For thousands of years, humans have been wondering whether there’s life elsewhere in the universe. Now, the technology finally exists to search for it.
To find extraterrestrial life, be it microbes or intelligent life, scientists need telescopes capable of detecting Earth-like planets in Earth’s neighborhood and ways to detect biological signatures of life or signs of alien technology. While some of these tools already exist, astrobiologists asked the U.S. Congress Dec. 4 to invest in the next chapter of the search for life beyond Earth.
“This is the first time in human history we have the technological reach to find life on other planets,” Sara Seager, a planetary scientist at MIT, said at a House Committee on Science, Space and Technology hearing today. “People will look back at us as the [generation] who found Earth-like worlds.”
Are we alone?
Astrobiology — the study of the origin, evolution, distribution and future of life in the universe — has taken a leap forward over the past few years. Members of the science committee expressed enthusiasm for the field’s progress.
“Astrobiology has become a crosscutting theme of all NASA space science endeavors,” and continued funding is important, said Congresswoman Eddie Bernice Johnson (D., Texas).
The Kepler mission has identified more than 3,500 potential planets outside Earth’s solar system, including 10 that are Earth-size and lie within their star’s habitable zone. And the space-based Hubble and Spitzer telescopes recently imaged the atmospheres of an exoplanet directly.
Meanwhile, the Mars rover Curiosity has found evidence that past conditions on the Red Planet could have supported life. Here on Earth, scientists have found examples of microbes living in the most extreme environments imaginable, from volcanic lakes to glaciers. Find life in such unlikely places suggests it could exist in harsh environments on other planets,
After 50 years, humanity is now in an era when it can provide data for whether life exists elsewhere in the universe, Mary Voytek, NASA’s head of astrobiology, told members of Congress.
The search ramps up
A key part of these efforts will be to look for biological signatures in the atmospheres of other planets. For example, oxygen doesn’t last long by itself, so the presence of oxygen would indicate living organisms were producing it. Another necessity for life on Earth is water, and scientists just announced they have found signatures of water in the atmospheres of five planets (although they are superhot, Jupiter-size planets).
NASA’s TESS (Transiting Exoplanet Survey Satellite) telescope, set to launch in 2017, will search for exoplanets using the transiting method the Kepler mission used to detect planets crossing in front of their host star. The James Webb Space Telescope, scheduled to launch in 2018, will be able to peer more closely at some of the planets detected by TESS.
Ultimately, scientists want to image planets directly, but this requires blocking out light from a star so that a planet would be visible. Using a telescope attachment called an internal coronagraph is one way to do this; another way is to build a star shade, a large object shaped like a flower that could be moved independently in space. Scientists need to try both methods to find one that works, Seager said.
The most optimistic estimate for finding life would be within a decade, using the James Webb telescope, Seager said. But she said that a more realistic approach is needed, including a next-generation telescope to succeed the James Webb telescope.
Then there’s the prospect of intelligent life. Space historian Stephen Dick, currently an astrobiology scholar at the Library of Congress, called for renewing efforts to look for intelligent life via the search for extraterrestrial intelligence (SETI).
“No bio-signatures would be more important than a radio signal — especially if they have something to say,” Dick said.
And if scientists find life out there, then what?
“The plan is to confirm it first, then tell everybody,” Dick said.
I’ve always believed that there is alien life out there somewhere. The universe is just too big of a place, with billions of galaxies each containing billions of stars, solar systems and planets, for not one celestial body (other than Earth) to have intelligent life. I realize that this is an unpopular view among most people, especially the mentally crippled religious nuts who actually believe that God created the entire universe for the sole purpose of human life. But then again, I also realize that people who believe this stupidity are idiots.
One thing is for certain; if aliens were to someday visit us, they would be at least ten-times more advanced than we are, as that’s the level of technology necessary to traverse the incredibly vast distances of space. TGO
Refer to story below. Source: Digital Trends
There have been 20-30 major Hollywood alien apocalypse movies released in the last year or so, and more are on the way. They’re unavoidable. Some of them are cataloged here, but there are almost too many to count. As such, it’s no wonder that scientists have hostile aliens on the brain. Several researchers have released a study that says there is a good chance aliens will come and wipe us out if they think we’re irresponsible, expanding too quickly, or a number of other reasons, reports the IB Times. The researchers point to humanity’s own history of hostility toward unfamiliar humans, chimpanzees, and gorillas as evidence.
