ALIENS 27

Aliens exist. Chances are good that you believe it’s true. Even if you’re not the type of person who regularly tries to visit Area 51, or who once hooked your computer up to the SETI@home network so that your excess processing power could be used to search the skies for signs of intelligent life, you probably still feel that we’re not alone in the universe. Whatever stance you take, science is there to back you up. According to many brilliant minds, the possibility of life on other planets if fairly high. According to others, the probability is so low as to be nearly nonexistent.

But regardless of what science says, Hollywood has plenty of answers of its own, and regularly spits out movies detailing what aliens would be like if they actually did exist. And because Hollywood doesn’t give a damn about what science says (sorry, science), the movie industry has no problems with creating alien life forms with attributes that completely fly in the face of science, and generating fantastical creations that could never actually exist. They imbue these illogical aliens with characteristics such as…

1.

Peacefulness

The Na’vi species in the movie Avatar are an example of a society so peaceful that even if they didn’t have desirable resources on their planet, the humans would probably still want to beat them up just for being such softies. Sure, these oversized blue housecats had no problem kicking some butt when the humans came to destroy the heart of their civilization, but if humans had never shown up they might have continued in their peace-loving ways for all of eternity.

Why It’s Wrong (According to Science)

Aggression in a species is pretty much essential when it comes to developing sentient levels of intelligence. According to Mark V. Flinn, David C. Geary, and Carol V. Ward, humans only started to develop significant levels of intelligence once they’d managed to become dominant over their habitat. At that point, their primary competition started to come from the only creatures smart and tough enough to fight on their level – themselves. It was only because they fought amongst themselves that they developed most of the abilities that distinguish them from monkeys. Sorry, Mr. Cameron, but the advanced Na’vi civilization never would have come to be after they’d spent their entire evolutionary period cuddling and “being one with nature.”

Hugs for everyone!

2.

Being a Huge Insect

We’re not sure exactly what it’s like instead a movie studio during the planning phases of an alien movie, but we guess the dialogue goes something like this. “Hey, what’s something that lots of people think is weird and scary?” “Well, insects are pretty gross.” “Great! Make them huge, make millions of them, and make them want to kill us for no good reason!”

Why It’s Wrong (According to Science)

First off, there’s the physical limit to insect size due to oxygen in the atmosphere. Apparently, the structure that insects use to breathe only works on a small scale, unless there is a huge amount of oxygen floating around. Trust us when we say you wouldn’t have wanted to exist back when the Earth had much more readily-available oxygen, and insects could grow up to eight feet long. Second, according to this awesome site about the Biology of B-Movie Monsters, “…large insects are prone to a mode of failure called buckling.” So even if the bug’s world had a lot more oxygen than ours, those fancy exoskeletons wouldn’t be enough to support their weight. At least that’s one less thing for us to be horribly, terribly terrified of.

Hey, do you think you could chuck the bug spray over here for a sec?

3.

Hydrophobia

In the movie Signs, aliens are attacking humans, and there doesn’t seem to be much we can do to stop them. They’re much more advanced than us (hence, the ability to travel here from their planet), and they’re bent on our destruction. Luckily, there’s a way that we can stop them – and no, it doesn’t involve us all getting baseball bats and turning into Joaquin Phoenix.

Why It’s Wrong (According to Science)

These aliens can’t tolerate the substance that covers a huge proportion of the Earth – water. We totally get the fact that aliens will probably have a different biology than creatures on our own planet. The problem here (aside from the fact that it would be mind-bogglingly difficult for an extraterrestrial being to be non-water-based) is that there is plenty of water everywhere – not just in the cups that creepy little girl leaves around. There’s water in the air around us, water that we leak and exhale from our bodies every second, and even water pooled on the leaves of the cornstalks the aliens walk through in such a cavalier manner. Basically, these aliens couldn’t even have stepped out of their spaceships without some serious protection.

If only he'd packed a dry suit none of this would have happened.

4.

Large Bodies with Small Wings

People have drawn wings on creatures that don’t normally have wings and described fantastical winged creatures from the start of recorded history. There’s Pegasi, fairies, dragons, griffins, and whatever this thing is supposed to be, for starters. It’s easy to imagine that for pretty much every animal that’s ever existed, people have stuck flight appendages on it at some point.

