The Intelligent-Life Lottery

Almost 20 years ago, in the pages of an obscure publication called Bioastronomy News, two giants in the world of science argued over whether SETI — the Search for Extraterrestrial Intelligence — had a chance of succeeding. Carl Sagan, as eloquent as ever, gave his standard answer. With billions of stars in our galaxy, there must be other civilizations capable of transmitting electromagnetic waves. By scouring the sky with radio telescopes, we just might intercept a signal.

But Sagan’s opponent, the great evolutionary biologist Ernst Mayr, thought the chances were close to zero. Against Sagan’s stellar billions, he posed his own astronomical numbers: Of the billions of species that have lived and died since life began, only one — Homo sapiens — had developed a science, a technology, and the curiosity to explore the stars. And that took about 3.5 billion years of evolution. High intelligence, Mayr concluded, must be extremely rare, here or anywhere. Earth’s most abundant life form is unicellular slime.

Since the debate with Sagan, more than 1,700 planets have been discovered beyond the solar system — 700 just this year. Astronomers recently estimated that one of every five sunlike stars in the Milky Way might be orbited by a world capable of supporting some kind of life.

That is about 40 billion potential habitats. But Mayr, who died in 2005 at the age of 100, probably wouldn’t have been impressed. By his reckoning, the odds would still be very low for anything much beyond slime worlds. No evidence has yet emerged to prove him wrong.

Maybe we’re just not looking hard enough. Since SETI began in the early 1960s, it has struggled for the money it takes to monitor even a fraction of the sky. In an online essay for The Conversation last week, Seth Shostak, the senior astronomer at the SETI Institute, lamented how little has been allocated for the quest — just a fraction of NASA’s budget.

“If you don’t ante up,” he wrote, “you will never win the jackpot. And that is a question of will.”

Three years ago, SETI’s Allen Telescope Array in Northern California ran out of money and was closed for a while. Earlier this month, it was threatened by wildfire — another reminder of the precariousness of the search.

It has been more than 3.5 billion years since the first simple cells arose, and it took another billion years or so for some of them to evolve and join symbiotically into primitive multicellular organisms. These biochemical hives, through random mutations and the blind explorations of evolution, eventually led to creatures with the ability to remember, to anticipate and — at least in the case of humans — to wonder what it is all about.

Every step was a matter of happenstance, like the arbitrary combination of numbers — 3, 12, 31, 34, 51 and 24 — that qualified a Powerball winner for a $90 million prize this month. Some unknowing soul happened to enter a convenience store in Rifle, Colo., and — maybe with change from buying gasoline or a microwaved burrito — purchase a ticket just as the machine was about to spit out those particular numbers.

According to the Powerball website, the chance of winning the grand prize is about one in 175 million. The emergence of humanlike intelligence, as Mayr saw it, was about as likely as if a Powerball winner kept buying tickets and — round after round — hit a bigger jackpot each time. One unlikelihood is piled on another, yielding a vanishingly rare event.

In one of my favorite books, “Wonderful Life,” Stephen Jay Gouldcelebrated what he saw as the unlikelihood of our existence. Going further than Mayr, he ventured that if a slithering creature calledPikaia gracilens had not survived the Cambrian extinction, about half a billion years ago, the entire phylum called Chordata, which includes us vertebrates, might never have existed.

Gould took his title from the Frank Capra movie in which George Bailey gets to see what the world might have been like without him — idyllic Bedford Falls is replaced by a bleak, Dickensian Pottersville.

For Gould, the fact that any of our ancestral species might easily have been nipped in the bud should fill us “with a new kind of amazement” and “a frisson for the improbability of the event” — a fellow agnostic’s version of an epiphany.

“We came this close (put your thumb about a millimeter away from your index finger), thousands and thousands of times, to erasure by the veering of history down another sensible channel,” he wrote. “Replay the tape a million times,” he proposed, “and I doubt that anything like Homo sapiens would ever evolve again. It is, indeed, a wonderful life.”