“Just as we did to those beings, the extraterrestrials might proceed to kill, infect, dissect, conquer, displace or enslave us, stuff us as specimens for their museums or pickle our skulls and use us for medical research,” says the study, published in the journal Acta Astronautica.
Another argument is that, by nature, if we contact aliens through programs like SETI, which will be relaunching in September, the aliens we contact will have to be more technologically advanced than us to even communicate properly. And if they have more advanced technology than us, they could come to harm us.
“A core concern is that ETI will learn of our presence and quickly travel to Earth to eat or enslave us,” says the study.
But what has really changed since programs like SETI began? Well there are more of us, but that’s about it. There will always be remote danger in discovering something (or someone) you don’t know. That’s science. Honestly, we think the only real danger here is in how much time scientists are spending watching the trailer for Battleship. Perhaps Hollywood is taking its toll.
(P.S. If you meet an alien, please don’t tell it that we’re planning on leaving earth anytime soon. Also, show it that you are compassionate and recycle. And whatever you do, don’t show it Avatar. Maybe then it won’t kill us all.)
There is no doubt in my mind, for whatever that’s worth, that there is alien life out there. The universe is just too vast, and has been in existence for far too long (approximately 13.7 billion years) for Earth to be the single cosmological body with life. In fact, not only do I believe there’s life elsewhere in the cosmos; I believe there is intelligent life. I realize this flies in the face of most people, especially those with religious beliefs who think that God created us in his image and that we, and only we, have a purpose in this universe. Personally, I believe that’s all very touching, very romantic and false. TGO
Refer to story below. Source: SPACE.com
Clara Moskowitz, Astrobiology Magazine,
The search for alien life usually focuses on planets around other stars. But a lesser-known possibility is that life has sprung up on planets that somehow were ejected from their original solar systems and became free-floating in the universe, as well as on small bodies called sub-brown dwarfs, which are stars so small and dim they are not really stars at all, but function more like planets.
Studies show these bodies could potentially host atmospheres and surfaces where some form of extraterrestrial life could take hold.
Researcher Viorel Badescu of the Polytechnic University of Bucharest in Romania recently investigated the possibilities for life on free-floating planets (FFPs) and sub-brown dwarfs (SBDs) that might contain lakes of the chemical ethane. He found that such life is not impossible, though it would be significantly different from life on Earth.
His findings were detailed in the August 2010 issue of the journal Planetary and Space Science.
Sub-brown dwarfs are not large enough to generate the nuclear fusion that powers normal stars. Having failed as stars, they slowly radiate their internal thermal energy as heat and very dim light – hence, they are extremely hard to detect. Both free-floating planets and sub-brown dwarfs don’t always orbit around a parent star, and can be found in interstellar space.
Lacking a star, life on FFPs and SBDs would have to rely on the body’s internal heat and the decay of radioactive elements for energy. “One may expect a rather stable heat release for long periods of time, exceeding two or three times the present age of the solar system,” said Badescu. Though meager, this heat could be trapped on the object by an optically thick atmosphere.
But life needs more than just heat to thrive. Another important ingredient for habitability is a solvent – a liquid environment where important chemical reactions can occur. Life on Earth uses water as a solvent, but that’s not the only option.
“Synthesis of observational data makes it possible to conceive chemical reactions that might support life involving non-carbon compounds, occurring in solvents other than water,” Badescu wrote in his paper.
In particular, Badescu found that ethane – a compound of carbon and hydrogen – could function well as a solvent for alien life. [5 Bold Claims of Alien Life]
Life without water
It seems odd to consider the possibility of life on an object more massive than Jupiter or Saturn, especially since most scientists think such gas giant planets — with their high radiation, hostile atmospheres and potential lack of a planetary surface — would not harbor life as we know it.
But Badescu said that some sub-brown dwarfs might have lakes or oceans of liquid ethane that could prove quite homey to alien microbes.