Why It’s Wrong (According to Science)

There’s a reason that all of these winged creatures exist only in our imaginations; the physics behind animal flight are, to quote a certain sassy blonde, “simple and finite.” For example, a bird with a wingspan of about nine feet can support a weight of about 44 pounds. Assuming wing size scales, an alien the size of Watto (from the unfortunate Star Wars prequels) would need a wingspan of about ten or eleven feet at least to support his weight. Instead, he’s got dinky little mini-wings. Sure, he flaps them super-fast, but that’s still not going to heft his chunky lump of flesh around.

One of the most racist Star Wars characters you'll ever meet (http://www.weirdworm.com/the-five-most-racist-star-wars-characters/)

5.

Tentacles (On Land Creatures)

We get that coming up with alien species for movies isn’t always the easiest thing. Movie makers want their aliens to be as different from any sort of life we may have come across as possible. This is quite a task, considering how weird some types of life on earth can be, such as the lampfish or the Bonobo monkey. If these creative minds had to stay within the bounds of stuffy old science, it probably wouldn’t make for very interesting movies. Still, sometimes they go a little too far, like when they put tentacles on creatures that exist primarily on land.

Why It’s Wrong (According to Science)

Aliens like the ones from Independence Day (isn’t it funny how so many aliens don’t have specific species names?) couldn’t possibly exist with those squiggly appendages because creatures with tentacles rely on the surrounding water pressure to keep their tentacles functioning properly. There’s a reason that animals that live on land have rigid structures, and that soft-bodied creatures tend to be small or else stick to the water. The tension of the skin on these alien tentacles simply wouldn’t be enough to hold in the pressure of fluids pumping vigorously enough to whip them around in the air, leading to a rather unfortunate exploding of appendages. We feel like that would end up as a really bad day for some of these supposedly bad-ass aliens.

It's weird to watch the beginning of this scene and realize that all of those poor scientists will soon suffer terrible deaths.

LIFE ON VENUS

Russian scientist claims to have discovered life on Venus

Leonid Ksanfomaliti, an astronomer at Space Research Institute of the Russian Academy of Sciences, claims to have detected signs of life in 30-year-old photographs of Venus. Of course, that's completely ludicrous... isn't it?Science fiction writers of the Golden Age often imagine that a habitable world existed hidden below the deep cloud cover of the Venusian atmosphere, and it made for some great stories - the time I read Ray Bradbury's "All Summer in a Day" in middle school still haunts me. But by the 1960s, the American Mariner probes and their Soviet Venera counterparts had revealed Venus was just about the most inhospitable place imaginable, an acidic world with surface temperatures of about 900 degrees Fahrenheit and pressures nearly 92 times that of Earth.

That's why the new paper by Russian astronomer Leonid Ksanfomaliti, due to appear in the Russian publication Solar System Research, seems to sit slightly outside the scientific consensus. He says that photos taken in 1982 by the Venera 13 probe, which visited Venus in March of that year, depict a "disk", a "black flap", and, perhaps most boldly, "a scorpion." He says the objects "emerge, fluctuate and disappear" in different photographs that were taken from various vantage points, which leads him to what even he admits is an extremely bold claim:

"What if we forget about the current theories about the non-existence of life on Venus? Let's boldly suggest that the objects' morphological features would allow us to say that they are living."

It's hard to say anything for certain without looking at the actual evidence - his article doesn't seem to be online yet - but obviously these claims seem extremely dubious, and this sounds like it's probably just a trick of the light, assuming there's anything there to begin with. So yeah, just to be clear, this is almost certainly nothing.

If you want to play extremophile devil's advocate here, it's worth noting that we've discovered microbes here on Earth that can survive at pressures up to a thousand times that of Earth's surface, which is far worse than what's found on Venus. You could probably find extremophiles here on Earth that could handle the acidity and radiation of Venus, but the 900 degree temperatures are the big deal-breaker here - a 2003 studysuggests that the upper temperature limit for any form of life is probably about 300 degrees, as DNA starts to break apart and lose coherence at that point. So, basically, even a tiny, microbial extremophile is almost certainly impossible on the Venusian surface, let alone a scorpion or disc or black flap.

