earth, brought in about $10,000.

Among the runner-up names were Sagan and Einstein, Ron Paul and Heinlein, Rakhat (the Alpha Centauri planet featured in a sci-fi novel called "The Sparrow"), Tiber (the Alpha Centauri planet that moonwalker Buzz Aldrin made famous in his novel "Encounter With Tiber") and Amara (the first name of the nominator's fiancee). In all, more than 1,200 names were nominated.

Neither Albertus Alauda nor any of those other names has official status with the IAU. In a stinging news release, the IAU said Uwingu's campaigns "will not lead to an officially recognized exoplanet name, despite the price paid or the number of votes accrued."

There is currently no IAU-sanctioned process for approving popular names for the hundreds of extrasolar planets detected beyond our solar system. Instead, astronomers take the name of the star (for example, Alpha Centauri B or Kepler-62) and tack on a letter of the alphabet, starting with "b." (Hence, Alpha Centauri Bb or Kepler-62f.) For the time being, the IAU is sticking with that system, although it said members would discuss establishing a friendlier naming scheme this year.

Meanwhile, Uwingu's "baby book of names" for exoplanets remains open for business. "Also, next week we'll debut a new way to engage in exoplanet naming," Uwingu's CEO, planetary scientist Alan Stern, said in an email.

More about exoplanet names:

• Who gets to name alien planets?
• Newfound planets need better names
• Why Pluto can't have a Mickey moon

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

L. Calcada / IAU

An artist's conception shows an exoplanet and its twin suns, as seen from the surface of a moon.

A fledgling commercial venture called Uwingu stirred up an international controversy when it started soliciting friendlier names for planets beyond our solar system. The International Astronomical Union issued a statement saying that Uwingu's pay-to-play scheme has "no bearing on the official naming process," and that the IAU is the "single arbiter" on the names for all celestial objects.

But is it?

How about Tatooine? Or UGA-1785? Those are the casual nicknames sanctioned by NASA for a planet known officially as Kepler-16b, and a planetary system called Kepler-37 (although "UGA-1785" doesn't sound like much of an improvement over Kepler-37). It certainly looks as if nicknaming exoplanets is becoming a new frontier on the final frontier, regardless of what the IAU says.

The IAU may get into the act as well: The international organization says it will discuss the idea of having popular names for exoplanets this year. Meanwhile, Uwingu is sticking to its guns. "I think that it's really presumptuous of the IAU to think that they own the sky," one of the venture's founders, planetary scientist Alan Stern, told NBC News.

Paying to take part
One of the extra twists to the controversy is that Uwingu is using its exoplanet-naming contest as a fundraising tool. It costs $4.99 to put a name on the unofficial ballot, and each vote for a planetary name costs 99 cents. Uwingu plans to give half of the proceeds from its contests to space science and educational projects.

The current contest is aimed at coming up with a name for Alpha Centauri Bb, the exoplanet that's closest to our own solar system. Right now, the name leading the list is "Rakhat," a fictional planet made famous in "The Sparrow," Mary Doria Russell's spiritually minded sci-fi novel. Other names on the list include Sagan, Fraggle Rock and Ron Paul. The contest ends at midnight ET Monday.

The fact that people are paying to stuff an exoplanetary ballot box particularly rankled the IAU, which compared the scheme to the International Star Registry and the Lunar Embassy. This week's statement said the IAU "dissociates itself entirely from the commercial practice of selling names of planets, stars or or even 'real estate' on other planets or moons. These practices will not be recognized by the IAU and their alternative naming schemes cannot be adopted."

That statement, in turn, rankled Uwingu's board of advisers, including University of Geneva astronomer Xavier Dumusque, who led the Alpha Centauri Bb discovery team.

"It is unfair to characterize this citizen participation in astronomical nomenclature as being anything like those organizations that purport to sell astronomical objects to the public," the advisers said in a statement emailed to NBC News. "Uwingu's mission is scientific and educational and directly benefits the space science community. It provides a means by which ordinary citizens can feel connected to and help support the discoveries of exoplanets that continue to excite and astonish the human imagination."

Planetary precedent
NASA is already doing that: Tatooine, for example, refers to a planet detected by NASA's Kepler telescope that orbits a binary star system — just like the fictional planet of the same name in the "Star Wars" saga.

UGA-1785 is of more recent vintage, paying tribute to the University of Georgia. "Knowing my UGA history, I knew that the light from this star began its journey toward the Kepler telescope in 1801, the same year that the Franklin College was founded and that classes began at UGA," Franklin College Dean Alan Hunter said in a news release announcing NASA's blessing for the name.