The main difference between water and ethane for use as a solvent is that water is a polar molecule, meaning one end of the molecule is positively charged, and one end of it is negatively charged. This has proven integral to Earth life, because the polar properties of water enable certain kinds of molecules to dissolve easily in water, while others remain stable.
The molecules that code for life – DNA and RNA – have electrical charge properties that allow them to change their internal structure – the specific order of the base molecules within them – and still have the same overall physical properties. This is all enabled by the way their charge properties interact with the polar quality of water.
That would not be the case with ethane, which is a non-polar molecule. With DNA and RNA in this situation, “small changes in molecular structure may create large changes in molecular behavior,” Badescu said. “That is not acceptable in an encoding biopolymer that must support Darwinian evolution, in which case, the molecule’s physical properties must remain relatively constant when the informational content changes.”
However, the challenge is not insurmountable – a completely different type of molecule could be used to code life’s blueprint on a FFP or SBD.
Searching for life
Ultimately, free-floating planets and sub-brown dwarfs could prove a fertile place to look for extraterrestrial creatures.
Besides their habitable qualities, these bodies seem to be quite common in the universe. Sub-brown dwarfs weighing between 1 and 13 Jupiter masses may be about as common as stars, Badescu said.
“The total number of FFPs and SBDs may exceed the number of stars by two orders of magnitude, although most of them should be low-mass rock/ice planetary embryos ejected from planetary systems in formation,” i.e. not the type with large gaseous atmospheres that would retain the heat required for life, Badescu said. “Thus, it might be conceivable that FFPs and SBDs are the most common sites of life in the universe.”
Given this fact, he advocated ramping up our efforts to search for free-floating planets and sub-brown dwarfs and to characterize them to determine which might be habitable.
“Present day technology does not allow a systematic search for habitable FFPs and SBDs,” Badescu said. “However, the existing observation programs of young star forming regions should be supplemented with activities related to FFP and SBD identification and characterization.”
This story was provided to SPACE.com by Astrobiology Magazine.
I am far more astonished, yes astonished, that certain scientists dispel the notion that there possibly could be life elsewhere in the universe than I am of the contrary. After all, the science of cosmology has proven that there are probably upwards of 150 billion galaxies in the observable universe, some of which may contain as many as 100 trillion stars. With numbers of this magnitude, is it unreasonable to propose that intelligent life may exist in at least 1 other location other than planet Earth? I think not!
I’ve always believed that if the scientific community was to prove, beyond the shadow of a doubt, that UFOs are for real and/or that in fact there is intelligent life out there, that the general population would be kept in the dark about the news. This discovery, if ever made, would completely destroy all religious beliefs as they pertain to humans beings made in God’s image for instance, along with countless other “negative” implications about our existence and our place in the cosmos. And I simply don’t believe that people throughout the world as a whole are ready for this kind of information; certainly not in the year 2011.
Naturally, with the passage of time and our access to more and more media, it will become increasingly difficult for new information regarding extra-terrestrial life to be suppressed, once discovered. But certainly world governments will do their best to disqualify such claims. This is my opinion.
For now, those of us with an open mind do not negate the possibility of intelligent life, much less any form of life, somewhere in the cosmos. The probability that Earth is the only rock in all the universe where life exists is nearly impossible. TGO
Refer to story below. Source: TIME
The question of where life began is one of the enduring mysteries of science. Charles Darwin himself speculated that it might have happened in “a warm little pond,” while modern biologists think the superheated water around seafloor volcanic vents is a more likely spot.
But a far more exotic proposal has been floating around for years: maybe life first arose in outer space and came to earth fully formed. It’s an astonishing idea, but it’s not completely crazy: after all, astronomers have discovered dozens of organic molecules floating in giant interstellar clouds, and meteorites have been cracked apart to reveal amino acids, the building blocks of proteins. (See pictures of meteors that have fallen from the sky.)
It’s no surprise, then, that a paper just published in the online Journal of Cosmology has suddenly grabbed the world’s attention. Titled “Fossils of Cyanobacteria in CI1 Carbonaceous Meteorites” and authored by NASA scientist Richard Hoover of the Marshall Space Flight Center in Alabama, it makes the audacious claim that a meteorite that slammed into France in the 1800s has clear evidence pointing to space-dwelling microbes. “The implications,” says an online synopsis of the paper, “are that life is everywhere, and that life on Earth may have come from other planets.”