Other biologists have disputed Gould’s conclusion. In the course of evolution, eyes and multicellularity arose independently a number of times. So why not vertebrae, spinal cords and brains? The more bags of tricks an organism has at its disposal, the greater its survival power may be. A biological arms race ensues, with complexity ratcheted ever higher.

But those occasions are rare. Most organisms, as Daniel Dennett put it in “Darwin’s Dangerous Idea,” seem to have “hit upon a relatively simple solution to life’s problems at the outset and, having nailed it a billion years ago, have had nothing much to do in the way of design work ever since.” Our appreciation of complexity, he wrote, “may well be just an aesthetic preference.”

In “Five Billion Years of Solitude,” by Lee Billings, published last year, the author visited Frank Drake, one of the SETI pioneers.

“Right now, there could well be messages from the stars flying right through this room,” Dr. Drake told him. “Through you and me. And if we had the right receiver set up properly, we could detect them. I still get chills thinking about it.”

He knew the odds of tuning in — at just the right frequency at the right place and time — were slim. But that just meant we needed to expand the search.

“We’ve been playing the lottery only using a few tickets,” he said.

Study Reveals Immune System is Dazed and Confused During Spaceflight

There is nothing like a head cold to make us feel a little dazed. We get things like colds and the flu because of changes in our immune system. Researchers have a good idea what causes immune system changes on Earth—think stress, inadequate sleep and improper nutrition. But the results of two NASA collaborative investigations—Validation of Procedures for Monitoring Crewmember Immune Function (Integrated Immune) and Clinical Nutrition Assessment of ISS Astronauts, SMO-016E (Clinical Nutrition Assessment)—recently published in the Journal of Interferon & Cytokine Research suggest that spaceflight may temporarily alter the immune system of crew members flying long duration missions aboard the International Space Station. This is of concern as NASA looks ahead to six-month and multiple-year missions to asteroids, the moon and Mars because something as simple as a cold or the flu can be risky business in space.

Data generated early in NASA’s Integrated Immune study indicated that the distribution of immune cells in the blood of crew members aboard the space station is relatively unchanged during flight. However, they also revealed that some cell function is significantly lower than normal, or depressed, and some cell activity is heightened. In a sense, the immune systems of crew members are confused.

When cell activity is depressed, the immune system is not generating appropriate responses to threats. This may also lead to the asymptomatic viral shedding observed in some crew members, which means latent, or dormant, viruses in the body reawaken, but without symptoms of illness. When activity heightens, the immune system reacts excessively, resulting in things like increased allergy symptoms and persistent rashes, which have been reported by some crew members.

“Prior to the Integrated Immune study, little immune system in-flight data had been collected,” said Brian Crucian, Ph.D. and NASA biological studies and immunology expert. “Previous post-flight studies were not enough to make any determination about spaceflight’s effect on the immune system. This in-flight data provided the information we needed to determine that immune dysregulation does occur and actually persists during long-duration spaceflight.”

European Space Agency astronaut Andre Kuipers, Expedition 30 flight engineer, prepares vials in the Columbus laboratory of the International Space Station for venous blood sample draws during an immune system investigation.

Recently, in a collaboration between NASA’s Integrated Immune and Clinical Nutrition Assessment flight studies, researchers examined the blood plasma of 28 crew members before, during and after their missions. They were measuring for the concentration of cytokines – the proteins that regulate immunity. Cytokines recruit immune cells to the infected or injured body site, facilitate cell-to-cell communication, and signal immune cells to activate and mount a defense against invaders. This process is usually referred to as inflammation. The data indicated that, like the changes in cell function indicated in the Integrated Immune study, crew members also have changes in blood cytokines that persist during flight. This gives researchers an idea of what areas of a crew member’s immune system may be confused during flight.

According to Crucian, the immune system is likely being altered by many factors associated with the overall spaceflight environment. “Things like radiation, microbes, stress, microgravity, altered sleep cycles and isolation could all have an effect on crew member immune systems,” said Crucian. “If this situation persisted for longer deep space missions, it could possibly increase risk of infection, hypersensitivity, or autoimmune issues for exploration astronauts.”