Closer to home, NASA uses the name "Mount Sharp" for the Martian mountain that's due to be the ultimate destination for the Curiosity rover, even though the IAU has named the peak "Aeolis Mons." The Sharp name pays tribute to the late Robert P. Sharp, a geologist who studied formations on Earth as well as on Mars.

Is there any harm in having Mount Sharp as well as Aeolis Mons? Or Rakhat as well as Alpha Centauri Bb? It might get confusing if there were lots and lots of names for the same exoplanet, but it's not a problem to have a friendly name as well as a scientific name for the same object. After all, if it walks like a duck, and talks like a duck, it can also be an Anas platyrhynchos. And nobody get upset over having multiple names for the Whirlpool Galaxy, a.k.a. Messier 51a, a.k.a. NGC 5194.

But what do you think? Cast a vote in our survey (no charge!), and leave your comments below.

More about the name game:

• IAU: You can't buy exoplanet names
• Uwingu: IAU is ruining our reputation
• How an exoplanet made a love connection

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA's Kepler planet-hunting probe has identified two potentially habitable planets only a little bigger than Earth, circling a star that's 1,200 light-years away. The planets could conceivably be covered by a global ocean, and they may well lead the growing list of alien worlds that can host life as we know it.

"These two planets are our best candidates for planets that might be habitable," said Bill Borucki, a space scientist at NASA's Ames Research Center who is the principal investigator for the $600 million Kepler mission.

The two habitable-zone planets, Kepler-62e and Kepler-62f, are part of a five-planet system that lies in the constellation Lyra, within a patch of sky that's been monitored by the Kepler space telescope over the past four years. The Kepler-62 parent star is about two-thirds the size of our own sun and about a fifth as bright.  Three of the star's confirmed planets circle the star in orbits so close that they'd be too hot for life. But the e and f planets are considered to lie in a zone where liquid water could exist, a ring of space that's defined as the habitable zone.

Water worlds?
Two members of the Kepler science team say their modeling suggests the two planets could be "water worlds" — with no land in sight.

"These planets are unlike anything in our solar system. They have endless oceans," Lisa Kaltenegger, an astronomer at the Max Planck Institute for Astronomy and the Harvard-Smithsonian Center for Astrophysics, said in a news release. "There may be life there, but could it be technology-based like ours?"

The report on the Kepler-62 system was published online on Thursday by the journal Science, and was the focus of a NASA news conference timed to coincide with publication. The water-world analysis, authored by Kaltenegger and Harvard's Dimitar Sasselov and Sarah Rugheimer, is contained in a separate paper that has been accepted for publication in The Astrophysical Journal.

The characterization of the two planets' habitability is based on an analysis of their size, plus what's known about the parent star. The Kepler data can show how wide a planet is, and how quickly it makes its orbit, by analyzing the telltale dips in light as the planet passes over its parent star. But Kepler can't make direct observations of a planet's mass. So, in Kepler-62's case, scientists had to make educated guesses about the planets' mass, composition and whether they had atmospheres.

Kepler-62e is 1.6 times as wide as Earth and orbits its star every 122.4 Earth days. Kepler-62f is 1.4 times Earth's width, with an orbital period of 267.3 Earth days. "It's highly likely they're rocky planets," Borucki told NBC News. "They might be water worlds, but they are so different, we just don't know."

David A. Aguilar / CfA

This artist's conception shows Kepler-62f as an ice-covered world, and Kepler-62e as an Earthlike planet with dense clouds. Other planets follow closer-in orbits and are not considered habitable.

NASA Ames / JPL-Caltech

The diagram compares the planets of the inner solar system to Kepler-62, a five-planet system about 1,200 light-years from Earth in the constellation Lyra. The five planets of Kepler-62 orbit a star classified as a K2 dwarf, measuring two-thirds the size of the sun and one-fifth as bright.

What would life be like?
Astrobiologists say the fact that the planets are bigger than Earth wouldn't be an obstacle for life. In fact, some experts argue that a super-Earth is more likely to have life than an Earth-sized planet. "If you and I walked on it, our weight would double," Borucki said. "But my weight has doubled since I was a teenager ... so we could do it."

If the planets had atmospheres like Earth's, Kepler-62e's surface temperature would be 86 degrees Fahrenheit (30 degrees Celsius), while Kepler-62f's temperature would be 19 degrees below zero F (-28 degrees C), Borucki said. "You'd see the sun being substantially larger than our sun, because it's so much closer," he said. "But it'd be darker, like walking around on a cloudy day."