Well, maybe. But before anyone gets too excited, a little history lesson is in order. Back in 1996, TIME’s cover trumpeted the astonishing words “Life on Mars.” A NASA scientist claimed he’d found evidence that ancient bacteria had once lived inside a Martian rock that had been picked up in Antarctica (the rock had been blasted from Mars’ surface by an asteroid impact long ago and fallen to earth as a meteorite). Newspapers, magazines and TV broadcasts were all over the story, because while alien visitations are a staple of the UFO crowd, this discovery had a pedigree. Not only was the scientist on NASA’s payroll, it was NASA itself that made the announcement at a major press conference. The paper, meanwhile, had been published in Science, one of the world’s top scientific journals, which gave it even more apparent gravitas. (See reports of the earliest UFO sightings.)
Before long, though, the whole thing went away, as other astronomers took a good look at the evidence and pronounced it completely unconvincing.
Then there was the claim back in the 1960s by Fordham University chemist Bartholomew Nagy that he’d found evidence of life in a meteorite – the very meteorite Hoover is talking about now. That went away too. As did claims in the 1930s that scientists had not only found but also revived dormant bacteria from a meteorite. As did claims in the 1890s of meteorites with fossils inside.
All of this may be why many experts in the field of astrobiology – a perfectly legitimate area of science – paid little mind when an e-mail circulated a few days ago trumpeting the latest life-in-a-meteorite paper. “I get e-mails from them regularly, maybe once every month or two,” says a senior astrophysicist at a major university. “They always sound extremely nutty … so much so that I have never been tempted to investigate more closely.” (See the science of sex in space.)
Blogger and biologist P.Z. Myers puts it a little more pithily: the journal is, he writes, “the ginned-up website of a small group of crank academics.” Some of the articles that have appeared do nothing to dispel this idea include “The Origin of Eternal Life in the Multiverse” and “Sex on Mars: Pregnancy, Fetal Development, and Sex in Outer Space.”
But panspermia – the notion that life wafts through interstellar space, seeding worlds as it goes, is one of the journal’s mainstays. Indeed, a frequent contributor, Chandra Wickramasinghe, of Cardiff University in Wales, has been proving the existence of life in outer space for years. Along with his frequent collaborator, Fred Hoyle, Wickramasinghe has “discovered” viruses and freeze-dried bacteria floating among the stars. (Comment on this story.)
Somehow, though, these revolutionary discoveries have failed to become accepted science. One theory, advanced by some of panspermia’s most avid supporters, is that the scientific establishment simply can’t accept radical new ideas that challenge the conventional wisdom. They laughed at Alfred Wegener, after all, when he proposed the notion of continental drift, and at Barry Marshall when he claimed that bacteria cause ulcers.
It may ultimately turn out that they are wrong to dismiss Richard Hoover as well. But Myers, for one, doesn’t think so. “This work is garbage,” he writes. “I’m surprised anyone is granting it any credibility at all.” As for the Journal of Cosmology, he writes, “I’m looking forward to the publication next year of the discovery of an extraterrestrial rabbit in a meteor.”
In that, however, he may be disappointed. According to blogger David Dobbs, a press release has gone out announcing that the Journal of Cosmology is soon to be no more. The headline on the release doesn’t exactly add to the journal’s credibility: “Journal of Cosmology to Stop Publishing – Killed by Thieves and Crooks.”
View this article on Time.com
For those of you interested in the possibility of extra-terrestrial life, you might find the following article interesting. TGO
Refer to story below. Source: SPACE.com
New findings have roused a great deal of hoopla over the possibility of life on Saturn’s moon Titan, which some news reports have further hyped up as hints of extraterrestrials.
However, scientists also caution that aliens might have nothing to do with these findings.
All this excitement is rooted in analyses of chemical data returned by NASA’s Cassini spacecraft. One study suggested that hydrogen was flowing down through Titan’s atmosphere and disappearing at the surface. Astrobiologist Chris McKay at NASA Ames Research Center speculated this could be a tantalizing hint that hydrogen is getting consumed by life.
“It’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth,” McKay said.