Despite these immune system changes, it has yet to be determined whether these alterations increase crew risk for medical issues during spaceflight. According to Crucian, further investigations are required to precisely assess whether there is increased clinical risk to crew members on longer duration missions.

NASA Human Research Program Chief Scientist Mark Shelhamer says continued study of the immune system is critical. “These studies tell us that this is an important issue and that we are measuring the right things,” said Shelhamer. “They also tell us there is no place during spaceflight where we see stabilization of the immune system. This is critical as we pursue longer duration missions and why we are studying this further during the upcoming one-year mission.”

Once these investigations are complete, Crucian expects the agency will have a decision point for establishing countermeasures that it must then decide how to implement. If deemed necessary, countermeasures for immunity could include new types of radiation shielding, nutritional supplementation, pharmaceuticals and more.

Studies of how space flight affects the immune system may provide benefits to Earth-based medicine. This includes information on how stress causes immune system changes in healthy adults, changes that may precede disease.

In the end, NASA may just shift the immune system during spaceflight from dazed to unfazed.

Fascinating rhythm: Light pulses illuminate a rare black hole

The universe has so many black holes that it's impossible to count them all. There may be 100 million of these intriguing astral objects in our galaxy alone. Nearly all black holes fall into one of two classes: big, and colossal. Astronomers know that black holes ranging from about 10 times to 100 times the mass of our sun are the remnants of dying stars, and that supermassive black holes, more than a million times the mass of the sun, inhabit the centers of most galaxies.

But scattered across the universe like oases in a desert are a few apparent black holes of a more mysterious type. Ranging from a hundred times to a few hundred thousand times the sun's mass, these intermediate-mass black holes are so hard to measure that even their existence is sometimes disputed. Little is known about how they form. And some astronomers question whether they behave like other black holes.

Now a team of astronomers has accurately measured—and thus confirmed the existence of—a black hole about 400 times the mass of our sun in a galaxy 12 million light years from Earth. The finding, by University of Maryland astronomy graduate student Dheeraj Pasham and two colleagues, was published online August 17 in the journal Nature.

Co-author Richard Mushotzky, a UMD astronomy professor, says the black hole in question is a just-right-sized version of this class of astral objects.

"Objects in this range are the least expected of all black holes," says Mushotzky. "Astronomers have been asking, do these objects exist or do they not exist? What are their properties? Until now we have not had the data to answer these questions." While the intermediate-mass black hole that the team studied is not the first one measured, it is the first one so precisely measured, Mushotzky says, "establishing it as a compelling example of this class of black holes."

A black hole is a region in space containing a mass so dense that not even light can escape its gravity. Black holes are invisible, but astronomers can find them by tracking their gravitational pull on other objects. Matter being pulled into a black hole gathers around it like storm debris circling a tornado's center. As this cosmic stuff rubs together it produces friction and light, making black holes among the universe's brightest objects.

Since the 1970s astronomers have observed a few hundred objects that they thought were intermediate-mass black holes. But they couldn't measure their mass, so they couldn't be certain. "For reasons that are very hard to understand, these objects have resisted standard measurement techniques," says Mushotzky.

Pasham, who will receive his Ph.D. in astronomy at UMD August 22, focused on one object in Messier 82, a galaxy in the constellation Ursa Major. Messier 82 is our closest "starburst galaxy," where young stars are forming. Beginning in 1999 a NASA satellite telescope, the Chandra X-ray Observatory, detected X-rays in Messier 82 from a bright object prosaically dubbed M82 X-1. Astronomers, including Mushotzky and co-author Tod Strohmayer of NASA's Goddard Space Flight Center, suspected for about a decade that the object was an intermediate-mass black hole, but estimates of its mass were not definitive enough to confirm that.

Between 2004 and 2010 NASA's Rossi X-Ray Timing Explorer (RXTE) satellite telescope observed M82 X-1 about 800 times, recording individual x-ray particles emitted by the object. Pasham mapped the intensity and wavelength of x-rays in each sequence, then stitched the sequences together and analyzed the result.