That said, the notion of life on Venus isn't a completely ridiculous - at least, not the idea of life above Venus. While there's no evidence to support the existence of life in Venus's upper atmosphere, its chemical composition has a lot of gases that don't readily form naturally, and it's possible that there are microbes up there that help produce them. The upper clouds of Venus actually have highly Earth-like conditions, so extremophiles wouldn't even be required for life to survive up there.

As far as these cloud-based microbes go, the current scientific consensus is that the possibility can't be dismissed. Of course, that's a far cry from actually proving there's life on Venus, and even that is still about a million light-years away from scorpions and black flaps hanging out on the Venusian surface.

STAINLESS STEEL DROPPINGS

I first became aware of this collection of pulp-era short stories by author Robert Silverberg when George Kelley posted a picture of the book and its table of contents on his site last fall. The moment I saw Kieran Yanner’s dynamic retro cover I knew this book would have to be mine. I was reminded of the book when posting about my favorite SFF covers from books published in 2011 and promptly ordered a copy. Over the last two days I have immersed myself in the world of pulp-era science fiction and in so doing have discovered the talent that later propelled author Robert Silverberg to Grand Master status.

Pulp-era stories are all too often written off as something of inferior quality and in many ways in a best case scenario the term “pulp” has come to be synonymous with nothing more than guilty pleasure reading. I suspect that there is a great deal of merit in that. Common sense would dictate that in the heyday of pulp magazines publishers were cranking out magazines as fast as they could and authors were expected to follow a formula, write quickly, and be as prolific as possible if they wanted to make a living and keep their work in the public eye. And to be certain there is probably much in the days of pulp science fiction that wasn’t worth reading then and does not merit attention now. By the same token, there are common themes, archetypes, and story structures in pulp adventure stories that resonate with today’s audience. In my childhood it was creators like George Lucas who reached back into the pulp era for inspiration when crafting what would become the pop cultural phenomenon Star Wars. And though some may be loathe to admit it, there is a universality to these tales that are the ancestors of popular stories today.

The stories are often sensational, featuring rugged heroes prone to decisive action, conflict between defined “good guys” and “bad guys”, action over characterization or science, romantic melodrama over reason. These are space yarns, at times little different than their mystery or western counterparts. The setting may be on another planet or on Earth in the far-flung future but the stories themselves are as recognizable to fans of fiction in general as they are to fans of the genre of science fiction.

Planet Stories Books has reprinted 7 of Robert Silverberg’s stories originally published in the short-lived digest Science Fiction Adventures, edited by John Carnell. In the introduction Silverberg sets the stage for what I believe is the proper attitude with which to approach these stories–he relates the story of his first encounter with Planet Stories Magazine and how he found it to be a “treasurehouse of wonders”. He then went on to collect and devour all of the back issues of the magazine. Silverberg relates the circumstances around the creation of these seven stories and where they were originally published and at no time in his introduction does he approach this work with a self-deprecating or apologetic tone. Silverberg remembers the “heady rapture” of the pulp stories of his youth and recalls how both he and Carnell approached Science Fiction Adventures as a way to honor the love they had for Planet Stories.

Please allow me a moment to give a brief synopsis of each novella with my non-spoiler thoughts included.

Slaves of the Star Giants

Lloyd Harkins awakens in a place where quiet, melancholy giants lumber with unknown purpose and 15 foot tall robots crash pell-mell through the woods. Placed unceremoniously in a tribe of barbarians, Harkins soon finds himself at odds with the tribes’ leader and banished back to the savage forest. As events unfold, Harkins begins to suspect that he is merely a pawn in a game much larger than himself and the anger that ignites will lead him to either victory, or to death.

The future-Earth described by Silverberg called to mind other stories that I’ve read, like Jack Vance’s Tales of the Dying Earth and Larry Niven’s A World Out of Time. Technology is akin to black magic to the people who no longer know how to use it or what purpose it had. Some of the nostalgic charm that these older stories often possess was present in this first story mostly in the form of an enormous computer that required tape to be fed into the machine in order to make it function.