In their research paper, Kaltenegger and Sasselov assume that Kepler-62e has a slightly cloudier atmosphere than Earth's, and that Kepler-62f has a thick carbon-dioxide atmosphere with a strong greenhouse effect. Without a thick atmosphere, Kepler-62f could get chillier than Mars. It might even look more like a Europa-style iceball than a Kevin Costner-style water world.

"Kepler-62e probably has a very cloudy sky, and is warm and humid all the way to the polar regions," Sasselov said. "Kepler-62f would be cooler, but still potentially life-friendly. The good news is, the two would exhibit distinctly different colors and make our search for signatures of life easier on such planets in the near future."

Habitable worlds ahead
Kepler-62e and Kepler-62f aren't the first habitable-zone planets to be identified by the Kepler team, and they won't be the last. A year and a half ago, Kepler-22b came to light as the mission's first potentially habitable planet. It's 2.4 times wider than Earth, which puts it halfway between our planet and Neptune on the size scale. Kepler-47c, unveiled last year, is also a habitable-zone planet — but it's 4.6 times wider than Earth, which makes it Neptune-sized.

This January, the science team discussed the habitability of another candidate planet, then known as KOI 172.02. The existence of that world has now been confirmed under the name Kepler-69c, with a size that's 1.7 times Earth's width. "Today we can announce that this is a bona fide planet," Thomas Barclay, an astronomer at Ames Research Center, said during Thursday's news conference. 

Three months ago, Kepler-69c was hailed as potentially the most Earthlike world detected beyond our solar system, but now researchers say Kepler-62e and Kepler-62f could be stronger contenders.

There will be more contenders ahead: Borucki said about four dozen of the more than 2,700 candidate planets being tracked by Kepler lie within their stars' habitable zones, and it takes about a year to confirm each candidate's existence through detailed analysis. "We really wish we were faster," he told NBC News. "I really wish we could knock off one a week."

Boruckin and his colleagues are poring through the oceans of observations coming in from the Kepler telescope, and although the spacecraft has had its problems, he's hoping that the flood of data will continue for years to come.

"When you're born a scientist, they leave out the gene for saying, 'We have enough data,'" Borucki joked.

More about the planet hunt:

• Alien Earths in our backyard?
• 17 billion hot Earths in our galaxy
• NBC News on planets | Cosmic Log on Kepler

Borucki, Kaltenegger, Sasselov and Barclay are among 64 authors of the Science paper, "Kepler-62: A Five-Planet System with Planets of 1.4 and 1.6 Earth Radii in the Habitable Zone." Barclay and Borucki are among 31 authors of "A Super-Earth-Sized Planet Orbiting in or near the Habitable Zone around Sun-like Star," published in The Astrophysical Journal. Kaltenegger, Sasselov and Rugheimer are the authors of "Water Planets in the Habitable Zone: Atmospheric Chemistry, Observable Features, and the Case of Kepler-62e and -62f."

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

PHL @ UPR Arecibo

An artist's conception shows Alpha Centauri Bb, the nearest known exoplanet. Will it end up being called "Amara," or "Tiber," or plain old Alpha Centauri Bb?

Zeb Gray thought naming an exoplanet after his girlfriend would be the perfect tribute to "the eternal love that we share for each other" — and whether or not the name sticks, the decision arguably changed his life. On Friday, Gray asked Amara Somers to marry him, and she said yes.

Did the fact that Gray proposed the name "Amara" for the planet now known as Alpha Centauri Bb have anything to do with the way his more personal proposal was received? "I think it weighed on her decision," Gray, a 25-year-old security guard from Carson City, Nev., told NBC News.

The planet-naming gap
Amara is currently the top vote-getter in Uwingu's online contest to give Alpha Centauri Bb, the closest-known exoplanet, a more mellifluous name. Traditionally, the International Astronomical Union has had the job of naming celestial bodies — but for now, the IAU has held off on setting up an exoplanet-naming system. Instead, astronomers refer to alien worlds using a combination of the star's name (for example, Alpha Centauri B) and a lower-case letter (which is where that second "b" comes from).

Uwingu, a space-themed entertainment venture, has stepped into the gap with a system that lets users suggest planet names for $4.99, and cast ballots for 99 cents a vote. Half of the proceeds will go to support space science and education projects.

The contest to rename Alpha Centauri Bb runs until April 15, and although the resulting name won't have any official standing with the IAU, Gray would love to see Amara win. "I'm glad to see it has a decent lead, but that could go away pretty quickly," Gray said.