Among the material circling the suspected black hole, he spotted two repeating flares of light. The flares showed a rhythmic pattern of light pulses, one occurring 5.1 times per second and the other 3.3 times per second – or a ratio of 3:2.

The two light oscillations were like two dust motes stuck in the grooves of a vinyl record spinning on a turntable, says Mushotzky. If the oscillations were musical beats, they would produce a specific syncopated rhythm. Think of a Latin-inflected bossa nova, or a tune from The Beatles' Abbey Road:

"Mean Mister Mustard sleeps in the park, shaves in the dark, try'na save paper."

In music, this is a 3:2 beat. Astronomers can use a 3:2 oscillation of light to measure a black hole's mass. The technique has been used on smaller black holes, but it has never before been applied to intermediate-mass black holes.

Pasham used the oscillations to estimate that M82 X-1 is 428 times the mass of the sun, give or take 105 solar masses. He does not propose an explanation for how this class of black holes formed. "We needed to confirm their existence observationally first," he says. "Now the theorists can get to work."

Though the Rossi telescope is no longer operational, NASA plans to launch a new X-ray telescope, the Neutron Star Interior Composition Explorer (NICER), in about two years. Pasham, who will begin a post-doctoral research position at NASA Goddard in late August, has identified six potential intermediate-mass black holes that NICER might explore.

This work is based on observations made with the Rossi X-ray Timing Explorer (RXTE), managed and controlled by NASA's Goddard Space Flight Center in Greenbelt, Md. The content of this article does not necessarily reflect the views of NASA or Goddard Space Flight Center.

Blockfall on the North Polar Layered Deposits

The North Polar layered deposits (NPLD) are a stack of layers of ice and dust at the North Pole of Mars. The layers are thought to have been deposited over millions of years, as the atmosphere changed in response to the varying tilt of the planet’s axis. Learning to read this record could tell us much about recent conditions on Mars, but we first need to understand the processes that have shaped the NPLD. 

Comparing this HiRISE image with an observation from the previous Martian year reveals an example of one of these processes: block falls. The slope is steep and fractured here, and a large chunk of dusty ice has tumbled down the slope and broken apart. Scientists on the HiRISE team are studying this process at many locations in order to measure how quickly the NPLD is changing. 

Other changes are visible on the slope as well: sand patches have shifted, and in some places on the slope they have been eroded into grooves or troughs, most likely by the carbon dioxide frost (dry ice) that covers the North Pole in the winter.

What Are These Mysterious Green Lights Photographed From the Space Station?

Bangkok is the bright city. The green lights outside the city? No idea…” This was the description tweeted astronaut by Reid Wiseman. So, what are those acid-green blotches scattered throughout the darkness of the Gulf of Thailand? 

The offshore illumination comes from fishing boats, which use enormous arrays of bright green LED lights to attract squid and plankton to the surface. 

“Bangkok is the bright city. The green lights outside the city? No idea…” This was the description accompanying the photo above, perplexingly Tweeted by Expedition 40/41 astronaut Reid Wiseman on Aug. 18, 2014. And while we’ve all seen fascinating photos of our planet shared by ISS crew members over the years this one is quite interesting, to say the least. Yes, there’s the bright illumination of Bangkok’s city lights, along with some stars, moonlit cloud cover extending northeast and the fine line of airglow over the horizon, but what are those acid-green blotches scattered throughout the darkness of the Gulf of Thailand? Bioluminescent algal blooms? Secret gamma-ray test labs? Underwater alien bases? 

The answer, it turns out, actually is quite fishy.

The offshore illumination comes from fishing boats, which use enormous arrays of bright green LED lights to attract squid and plankton to the surface.

According to an an Oct. 2013 article on NASA’s Earth Observatory site by Michael Carlowicz, “…fishermen from South America and Southeastern Asia light up the ocean with powerful lamps that attract the plankton and fish species that the squid feed on. The squid follow their prey toward the surface, where they are easier for fishermen to catch with jigging lines. Squid boats can carry more than a hundred of these lamps, generating as much as 300 kilowatts of light per boat.”