Spawn of the Deadly Sea

Earth lies entirely underwater, the result of a long-ago invasion by a mysterious alien race. Humanity exists in two-spheres: the floating cities that are the refuge of the progeny of those that survived the invasion and the vast oceans which are home to the Seaborn, hybrid man-made creatures that were mankind’s last hope to defeat the alien invaders. But alas they were too little, too late. In this far future the world is divided into nine sections of the sea, each ruled over by the Sea-lords, brigands who enact tribute to protect the shipments of goods from one floating city to another. Young Dovirr is tired of city life and longs for the glory he imagines is part of the life of a Thalassarch, ruler of the Sea-lords. With the bravado of untried youth Dovirr gambles and wins a spot on the Garyun, determined to make his dreams of naval conquest a reality. He soon discovers there is more to the sea than the occasional battle with would-be pirates and humanity’s pent up anger over the past alien invasion is just about to find a release.

This story is very much a rousing swash-buckling pirate adventure, yet within those confines it nevertheless touches on some very interesting concepts, like prejudice and mindless obedience. The concept of entire Earth cities being covered and remaining covered with water stirred my imagination and I couldn’t stop the flow of cinematic images of what it would look like to dive these remains.

The Flame and the Hammer

The Emperor of the Galactic Empire is growing old and feeble and grumbles of rebellion from a few wayward planets are beginning to reach his ear. Ras Duyair lives on one of these planets, Aldrynne, the capital planet of a seven planet system. His father, High Priest of the Temple of the Suns has often spoken of the mythological Hammer of Aldrynne, a weapon prophesied to bring down the fall of the Empire. When his father is killed under Imperial interrogation as to the whereabouts of this weapon it soon becomes apparent that the knowledge of what this weapon was or where it can be found has died with him. Ras Duyair flees to a neighboring planet to escape those who believe his father has passed this information down to him and he soon becomes embroiled in a rebellion against the Galactic Empire.

With shades of Isaac Asimov’s Foundation, particularly in the use of an ancient Rome inspired system of government, Silverberg has crafted his version of the tale of a young hero born into obscurity who will rise up to take on an Empire.

Valley Beyond Time

Sam Thornhill lives alone in a peaceful valley, a place of utter tranquility. Or at least he thought he was alone until the arrival of a beautiful woman and a squat man shatter his peace. Soon there are nine people in the valley, six humans and three aliens. As the bliss of Thornhill’s illusions begin to fade he discovers that this majestic valley may not be all that it seems and forces beyond his imagination might never allow any of them to leave.

This is the kind of story you would expect to have been later adapted for an episode of The Twilight Zone. And in some manner it has, for this is a story that has been told many times and in many ways in short story format and also in television shows like the aforementionedTwilight Zone and the various iterations of Star Trek. Despite its familiarity, the themes of freedom and control are as compelling as ever and Silverberg builds the suspense in a satisfyingly deliberate manner.

Hunt the Space-Witch!

When the starship on which Barsac serves lands on the planet Glaurus, he begs leave of his captain to set out to track down an old friend of his to fill a vacant position on the ship. In the years of his absence, Glaurus has become considerably more dangerous and Barsac soon discovers that his friend has gone missing, a possible recruit of the enigmatic Cult of the Space-Witch. As people begin to die around him Barsac becomes more determined to rescue his friend at any cost, even if the cost is his own life.

What sounds as if it would be an incredibly hokey bad-religious-cult story demonstrates that not all pulp stories are created equal and that “space adventures” can sometimes be as dark and sinister and deadly as the cold reaches of space itself.

The Silent Invaders

Major Abner Harris of the Interstellar Development Corps is on his way to Earth for a long overdue vacation. Except that it really isn’t overdue nor is it a vacation. For Major Harris is not really Major Harris, nor is he the Terran male that he appears to be. Harris is really a member of the race of the planet Darruui, a reluctant recruit chosen to infiltrate Earth for reasons that will be revealed as the story unfolds. Harris soon finds he is not alone in his deception and that members of Darruui’s sworn enemy, the Medlin, are also on Earth in the guise of native-born Terrans. In a story worthy of the espionage/counter-espionage of noir detective stories, The Silent Invaders foretells the next stage of the evolution of humanity and examines the lengths people, and aliens, will go to in order to make sure that their self-interests are protected.