Uwingu

Zeb Gray pays tribute to his fiancee, Amara Somers, with an online card as well as an exoplanet name suggestion.

It helps that Amara is also the name of a magical world featured in Graham Edwards' "Stone" science-fiction trilogy. In Edwards' books, Amara is also known as Stone. It's structured like a spiraling stone wall, and inhabited by hundreds of civilizations.

There's another contender with a strong science-fiction connection, and a high-profile backer to boot. The name "Tiber" is favored by Apollo 11 moonwalker Buzz Aldrin, who's the co-author of a 1977 sci-fi novel titled "Encounter With Tiber." The Tiberians hail from a planet in the Alpha Centauri, and that's one of Aldrin's selling points.

"Don't forget to vote for TIBER in the contest to replace the name for Alpha Centauri Bb," Aldrin told his nearly 800,000 followers in a Twitter update last week. As of this writing, Tiber is No. 17 on the charts with 35 votes — ranking below Amara as well as Heinlein, Pele, Sagan, Asimov and Ron Paul.

Wooed by a moon
Gray, who met Somers at the state agency where they both work four months ago, isn't the first guy to impress a woman by naming a celestial body after her. When Naval Observatory astronomer James Christy discovered Pluto's biggest moon in 1978, he proposed naming it "Charon" — not only because Charon was the ferryman of the dead in Greek mythology, but also because the name paid tribute to his wife, Charlene.

("Char" was Christy's pet nickname for his wife. In her honor, the name is often pronounced "Shar-on" rather than "Care-on, " which is the pronunciation associated with the Greek ferryman. That's one of the many fun facts you'll find in my book, "The Case for Pluto.")

Is it really worth all this fuss to give Alpha Centauri Bb a better name? Astronomer Xavier Dumusque, the lead author of the paper that announced the exoplanet's discovery last year, thinks so.

"I would definitively endorse the name for public outreach and lectures," Dumusque told NBC News in an email. "In astronomy, we have some chance to be able to make people dream, by showing a wonderful picture, by discovering new worlds. If someone is interested in astronomy, he should not face troubles to understand all the nomenclature. Therefore, giving memorable names for planets is one way to get more people interested in our wonderful research."

Do you agree? What names would you suggest? Check out the Uwingu list, and feel free to leave your suggestions as comments below.

More about the celestial name game:

• Baby name book to raise science funds
• Why Pluto can't have a moon named Mickey
• Newfound planets need better names

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday.

MIT

An artist's conception shows the Transiting Exoplanet Survey Satellite, or TESS, in space. (Planets not to scale.)

NASA has selected two new space missions for launch in 2017: a satellite that can scan the entire sky for exoplanets and a space station experiment that can monitor cosmic X-ray emissions. The Transiting Exoplanet Survey Satellite (TESS) and the Neutron-star Interior Composition Explorer (NICER) won out at the end of a selection process that took more than two years.

"With these missions we will learn about the most extreme states of matter by studying neutron stars, and we will identify many nearby star systems with rocky planets in the habitable zone for further study by telescopes such as the James Webb Space Telescope," John Grunsfeld, NASA's associate administrator for science, said in a statement Friday.

Under the terms of NASA's Explorer Program, the TESS mission will be budgeted at no more than $200 million, and NICER's mission costs will be capped at $55 million. Those price tags exclude the cost of the launch vehicle.

Planet hunter
TESS is designed to follow up on NASA's Kepler mission, which is surveying a patch of sky in the constellations Cygnus and Lyra for extrasolar planets. Like Kepler, TESS would detect other worlds by looking for the faint dips in starlight as they make regular transits across their parent suns. TESS' array of wide-angle cameras would take in much more territory, however.

"TESS will carry out the first space-borne all-sky transit survey, covering 400 times as much sky as any previous mission," principal investigator George Ricker, a research scientist at the Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research, said in a statement. "It will identify thousands of new planets in the solar neighborhood, with a special focus on planets comparable in size to the Earth."

The mission's scientists say it will be possible to study the masses, sizes, densities, orbits and atmospheres of a wide range of planets, including a sampling of the rocky worlds in the habitable zones of nearby planetary systems. "The selection of TESS has just accelerated our chances of finding life on another planet within the next decade," said MIT planetary scientist Sara Seager.

TESS won out over another planet-hunting mission designed to study alien atmospheres, known as the Fast Infrared Exoplanet Spectroscopy Survey Explorer or FINESSE.