Another study investigating hydrocarbons on Titan’s surface found a lack of acetylene, a compound that could be consumed as food by life that relies on liquid methane instead of liquid water to live.
“If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth,” McKay said.
However, NASA scientists caution that aliens might not be involved at all.
“Scientific conservatism suggests that a biological explanation should be the last choice after all non-biological explanations are addressed,” said Mark Allen, principal investigator with the NASA Astrobiology Institute Titan team. “We have a lot of work to do to rule out possible non-biological explanations. It is more likely that a chemical process, without biology, can explain these results.”
“Both results are still preliminary,” McKay told SPACE.com.
To date, methane-based life forms are only speculative, with McKay proposing a set of conditions necessary for these kinds of organisms on Titan in 2005. Scientists have not yet detected this form of life anywhere, although there are liquid-water-based microbes on Earth that thrive on methane or produce it as a waste product.
On Titan, where temperatures are around minus 290 degrees Fahrenheit (minus 179 degrees Celsius), any organisms would have to use a substance that is liquid as its medium for living processes. Water itself cannot do, because it is frozen solid on Titan’s surface. The list of liquid candidates is very short — liquid methane and related molecules such as ethane. Previous studies have found Titan to have lakes of liquid methane.
The dearth of hydrogen Cassini detected is consistent with conditions that could produce methane-based life, but do not conclusively prove its existence, cautioned researcher Darrell Strobel, a Cassini interdisciplinary scientist based at Johns Hopkins University in Baltimore, Md., who authored the paper on hydrogen appearing online in the journal Icarus.
Strobel looked at densities of hydrogen in different parts of the atmosphere and the surface. Previous models from scientists had predicted that hydrogen molecules, a byproduct of ultraviolet sunlight breaking apart acetylene and methane molecules in the upper atmosphere, should be distributed fairly evenly throughout the atmospheric layers.
Strobel’s computer simulations suggest a hydrogen flow down to the surface at a rate of about 10,000 trillion trillion molecules per second.
“It’s as if you have a hose and you’re squirting hydrogen onto the ground, but it’s disappearing,” Strobel said. “I didn’t expect this result, because molecular hydrogen is extremely chemically inert in the atmosphere, very light and buoyant. It should ‘float’ to the top of the atmosphere and escape.”
Strobel said it is not likely that hydrogen is being stored in a cave or underground space on Titan. An unknown mineral could be acting as a catalyst on Titan’s surface to help convert hydrogen molecules and acetylene back to methane.
Although Allen commended Strobel, he noted “a more sophisticated model might be needed to look into what the flow of hydrogen is.”
Scientists had expected the sun’s interactions with chemicals in the atmosphere to produce acetylene that falls down to coat the Titan surface. But Cassini mapped hydrocarbons on Titan’s surface, it detected no acetylene on the surface, findings appearing online in the Journal of Geophysical Research.
Instead of alien life on Titan, Allen said one possibility is that sunlight or cosmic rays are transforming the acetylene in icy aerosols in the atmosphere into more complex molecules that would fall to the ground with no acetylene signature.
In addition, Cassini detected an absence of water ice on the Titan surface, but loads of benzene and another as-yet-unidentified material, which appears to be an organic compound. The researchers that a film of organic compounds are covering the water ice that makes up Titan’s bedrock. This layer of hydrocarbons is at least a few millimeters to centimeters thick, but possibly much deeper in some places.
“Titan’s atmospheric chemistry is cranking out organic compounds that rain down on the surface so fast that even as streams of liquid methane and ethane at the surface wash the organics off, the ice gets quickly covered again,” said Cassini team scientist Roger Clark based at the U.S. Geological Survey in Denver. “All that implies Titan is a dynamic place where organic chemistry is happening now.”
Speculation ‘Jumping the Gun’
All this speculation “is jumping the gun, in my opinion,” Allen said.
“Typically in the search for the existence of life, one looks for the presence of evidence — say, the methane seen in the atmosphere of Mars, which can’t be made by normal photochemical processes,” Allen added. “Here we’re talking about absence of evidence rather than presence of evidence — missing hydrogen and acetylene — and often times there are many non-life processes that can explain why things are missing.”