This Martian Basin Shows Off Our Solar System’s Violent Past

An impact 4.1 billion years ago left quite a mark! A Mars Express photo from late 2013 shows craters in Hellas Basin on Mars, which was formed when the planets in our young Solar System were under intense bombardment

A Mars Express image of craters in Hellas Basin, an impact basin on Mars that is one of the biggest in the solar system

Did that impact 4.1 billion years ago ever leave a scar! Here, a Mars Express photo from late 2013 (and just highlighted now) shows off craters in Hellas Basin, which was formed when the planets in our young Solar System were under intense bombardment from leftover remnants.

But over time, wind and erosion on Mars have changed the nature of this basin, the German Space Agency explained.

“Over time, the interior of Hellas Planitia has been greatly altered by geological processes,” the German Space Agency stated.

“The wind has blown dust into the basin, glaciers and streams have transported and deposited sediment, and volcanoes have built up layers of low-viscosity lava on the floor of Hellas. Despite its exposure to erosion and coverage by deposits for a long period of time, it is the best-preserved large impact basin on Mars.”

Forget Space Travel: Build This Telescope

What does Seth Shostak's pie-in-the-sky, dream telescope look like? Hint: it's really, really big.

The first telescopes were toys, charming amusements. Sure, there were a few practical uses, such as observing distant ships coming into harbor. Doing so allowed merchants to hurry down to the docks ahead of their telescope-free competitors, and snag all the better goods. Military commanders occasionally found telescopes handy as well. And when they weren't being used for commerce or conflict, these simple devices were undoubtedly helpful for checking out the personal parameters of careless neighbors.

In 1609, Galileo turned a telescope skyward -- a move that no one else seems to have considered. His instruments had lenses about the size of a half-dollar coin, and magnifications that were only about 20 times. Their simple optics had more aberrations than Vlad the Impaler.

Today, you wouldn't give a kid a telescope this lousy, unless you're inspiring her to forsake science in favor of a more lucrative occupation, like starching shirts. But these low-grade constructions were good enough to see the bigger moons of Jupiter, the craters of the moon, and stars making up the Milky Way. They were, despite their pitiful specifications, arguably the most important astronomical telescopes of all time.

Modern researchers would find Galileo's 'scopes useful only for batting Whiffle balls. They've moved on to bigger and better, and today are building some truly impressive instruments: a new generation of titanic telescopes that sport primary mirrors larger than tennis courts. These will snag a million times as much light as Galileo's instrument, which is really the motivation for their construction. But, thanks to an ability to undo a lot of the distortions caused by Earth's shuddering atmosphere, these new outsized 'scopes will be about as hawkeyed as the famed Hubble instrument -- able to see detail at a level of about 0.1 seconds of arc. That's enough to just make out a dime a dozen miles away.

Impressive, yes, but no one cares about examining far-off dimes. What about inspecting worlds around other stars, the so-called exoplanets that dominate a lot of astronomy news these days? Well, with these new giant telescopes, any Earth-size exoplanet would be smaller than one pixel in size. It would be a thoroughly unresolved pinpoint of light.

Useful, but not entirely gratifying.

I think it's fair to say that, given your 'druthers, you'd want an instrument that could map exoplanets in the kind of detail you get with Google Earth, with enough resolution to actually see the Great Wall of the Klingons, in case they've built one.

Could we construct such a telescope ... ever?

Here's what it takes: Let's assume that all the alien worlds you wish to view up close and personal are no more than 100 light-years away. That might sound pretty cramped to astronomy nerds, but there are probably several hundred thousand planets within that distance - enough to gratify even the most spirited voyeur.

At 100 light-years, something the size of a Honda Accord -- which I propose as a standard imaging test object -- subtends an angle of a half-trillionth of a second of arc. In case that number doesn't speak to you, it's roughly the apparent size of a cellnucleus on Pluto, as viewed from Earth.