NASA

An artist's conception shows the boxlike NICER array attached to the International Space Station.

Star watcher
NICER is an instrument that's about the size of a college dorm-room refrigerator, equipped with an array of 56 telescopes that can measure the variability of cosmic X-ray sources — a method known as X-ray timing. It's designed to explore the exotic states of matter within neutron stars and reveal their interior and surface compositions. The device can also monitor the stars' positions as a navigational aid.

"Our technology demonstration will establish the viability of spacecraft navigation using neutron stars, while the same instrument gives scientists an important new tool with which to better understand these stars that can serve as navigation beacons," principal investigator Keith Gendreau of NASA's Goddard Space Flight Center said in a news release.

NICER would be brought to the International Space Station aboard a Japanese HTV robotic transport craft or a SpaceX Dragon cargo capsule, and attached to the station's exterior.

NASA's Explorer Program is designed to provide frequent, low-cost access to space for astrophysics and solar science missions. The program has launched more than 90 missions, starting with Explorer 1 in 1958. The most recent Explorer mission to be launched was the Nuclear Spectroscopic Telescope Array, or NuSTAR. The next one is the Interface Region Imaging Spectrograph, or IRIS, due for launch sometime in the next couple of months.

More about exoplanets:

• How to take a trip to Alpha Centauri
• What's so super about super-Earths?
• Cosmic Log archive on planets

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

L. Calcada / N. Risinger / ESO

An artist's conception shows the planet orbiting Alpha Centauri B, a member of the triple-star system that's closest to Earth. Alpha Centauri B is the most brilliant object in the sky, with Alpha Centauri A at lower left and our own sun visible as a bright speck at upper right.

The closest known exoplanet is currently called Alpha Centauri Bb, but the folks behind Uwingu want you to come up with a cooler name.

"It might be Pandora. Who knows?" said planetary scientist Alan Stern, Uwingu's co-founder and chief executive officer.

As fans of the James Cameron sci-fi blockbuster "Avatar" know, Pandora is the name of the moon in the Alpha Centauri system where the movie's action takes place. In science fiction, planets beyond our solar system have colorful names. But in reality, exoplanets merely have designations that are based either on the name of the star they orbit (like Alpha Centauri Bb) or on the name of the probe that discovered the world (like Kepler-37b)

The International Astronomical Union, which usually takes the lead role in naming celestial objects and features, has held back on creating an exoplanet-naming process. So Stern and his partners set up Uwingu to fill the vacuum — and raise some funds for research and education in the process.

Starting today, Uwingu is taking nominations for Alpha Centauri Bb's new name, at a price of $4.99 per suggestion. For 99 cents per vote, Uwingu's registered users can pick their favorite name. The name that has the most votes when the contest ends on April 15 will be crowned the people's choice. It won't carry any weight with the IAU, but Stern is hoping that the name will stick.

"There are people in the world who think astronomers own the sky, and what we're effectively saying is, it's the people who own the sky," Stern said.

The user who suggests the winning name will receive recognition and prizes from Uwingu. There'll be additional yet-to-be-specified prizes for runner-ups, and for those whose name suggestions reach the 100-, 1,000- and 10,000-vote level. Uwingu already has a list to start with, since it's been in the exoplanet-naming business for several months.

"Older names will be grandfathered in, but I think the new ones will soar past these," Stern told NBC News. (The current top vote-getter is Heinlein, a name that pays tribute to the science-fiction master Robert Heinlein.)

Proceeds from the contest will be distributed according to Uwingu's formula, which puts half of the money into a fund to be given out as grants. Uwingu is structured as a commercial venture, so the rest of the money helps pay the venture's bills. Stern realizes that having people pay to suggest planetary names with no official standing may be controversial, and he's willing to take the heat.

"Just spell our name right," he said.

His supporters include one of the world's foremost planet-hunters, Berkeley astronomer Geoff Marcy, who is one of Uwingu's advisers. In an email, Marcy told NBC News he thought the idea of naming Alpha Centauri Bb sounded "marvelous."

"It should be fun and creative," Marcy said. "It hurts no one, and generates funding for research. What a perfect antidote to the modern crunch on funding in pure research!"

Uwingu's critics include Caltech astronomer Wladimir Lyra, who came up with his own proposal for naming extrasolar planets a few years ago. He's not crazy about the pay-for-play naming system. "What I would advocate is a classical way of naming the planets from our own myths, the way we name features on planets in our own solar system," Lyra told NBC News. "We can draw upon the expertise that the IAU has for naming things."