These findings are “still a long way from evidence of life,” McKay said. “But it could be interesting.”
This is awesome! I missed my “calling” in life; I should have been a scientist (astronomer). TGO
Refer to story below. Source: Associated Press
PARIS (AFP) – Astronomers on Wednesday said they had made the first direct capture of a spectrum of light from a planet outside the Solar System, in what was a landmark in the search for extra-terrestrial life.
The light was snared from a giant planet that orbits a bright young star called HR 8799 about 130 light years from Earth, the 14-nation European Southern Observatory (ESO) said in a press release.
HR 8799 has a mass about one and a half times that of the Sun and hosts a planetary system “that resembles a scaled-up model of our own Solar System,” it said.
The target was the middle of three planets — initially spotted in 2008 — that are between seven and 10 times the mass of Jupiter.
The finding is important, because a light spectrum is like a fingerprint, ESO said. Hidden within it are telltales of the chemical elements in the planet’s atmosphere.
“The result represents a milestone in the search for life elsewhere in the Universe,” said ESO.
Until now, astronomers have been able to get only an indirect light sample from an exoplanet, as worlds beyond our Solar System are called.
They do this by measuring the spectrum of a star twice — while an orbiting exoplanet passes in front of it, and again while the planet is directly behind it.
The planet’s spectrum is thus calculated by subtracting one light sample from another.
But the method can only be used if the orientation of the exoplanet’s orbit is exactly right, and only a tiny fraction of exoplanetary systems fall into this category.
HR 8799 is thousands of times brighter than the planet, which means that sifting out the spectrum was a technical exploit.
“It’s like trying to see what a candle is made of, by observing it from a distance of two kilometers (1.2 miles) when it’s next to a blindingly bright 300-watt lamp,” said Markus Janson, who led a team who uncovered the spectrum.
They used an infrared detector on ESO’s Very Large Telescope, located in Paranal, Chile.
A total of 424 exoplanets have now been spotted since the first, 51 Pegasi b, unofficially called Bellerophon, was detected in 1995, according to the website the Extrasolar Planets Encyclopaedia (http://exoplanet.eu/).
It would be fascinating if proof of extra-terrestrial life could be discovered in our lifetime. I’m a bit of a skeptic however. Not that there’s life somewhere else within our solar system, as well as in galaxies beyond our own. I would have to say that there is almost no chance that there isn’t. I just believe that if in fact there is proof of extra-terrestrial life, that NASA would not be allowed to go public with it, at least not in our lifetime. My thinking is that our federal government, if not governments across the globe, would be too concerned over the myriad of social and religious implications this discovery would pose to the masses. This is a complicated issue that would necessitate a great deal of deliberation among world leaders.
As a side note, I find it amusing that the Roman Catholic Church is even remotely interested in science, particularly astronomy. Isn’t this the same organization that condemned Galileo and ruined his life for discovering that the Sun was the center of our solar system and not Earth? Why jump on science’s bandwagon now, they should hold true to their archaic religious beliefs? TGO
Refer to story below. Source: Associated Press
A top NASA official and other leading scientists say that within four or five years they should discover the first Earth-like planet where life could develop, or may have already. A planet close to the size of Earth could even be found sometime this year if preliminary hints from a new space telescope pan out.
At the annual American Astronomical Society conference this week, each discovery involving so-called “exoplanets” — those outside our solar system — pointed to the same conclusion: Quiet planets like Earth where life could develop probably are plentiful, despite a violent universe of exploding stars, crushing black holes and colliding galaxies.
NASA’s new Kepler telescope and a wealth of new research from the suddenly hot and competitive exoplanet field generated noticeable buzz at the convention. Scientists are talking about being at “an incredible special place in history” and closer to answering a question that has dogged humanity since the beginning of civilization.
“The fundamental question is: Are we alone? For the first time, there’s an optimism that sometime in our lifetimes we’re going to get to the bottom of that,” said Simon “Pete” Worden, an astronomer who heads NASA’s Ames Research Center. “If I were a betting man, which I am, I would bet we’re not alone — there is a lot of life.”
Even the Roman Catholic Church has held scientific conferences about the prospect of extraterrestrial life, including a meeting last November.