You will not be stunned to hear that resolving something that minuscule requires a telescope with a honking size. At ordinary optical wavelengths, "honking" works out to a mirror 100 million miles across. You could nicely fit a reflector that large between the orbits of Mercury and Mars. Big, yes, but it would permit you to examine exoplanets in incredible detail.

The down side is obvious: Who could ever construct such a thing? Well, fortunately, no one has to. Instead, you could field a phalanx of small mirrors in space, spread outover 100 million miles. They wouldn't even have to maintain a fixed pattern, as long as you could accurately keep track of their relative positions.

No huge mirror: just a manageable number of small ones. The ability to see detail would be the same. And, of course, it's a heck of a lot easier to turn an array of small instruments to different places on the sky than to pivot a 100 million-mile monstrosity.

Of course, there are a few small problems of principle here. You need to collect enough light to make the imaging possible, and correct for the fact that the target exoplanet is both rotating and sliding across the sky. Both problems can be dealt with, at least in theory -- which suggests that they can also be dealt with in practice, given sufficient effort.

But think of the implications. There's a lot of talk about interstellar travel, and whether we will ever be capable of rocketing to other stars. It's a tough thing to do.

However, if the type of telescope described here can be built, then the tyranny of distance is vanquished. You can forget deep space probes and their long travel times. We could explore alien worlds in the comfort of our own homes, as our laptops scroll and zoom through data sets collected by a mammoth, space-based telescope array.

It would also, quite obviously, be a whole new way to search for extraterrestrial life ... just look for it, or its artifacts (like cities).

This is, to my mind, the ultimate telescope. It's not for our generation to build, or even the next two. But after that ...?

In the Center of the Lagoon Nebula

The center of the Lagoon Nebula is a whirlwind of spectacular star formation. Visible near the image center, at least two long funnel-shaped clouds, each roughly half a light-year long, have been formed by extreme stellar winds and intense energetic starlight. This picture, spanning about 5 light years, combines images taken by the orbiting Hubble Space Telescope. 

Explanation: The center of the Lagoon Nebula is a whirlwind of spectacular star formation. Visible near the image center, at least two long funnel-shaped clouds, each roughly half a light-year long, have been formed by extreme stellar winds and intense energetic starlight. The tremendously bright nearby star, Herschel 36, lights the area. Walls of dust hide and redden other hot young stars. As energy from these stars pours into the cool dust and gas, large temperature differences in adjoining regions can be created generating shearing winds which may cause the funnels. This picture, spanning about 5 light years, combines images taken by the orbiting Hubble Space Telescope. The Lagoon Nebula, also known as M8, lies about 5,000 light years distant toward the constellation of Sagittarius.

Eastern Mediterranean Coastline at Night

This night photograph taken by astronauts aboard the International Space Station (ISS) shows the location and size of cities at the east end of the Mediterranean Sea. The largest, brightest cluster is the Israeli city of Tel Aviv, a port set against the blackness of the Mediterranean Sea. Jerusalem, Israel’s capital city, and Amman, Jordan’s capital, are the next largest (with Amman’s lights having a whiter tone),

Bright but narrow lines that snake between the cities are highways. The darker areas with smaller patches of lights are mostly agricultural and pastoral areas of Israel, Sinai, the West Bank, and Jordan. A wide, almost black zone between Jerusalem and Amman trends north-south across the right half of the image; it is the long valley that includes the Jordan River and the Dead Sea.

Astronaut photograph ISS040-E-74022 was acquired on July 22, 2014, with a Nikon D3S digital camera using an 85 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by the Expedition 40 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. 

A spectacular landscape of star formation

A new image shows two dramatic star formation regions in the southern Milky Way. The first is of these, on the left, is dominated by the star cluster NGC 3603, located 20,000 light-years away, in the Carina–Sagittarius spiral arm of the Milky Way galaxy. The second object, on the right, is a collection of glowing gas clouds known as NGC 3576 that lies only about half as far from Earth. 