As long as people understand what they're buying — and what's not for sale — Uwingu's contest looks like an interesting and harmless experiment. Heck, it might even push the world's astronomers to reach consensus on names for the most prominent exoplanets. But what do you think? Feel free to weigh in with your comments below.

Update for 9:35 p.m. ET: I originally wrote that Uwingu is structured as a for-profit venture, and that the company's partners will receive some of the proceeds — but in a follow-up exchange, Stern said that Uwingu is a long way from making a profit. Half of the revenue goes to a fund for research and education grants, and the other half helps pay the bills.

"Uwingu was to find a new way to fund space research and education in tough times. Some of us wrote checks and put some pretty serious money into getting the company started, and each of the members of this company has contributed hundreds and in some cases thousands of hours to developing this since 2010," Stern said in an email. "None of us has received even a dime from the Indiegogo campaign or any funds we've earned on sales since we debuted. This is a labor of love."

More about exoplanets and their names:

• Mission to Alpha Centauri by 2011?
• How to take a trip to Alpha Centauri
• Newfound planets need better names

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Dunlap Institute for Astronomy and Astrophysics; Mediafarm

An artist's rendering shows the HR 8799 planetary system at an early stage in its evolution, with HR 8799c in the foreground. That giant planet orbits its parent star at a distance comparable to Pluto's distance from our sun.

Astronomers say they've confirmed the presence of water vapor and carbon monoxide in the atmosphere of a giant planet beyond our solar system, thanks to the most detailed spectroscopic scan ever made.

The observations, detailed Thursday on the journal Science's website, uses a method that could someday be used to sample the air of an alien Earth from light-years away, the researchers said.

"The big surprise was actually that we could do it," one of the study's co-authors, Travis Barman of the Lowell Observatory in Arizona, told reporters. "We can actually see the individual lines of these molecules. ... I personally felt like we would not be able to do what we have done."

This isn't the first time scientists have studied the atmosphere of HR 8799c, a planet about seven times as massive as Jupiter that orbits a star 130 light-years from Earth. The HR 8799 system is special because astronomers can actually pick up the light of several giant planets that orbit outside the glare of their parent star. HR 8799c, for example, follows an orbit similar to the one Pluto traces around our own sun.

That's what makes it possible for astronomers to get the "chemical fingerprint" of the planet's atmosphere. One team did it three years ago with an instrument on the European Southern Observatory's Very Large Telescope in Chile. Another team reported just this week that they did it for four planets in the HR 8799 system using an instrument known as Project 1640 on the Palomar Observatory's Hale Telescope in California.

Higher resolution
Barman and his colleagues said they used the OSIRIS spectrograph on the Keck II telescope in Hawaii to produce a chemical fingerprint with enough resolution to determine which chemicals were present in the atmosphere, and which were not.

They found that the planet had a cloudy atmosphere containing water vapor and carbon monoxide — but not methane, as some researchers had previously suspected. Methane is an ingredient in the atmospheres of our own solar system's giant planets.

RC-HIA / C. Marois / Keck Observatory

This is one of the discovery images of the HR 8799 planetary system, obtained by the Keck II telescope using the adaptive optics system and NIRC2 Near-Infrared Imager. The rectangle indicates the field-of view of the OSIRIS instrument, centered on HR 8799c.

HR 8799c isn't a likely candidate to harbor life as we know it. It's far too gassy and hot, with a surface temperature of 1,800 degrees Fahrenheit, or 1,000 degrees Celsius. But the same spectroscopic method could theoretically be used to analyze the atmospheres of Earthlike planets for signs of life — if the telescope could be made big enough.

"If you wanted to do an Earth-sized planet, you really need a spacecraft, and you really need a very dedicated spacecraft that was designed only for that purpose," said another co-author of the Science study, Bruce Macintosh of the Lawrence Livermore National Laboratory in California.

Barman said it might be possible to detect variations in the surface brightness of extrasolar planets using next-generation, ground-based instruments such as the Gemini Planet Imager. "We might be able to do that within the next few years," he said.

How were planets formed?
The researchers said the readings from OSIRIS also could provide insights into how the planetary system was formed. Theorists have proposed two scenarios for the formation of planets from the disk of gas and dust surrounding an infant star. In the core-accretion scenario, planets form gradually as solid cores grow massive enough to start taking on envelopes of gas from the disk. In the gravitational-instability scenario, planets form almost instantly as parts of the disk collapse on themselves.