“These are big questions that reflect upon the meaning of the human race in the universe,” the director of the Vatican Observatory, the Rev. Jose Funes, said Wednesday in an interview at this week’s conference.
Worden told The Associated Press: “I would certainly expect in the next four or five years we’d have an Earth-sized planet in the habitable zone.”
Worden’s center runs the Kepler telescope, which is making an intense planetary census of a small portion of the galaxy.
Unlike the Hubble Space Telescope, which is a general instrument, Kepler is a specialized telescope just for planet-hunting. Its sole instrument is a light meter that measures the brightness of more than 100,000 stars simultaneously, watching for anything that causes a star to dim. That dimming is often a planet passing in front of the star.
Any planet that could support life would almost certainly need to be rocky rather than gaseous. And it would need to be in just the right location. Planets that are too close to their star will be too hot, and those too far away are too cold.
“Every single rock we turn over, we find a planet,” said Ohio State University astronomer Scott Gaudi. “They occur in all sorts of environments, all sorts of places.”
Researchers are finding exoplanets at a dizzying pace. In the 1990s, astronomers found a couple of new planets a year. For most of the last decade, it was up to a couple of planets every month.
This year, planets are being found on about a daily basis, thanks to the Kepler telescope. The number of discovered exoplanets is now well past 400. But none of those has the right components for life.
That’s about to change, say the experts.
“From Kepler, we have strong indications of smaller planets in large numbers, but they aren’t verified yet,” said Geoff Marcy of the University of California at Berkeley. He is one of the founding fathers of the field of planet-hunting and a Kepler scientist.
But there is a big caveat. Most of the early exoplanet candidates found by Kepler are turning out to be something other than a planet, such as another star crossing the telescope’s point of view, when double- and triple-checked, said top Kepler scientist Bill Borucki.
Kepler is concentrating on about one-four hundredth of the nighttime sky, scanning more than 100,000 stars, ranging from a few hundred to a few thousand light years away. A light year is about 5.9 trillion miles. So such planets are too far to travel to, and they cannot be viewed directly like the planets in our solar system.
If there were an Earth-like body in the area Kepler is searching, the telescope would find it, Marcy said. But it can take three years to confirm a planet’s orbital path.
What Kepler has confirmed so far keeps pointing to the idea that there are many other Earths. Before Kepler, those bodies were too small to be seen. Borucki this week announced the finding of five new exoplanets — all discovered in just the first six weeks of planet-hunting. But all those planets were too large and in the wrong place to be like Earth.
When Kepler looked at 43,000 stars that are about the same size as our sun, it found that about two-thirds of them appeared to be as life-friendly and nonviolent as our nearest star.
Marcy, who this week announced finding a planet just four times larger than Earth, does not like to speculate how many stars have Earth-like planets. But when pressed, he said Thursday: “70 percent of all stars have rocky planets.”
“If you are in the kitchen and are trying to cook up a habitable planet, we already know that in the cosmos, all the ingredients are there,” he said.
While astronomers at the convention are excited about exoplanets, Marcy is more skeptical, as is Jill Tarter, director of the SETI Institute, which seeks out intelligent life by monitoring for electromagnetic transmissions. They said there is still the chance that the searches can come up empty.
Marcy said there is the small possibility that planets do not form easily at Earth’s size, and that most are bigger.
Tarter — who was the basis for a character portrayed in the movie “Contact” by Jodie Foster — said: “I always worry that we talk ourselves into thinking we know more than we know.”
Once an Earth-like planet is found in the right place, determining if there are the ingredients for life there will pose another hurdle.
It will require costly new telescopes. A massive space telescope to scan Earth-like planets for oxygen, water, carbon dioxide — and even faint signs of industrial emissions from civilization — would cost about $5 billion.
For now, such a high price is a budget-buster, but that could change. Cornell University astronomer Martha Haynes said: “We are at a very special moment in the history of mankind.”
On the Net:
NASA’s Kepler Telescope: http://kepler.nasa.gov/
NASA’s Exoplanet Exploration Program: http://exep.jpl.nasa.gov/
The Extrasolar Planets Encyclopaedia: http://www.exoplanet.eu/
American Astronomical Society: http://aas.org/