This is an interesting addition to the collection because it bucks the tradition of the rest of the stories printed here, and presumably the majority of pulp sf stories, in that it introduces a strong and capable female character into the mix and allows her to be just that. In the introduction Silverberg mentions that he has expanded this story into a novel and I can safely say it is one novel I will be keeping an eye out for.

Spacerogue

Barr Herndon has a grudge, the kind of deep-seated grudge born out of seeing his family murdered and their lands destroyed at the whim of a self-indulgent ruler. Now he is back and it soon becomes apparent that he is looking for revenge and he will stop at nothing, including an almost fanatical devotion to his own gray moral code, to get it.

This is a story of nobles and serfs, a feudal society in a far distant galaxy. More than any other tale in this collection, Spacerogue shocked me. Right from the beginning something happens that I did not see coming and the surprises continue as Herndon gets closer to his desired vengeance.

Hunt the Space-Witch! not high literature. Deep characterization and exhaustive examination of ideas were not the order of the day. These seven novellas were written with magazine space considerations in mind and were written to capture the imagination and to hopefully infuse a sense of wonder in the reader. They were meant to thrill and to excite. Today they are works of pure nostalgia but at the same time they demonstrate that even at an early age Silverberg was talented and imaginative. The stories may follow a predictable pattern but do not always have predictable endings and I was pleasantly surprised with how often I was shocked with a particular story element or direction a story was taking. Characters made decisions I did not anticipate and there was a degree of ambiguity about some of the protagonists that made it hard to like them even when you were on their side. At the same time there is a comfort that comes with the certain knowledge that the short stories in a collection will all have a definite beginning, middle and end and will not be reliant on something esoteric or ambiguous to lend them credibility or to elicit praise.

It is akin to damning with faint praise to say that a story, or in this case a collection of novellas, is “fun”. However, it is not my intention to denigrate Silverberg’s pulp science fiction tales when I say that they are just that–pure, unadulterated FUN. I picked this collection up late yesterday evening and found myself reading well into the night. I awoke early this morning and immediately started where I left off, finishing it later this afternoon while sitting out on my back porch in warm, un-January-like weather. My disappointment when there were no more stories left to read is a compliment to how much I was entertained by Silverberg’s wonder-filled nostalgic science fiction.

Before I leave off I have to give praise to Planet Stories for their book design. I have already mentioned my affection for the cover art, but what makes the book’s presentation special is the nod to the pulp magazines that inspired Silverberg to write these stories in the first place. From the magazine-style Table of Contents to the ad-filled back pages featuring full-page book art and a retro-style subscription page, this book is an homage to a time when science fiction publishing was so very different than what it is today. I should point out that on the publishing data page it erroneously reports that these stories were previously published separately in Planet Storiesmagazine. This does not concur with Silverberg’s introduction in which he talks about the untimely (for him) demise of Planet Stories magazine saying, “I never did get a chance to have some grand and gaudy space adventure published in that grand and gaudy magazine”. As mentioned above these stories were published in Science Fiction Adventures magazine. A minor quibble about an otherwise snappy trade paperback.

And so I leave you with this. Silverberg’s stories are indeed “grand and gaudy”, filled with tropes and trappings that by this era are well worn and sometimes eyed with scorn. But Robert Silverberg is a skilled writer and evidence of that skill is present in these early stories. Where others wrote unrestrained and sometimes incredibly wacky over-the-top pulp, Silverberg concentrated on telling a good story with evidence that he was putting his heart into being a success. Hunt the Space-Witch! is a fun-filled collection of space adventures that open a window to a fascinating period of science fiction history.

THE LAND THAT TIME FORGOT

JOURNEY TO THE EDGE OF THE UNIVERSE

WATERWORLD

KEPLER 154

              

The image above shows the radio signal detected by the 100-meter Green Bank Telescope in West Virginia while scanning the exoplanetary candidate KOI 817 discovered by the Kepler mission. This is the kind of signal SETI scientists would expect to find if an alien civilization is transmitting. 