"For the first time, we can actually make a statement, a suggestion about the way the system might have formed, which is an extremely difficult thing to do observationally," said the study's lead author, Quinn Konopacky, an astronomer at the University of Toronto's Dunlap Institute for Astronomy and Astrophysics.

The ratio of carbon to oxygen was higher than would have been expected if the planet shared the composition of its parent star and protoplanetary disk. That might have happened because the disk's gas cooled gradually over time, forming water ice that depleted the oxygen from the gas that remained. This is the way most astronomers believe our own solar system formed.

"Once the solid cores grew large enough, their gravity quickly attracted surrounding gas to become the massive planets we see today," Konopacky said in a news release. "Since that gas had lost some of its oxygen, the planet ends up with less oxygen and less water than if it had formed through a gravitational instability."

Not all astronomers think the case is that clear-cut, however. Alan Boss, a theoretical astrophysicist at the Washington-based Carnegie Institution for Science, told NBC News that giant planets as far away from their parent stars as HR 8799c were more likely to be formed through gravitational instability than through core accretion.

In any case, Boss said he doubted that the readings from OSIRIS could rule out either scenario for planetary formation, since so much depends on the details of a particular theory. "Theorists are clever," he said. "It's hard to paint them into a corner."

More about planets:

• Sun's shock waves may have staggered planet formation
• Cosmic wreckage hints at our planet's eventual fate
• NBC News archive on planetary science

The authors of the Science study, "Detection of Carbon Monoxide and Water Absorption Lines in an Exoplanet Atmosphere," include Christian Marois as well as Konopacky, Barman and Macintosh.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

L. Calcada / ESO

This artist's impression shows the formation of a gas giant planet in the ring of dust around the young star HD 100546. This system is also suspected to contain another large planet orbiting closer to the star.

By Clara Moskowitz
Space.com

Astronomers have captured what may be the first-ever direct photograph of an alien planet in the process of forming around a nearby star.

The picture, which captured a giant alien planet as it is coming together, was snapped by the European Southern Observatory's Very Large Telescope in Chile. It shows a faint blob embedded in a thick disk of gas and dust around the young star HD 100546. The object appears to be a baby gas giant planet, similar to Jupiter, forming from the disk's material, scientists say.

"So far, planet formation has mostly been a topic tackled by computer simulations," astronomer Sascha Quanz of ETH Zurich in Switzerland, leader of the research team, said in a statement. "If our discovery is indeed a forming planet, then for the first time scientists will be able to study the planet formation process and the interaction of a forming planet and its natal environment empirically at a very early stage."

The star HD 100546, which lies 335 light-years from Earth, was already thought to host another giant planet that orbits it about six times farther out than Earth is from the sun. The new potential planet lies even farther, about 10 times the distance of its sibling, at roughly 70 times the stretch between the Earth and sun. [Giant Planet In the Making Spotted? (Video)]

The possible planet seems to fit the picture scientists are building of how worlds form. Stars themselves are born in clouds of gas and dust, and after they  form, a disk of leftover material often orbits them. From this disk, baby planets can take shape. That's what appears to be happening here.

For example, the new photo reveals structures in the disk surrounding the star that could be caused by interactions between its material and the forming planet. Furthermore, the data suggest that the material around the planet-blob has been heated up, which is consistent with the planet-forming hypothesis.

Ardila et al. / ESO / NASA / ESA

This composite image shows views of the gas and dust around the young star HD 100546, as seen by the Hubble Space Telescope (left) and from the NACO system on the European Southern Observatory's Very Large Telescope (right).

The observations were made possible by the NACO adaptive optics instrument on the Very Large Telescope, which compensates for the blurring caused by Earth's atmosphere. The instrument also uses a special coronagraph that observes in near-infrared wavelengths to block out the bright light from the star, so as to see its surroundings better.

"Exoplanet research is one of the most exciting new frontiers in astronomy, and direct imaging of planets is still a new field, greatly benefiting from recent improvements in instruments and data analysis methods," said Adam Amara, another member of the team. "In this research we used data analysis techniques developed for cosmological research, showing that cross-fertilization of ideas between fields can lead to extraordinary progress."

The findings are detailed in a paper to appear online in Thursday's issue of Astrophysical Journal Letters.

Follow Clara Moskowitz on Twitter @ClaraMoskowitz or Space.com @Spacedotcom. We're also on Facebook and Google+. 

• Alien Planet Quiz: Are You an Exoplanet Expert?
• A Galaxy Full of Alien Planets (Infographic)
• The Top 5 Potentially Habitable Alien Planets

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NASA / Ames / JPL-Caltech

An artist's conception shows the planet Kepler-37b. This planet is slightly larger than our own moon and orbits its host star every 13 days. Its surface temperature is probably around 427 degrees Celsius (800 degrees Fahrenheit).