"We've started searching our Kepler SETI observations and our analyses have generated some of our first candidate signals, which areundoubtedly examples of terrestrial radio frequency interference (RFI)," scientists of the University of California, Berkeley announced on Friday.The detection of these artificial signal provides the UC Berkeley SETI team with a great opportunity to understand the kind of artificial signals they hope to eventually discover.

"These signals look similar to what we think might be produced from an extraterrestrial technology. They are narrow in frequency, much narrower than would be produced by any known astrophysical phenomena, and they drift in frequency with time, as we would expect because of the Doppler effect imposed by the relative motion of the transmitter and the receiving radio telescope," according to the Berkeley team.

For the world to be confirmed, it needs to complete four transits. As one of Kepler's prime mission objectives is to discover Earth-sized exoplanets orbiting within the habitable zone of sun-like stars, we have to wait 3.5 years until Kepler can confirm their existence. If this extraterrestrial life is going through the "radio transmitting" technology phase, then perhaps we might detect them on one of these exoplanets.

Like the Age of Copernicus, the Kepler space telescope's survey of one small swath of the Milky Way is changing mankind's view of the Universe: dramatically increasing popular awareness of the likelihood that life exits beyond our Solar System. 

On December 5, NASA's Kepler mission has confirmed its first planet in the "habitable zone," the region around a star where liquid water could exist on a planet's surface. The newly confirmed planet, Kepler-22b, is the smallest yet found to orbit in the middle of the habitable zone of a star similar to our sun. The planet is about 2.4 times the radius of Earth. Scientists don't yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets.

Previous research hinted at the existence of near-Earth-size planets in habitable zones, but clear confirmation proved elusive. Two other small planets orbiting stars smaller and cooler than our sun recently were confirmed on the very edges of the habitable zone, with orbits more closely resembling those of Venus and Mars. 

Kepler also has discovered more than 1,000 new planet candidates, nearly doubling its previously known count. Ten of these candidates are near-Earth-size and orbit in the habitable zone of their host star. Candidates require follow-up observations to verify they are actual planets. 

"This is a major milestone on the road to finding Earth's twin," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington.

Kepler discovers planets and planet candidates by measuring dips in the brightness of more than 150,000 stars to search for planets that cross in front, or "transit," the stars. Kepler requires at least three transits to verify a signal as a planet. 

"Fortune smiled upon us with the detection of this planet," said William Borucki, Kepler principal investigator at NASA Ames Research Center at Moffett Field, Calif., who led the team that discovered Kepler-22b. "The first transit was captured just three days after we declared the spacecraft operationally ready. We witnessed the defining third transit over the 2010 holiday season." 

The Kepler science team uses ground-based telescopes and NASA's Spitzer Space Telescope to review observations on planet candidates the spacecraft finds. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets. 

Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a sun-like star resembles that of our world. The planet's host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler.  Of the 54 habitable zone planet candidates reported in February 2011, Kepler-22b is the first to be confirmed.

Congressional funding for Kepler — which has identified 1,235 candidate alien planets to date and recently discovered the first exoplanet with two suns in its sky — is due to run out in November 2012,  but an extension may be approved is the new mission proposal is approved. The NASA Kepler team will know by next spring whether it's approved.

"I think the discoveries we're making are showing what could be done if we continue to extend it," said Charlie Sobeck, Kepler deputy project manager at NASA's Ames Research Center in Moffett Field, Calif. "So we're hopeful, but there's no guarantee."

When Kepler launched in 2009, the telescope's science mission was set to run through November 2012 — a lifetime of 3.5 years. But the instrument could operate for six years, or perhaps longer, if it receives more funding, team members have said.

It would cost about $20 million per year to keep the Kepler mission running at its current level of activity beyond November 2012, Sobeck added. The $600 million Kepler observatory launched in March 2009. Its mission is to find roughly Earth-size planets in or near the habitable zones of their parent stars — a just-right range of distances that could support liquid water and, perhaps, life as we know it on the alien worlds.Kepler's overall goal is to help scientists determine just how common such planets may be throughout our galaxy.

In its search for extraterrestrial life, NASA's Kepler space telescope has found two new planets orbiting a distant sun-like star, and the researchers who made the find say these two are the first ever the size of Earth or smaller --a critical factor in the search for life elsewhere in the universe. Until now, scientists said their instruments were not sensitive enough to detect them.

Two newly-found planets, called Kepler-20e and Kepler-20f --announced on December 20-- orbiting a star about 950 light-years away, are too distant to be seen directly. Scientists measured the faint dimming of their host star as they passed in front of it to estimate their size. 

Kepler-20e and f are probably too hot to be friendly to life -- one of them circles its sun in just six Earth days, and the other does it in 19. This newest Kepler find increases the odds that some day soon we will find a planet of just the right size and temperature to have at least a chance of being a habitable.

In less than 20 years, astronomers have gone from not knowing if other planets exist in the universe, to our current Kepler catalog on almost 2000 planets. Our Milky Way galaxy may be home to at least two billion Earthlike planets, a recent study based on initial data from from Kepler space telescope shows -- a number that is actually far lower than many scientists anticipated.

Based on what Kepler's found so far, the study authors think that up to 2.7 percent of all sunlike stars in the Milky Way host so-called Earth analogs. As of this February, Kepler has confirmed 15 new planets and found an additional 1,235 planet candidates, including the smallest planet yet spied outside our solar system. Kepler will collect transit data for a minimum of three and a half years, allowing for a more complete planetary census at a later date.

"There are about a hundred billion sunlike stars within the Milky Way," said study co-author Joe Catanzarite, a scientist with NASA's Jet Propulsion Laboratory (JPL). "Two percent of those might have Earth analogs, so you have two billion Earth analog planets in the galaxy," he added. "Then you start thinking about other galaxies. There are something like 50 billion, and if each one has two billion Earthlike planets, it's mind boggling."

Although the figure seems large, Catanzarite and co-author Michael Shao, also of JPL, say their results actually show that Earths are "relatively scarce," which means a substantial effort will be needed to identify suitable target stars for followup missions designed to study the chemical signatures of Earth-size worlds. The chemical signals may hint whether the planets have oxygen atmospheres, liquid water -- or even signs of life.

The Kepler telescope has been scanning a patch of sky near the constellation Cygnus which can be considered a representative sample of what exists throughout the Milky Way. The Kepler space telescope analyze the light from the 156,000 stars in its field of view searching for stars that dim periodically—signs that significant objects are orbiting these stars.

To extrapolate the number of possible Earths in the Milky Way, Catanzarite and Shao started by defining an Earth analog based on a transiting planet's size and the distance at which the planet orbits its star."A famous 1993 paper calculated the inner and outer distance of the so-called Goldilocks zone"—not too hot, not too cold — "where liquid water could exist on a planet's surface," Catanzarite observed.

"But more recently people have been saying those boundaries are conservative. Maybe you could go closer or farther. For instance, because of greenhouse gases a planet could be farther away and still be warm, or because of clouds, which the previous models didn't take into account, you could be closer but keep the surface cool."

In general, though, an orbit similar to Earth's seems ideal: "Closer than Earth and you'll fry; water would turn to steam. If you're too far, water would freeze into ice."

"People generally agreed that the smallest habitable planet would be 0.8 Earth radii ... or roughly half of Earth's mass. The reason is that a lower mass planet wouldn't be able to hold on to an oxygen atmosphere," Catanzarite said. "Out to two Earth radii is the largest planet we'd call Earthlike. More massive planets start to accumulate thick hydrogen atmospheres, like Neptune or Uranus," with unbearable atmospheric pressures.

Other planets may exist that we can't see because of their orbital inclination, so the team used previous exoplanet data to make mathematical estimates for the probabilities of these unseen worlds.The results published online this month on arXiv.org showed that, according to the traditional boundaries of the Goldilocks zone, 1.4 percent of sunlike stars should have Earth analogs.

If you accept the wider, more modern version of the habitable zone, 2.7 percent of sunlike stars likely host Earths. The study authors predict that Kepler will eventually find 12 Earth analog planets in its field of view — and may have already found 4 such worlds among its initial candidates.