The discovery of a strange new world about the size of Earth's moon has shattered the record for the smallest known alien planet, scientists say.

The newfound alien planet Kepler-37b is the first exoplanet discovered to be smaller than Mercury. It whips around its parent star every 13 days and has a roasting surface temperature of about 800 degrees Fahrenheit (427 degrees Celsius), researchers said. It not a promising contender for life, they added.

Astronomers found Kepler-37b and two other, larger planets (called Kepler-37c and Kepler-37d) orbiting a star about 215 light-years from Earth using NASA's prolific Kepler space telescope. Finding such a small exoplanet with the Kepler spacecraft was a stretch, but some attributes of Kepler-37b's parent star made the discovery possible.

The star has few sunspots and is bright relative to its planet, making it easier for the Kepler spacecraft to spot the telltale dimming that takes place when a planet passes in front of its star, which scientists call a transit. That method revealed not just the presence of Kepler-37b, but two siblings traveling in orbits farther from the parent star. [Gallery: The Smallest Alien Planets]

"There are not many signals masking the transit," study leader Thomas Barclay of NASA's Ames Research Center in Moffett Field, Calif., told Space.com. "What makes this exceptional was [that] this dip of brightness was just 22 parts per million."

Too hot to host life
Kepler-37b and its siblings, 37c and 37d, are probably uninhabitable, scientists said. All three planets lie close to their parent star, well inside the Earth-sun distance (called astronomical units, or AU). One astronomical unit is about 93 million miles (150 million kilometers).

The moon-sized Kepler-37b is so close to its parent star, at just 0.10 AU, that it probably has no atmosphere or liquid water on its surface. The next planet out, Kepler-37c, is slightly smaller than Earth and may have an atmosphere, but it orbits the star at 0.14 AU — a location that's not in the star's habitable zone, where liquid water could exist on the surface.

NASA / Ames / JPL-Caltech

As shown in this comparative graphic, two of the three planets orbiting Kepler-37 are smaller than Earth, while the third is twice Earth's size. Kepler-37b is about 80 percent the size of Mercury,

The biggest planet in the newfound alien solar system is Kepler-37d. It is about twice the size of Earth and orbits the parent star at a distance of 0.2 AU.

"This could hold an atmosphere, but it's unlikely to be a rocky planet — more likely to be gassy — simply because of its size. It could hold some kind of liquid at the surface," Barclay said.

The next step, Barclay added, will be to look for Mercury-sized exoplanets at greater distances from the host star Kepler-37. More planets could be orbiting the star and await discovery.

"We're looking at it very carefully," Barclay said. "There's nothing yet, but something may appear in the data."

Starlight tells the tale
Barclay and his team took great care to confirm the existence of planets around Kepler-37. The researchers knew that a dip in the star's brightness identified by the Kepler spacecraft could have come from several types of sources, including another star that might be passing in front of the Kepler-37 target. So they ran a computer simulation to see if the newfound planet candidates could be false positives.

Using a tool called Blender from the Harvard-Smithsonian Center for Astrophysics, the researchers simulated several false positive scenarios in order to eliminate them. The results made researchers more than 99 percent confident that the planet candidates are actual planets, Barclay said.

More about planets from Cosmic Log

The science team managed to obtain a close approximation of the size of the Kepler-37 star, in addition to spotting its planetary retinue. The star's quiescent nature allowed the researchers to measure it with asteroseismology, a technique that uses acoustic oscillations on the star's surface. The method is similar to how researchers probe the Earth's interior with seismic devices during earthquakes.

The uncertainty for a star's size is typically 20 to 30 percent, Barclay said. In this case, using asteroseismology, the researchers narrowed the uncertainty to 3 percent.

Measurements showed that Kepler-37 is about 75 percent the size of Earth's sun and 80 percent as massive. This places the star within the same stellar class as our sun.

The $600 million Kepler mission launched in March 2009, and has found more than 2,740 candidate planets so far. The spacecraft searches for small dips in stars' light caused by orbiting worlds that pass in front of them periodically, dimming their brightness.

Follow Elizabeth Howell @howellspace, or Space.com @Spacedotcom. We're also on Facebook and Google+.

• Tiny Planets Around a Tiny Star (Infographic)
• The Wildest Alien Planets of 2012
• The Strangest Alien Planets (Gallery)

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