"This study completely underestimates the frequency of Earths," according to MIT planetary scientist Sara Seager, a member of the Kepler science team who noted that  Kepler's just getting started, so its data is far from complete. "Say you're doing a census of the United States," she said. "If you go to California and knock on every door, you can then extrapolate out to the rest of the country. That's what Kepler's doing."

"If Kepler's really going to find the answer in a few years, I'm happy to just wait rather than speculate", Seager said. The other big concern is that, with the data Kepler can collect, it's impossible to say whether a given planet is truly Earthlike. Size alone, for example, doesn't say enough about habitability. "Earth and Venus are about the same mass and size," she said — and by some definitions both worlds fall in our sun's habitable zone.

"To me, for a planet to be called an Earth analog you have to have Earth's mass, size, orbit, and know whether there's liquid water on the surface. But you can't know that until we do atmosphere studies," she said. "Kepler can find only Earth-size planets — we'd never use the term 'Earth analog.'  Some people are expecting the number of Earths to be higher," Catanzarite said, adding that Seager "may be right" and the new estimate is too low, "but it's still unclear."

"We're assuming that for all 156,000 stars, it's possible to detect all small planets of Earthlike radii and orbital distance. If [Kepler] can't, that would make our number an underestimate."

What about the possibility of life not only in the Milky Way, but also in the 50 billion galaxies beyond our galactic home-base?  New findings from diverse fields are are being brought to bear regarding the central question of the 21st century: How common is life in the Universe?  Where can it survive, Will it leave a fossil record, How complex is it. 

For decades, scientists have been debating the conditions that are needed to replicate an Earth-like probablility of complexity beyond the microbial level. There's not much doubt in the minds of most astrobiologists that based on extremophile life we've discovered recently on Earth (see prior posts below), that life on the microbial level will be discovered sometime in the next twenty years on Mars or on one of Jupiter or Saturn's moons.

The three recent key findings for astrobiology are extremophiles, extrasolar planets, and a sense that water may be more ubiquitous even in our own solar neighborhood (in meteors like the Mars' Lafayette, Europa, and the ice frost on polar Mars). This picture has evolved quite suddenly with 1000-plus extrasolar planets found in just the last decade (and none known before around 1995). 

Even in the oldest globular cluster star systems in our Milky Way galaxy -- choked with stars that were born more than 10 billion years ago -- there are enough "metals" to make earth-like worlds. 

According to models of planet formation developed by Harvard's Dimitar Sasselov, a member of the Kepler team, such a planet should be about half again as large as the Earth and composed of rock and water, what the astronomers now call a “super Earth.”for evolved animal life to be present we need to find that sweet "Goldilocks" planet with an exceedingly complex host of conditions present that have given rise the "Rare Earth" hypothesis.

Kepler finds alien planets using what's called the transit method. The telescope detects the telltale dips in brightness caused when an alien planet crosses in front of, or transits, its star from Kepler's perspective. Kepler needs to witness three of these transits to firmly identify a planet candidate.

This technique has been extremely effective. In just its first four months of operation, Kepler discovered 1,235 exoplanet candidates. So far, two dozen of them have been confirmed by follow-up observations — including Kepler-16b, a world with two suns that was announced recently.Kepler team members have estimated that 80 percent or so of the telescope's candidates will probably end up being the real deal. If that's the case, Kepler's finds to date would more than double the number of known alien planets, which currently stands at about 685.

"What we're seeing is this trend — the smaller the planet, the more of them there are," Sobeck told Space.com. "That's great news for the idea of finding Earth-like planets, or Earth-size planets. Once you have Earth-size planets, all it has to do is be in the right orbit, and it's habitable."

We've come to expect the unexpected," said Sara Seager, a Massachusetts Institute of Technology exoplanet specialist also on the Kepler science team. So, who knows what 2012 may bring.

As Arthur C. Clarke, physicist and author of 2001: A Space Odyssey wrote, "The idea that we are the only intelligent creatures in a cosmos of a hundred billion galaxies is so preposterous that there are very few astronomers today who would take it seriously. It is safest to assume therefore, that they are out there and to consider the manner in which this may impinge upon human society."

                 

ALIEN PLANET