This mosaic of images from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile shows two dramatic star formation regions in the southern Milky Way. The first of these, on the left, is dominated by the star cluster NGC 3603, located about 20 000 light-years away, in the Carina-Sagittarius spiral arm of the Milky Way galaxy. The second object, on the right, is a collection of glowing gas clouds known as NGC 3576 that lies only about half as far from Earth.

Date:

August 20, 2014

Source:

European Southern Observatory - ESO

Summary:

A new image shows two dramatic star formation regions in the southern Milky Way. The first is of these, on the left, is dominated by the star cluster NGC 3603, located 20,000 light-years away, in the Carina–Sagittarius spiral arm of the Milky Way galaxy. The second object, on the right, is a collection of glowing gas clouds known as NGC 3576 that lies only about half as far from Earth.

THIS This image, captured by the Wide Field Imager at ESO's La Silla Observatory in Chile, shows two dramatic star formation regions in the southern Milky Way. The first is of these, on the left, is dominated by the star cluster NGC 3603, located 20,000 light-years away, in the Carina-Sagittarius spiral arm of the Milky Way galaxy. The second object, on the right, is a collection of glowing gas clouds known as NGC 3576 that lies only about half as far from Earth.

NGC 3603 is a very bright star cluster and is famed for having the highest concentration of massive stars that have been discovered in our galaxy so far. At the centre lies a Wolf-Rayet multiple star system, known as HD 97950. Wolf-Rayet stars are at an advanced stage of stellar evolution, and start off with around 20 times the mass of the Sun. But, despite this large mass, Wolf-Rayet stars shed a considerable amount of their matter due to intense stellar winds, which blast the star's surface material off into space at several million kilometres per hour, a crash diet of cosmic proportions.

NGC 3603 is in an area of very active star formation. Stars are born in dark and dusty regions of space, largely hidden from view. But as the very young stars gradually start to shine and clear away their surrounding cocoons of material they become visible and create glowing clouds in the surrounding material, known as HII regions. HII regions shine because of the interaction of ultraviolet radiation given off by the brilliant hot young stars with the hydrogen gas clouds. HII regions can measure several hundred light-years in diameter, and the one surrounding NGC 3603 has the distinction of being the most massive in our galaxy.

The cluster was first observed by John Herschel on 14 March 1834 during his three-year expedition to systematically survey the southern skies from near Cape Town. He described it as a remarkable object and thought that it might be a globular star cluster. Future studies showed that it is not an old globular, but a young open cluster, one of the richest known.

NGC 3576, on the right of the image, also lies in the Carina-Sagittarius spiral arm of the Milky Way. But it is located only about 9000 light-years from Earth -- much closer than NGC 3603, but appearing next to it in the sky.

NGC 3576 is notable for two huge curved objects resembling the curled horns of a ram. These odd filaments are the result of stellar winds from the hot, young stars within the central regions of the nebula, which have blown the dust and gas outwards across a hundred light-years. Two dark silhouetted areas known as Bok globules are also visible in this vast complex of nebulae. These black clouds near the top of the nebula also offer potential sites for the future formation of new stars.

NGC 3576 was also discovered by John Herschel in 1834, making it a particularly productive and visually rewarding year for the English astronomer.

Dust reveals ancient origin for Saturn's rings

Dust reveals ancient origin for Saturn's rings. New data from the Cassini spacecraft suggests rings were formed 4.4 billion years ago - making the rings 3x to 10x older than previously thought. Learn more here:

Saturn's iconic rings seem to have formed early in the planet's history.

Saturn’s spectacular ring system may date back some 4.4 billion years to the time when the planet itself formed, new findings suggest. The work could help to resolve a long-running debate about whether the rings are ancient or formed much more recently, on the order of hundreds of millions of years ago.


For the first time, NASA's Cassini spacecraft has measured the rate at which dust from outside the Saturn system is falling on the rings and polluting them. That rate turns out to be about 40 times lower than previously thought, which eliminates a major argument against the ‘old rings’ theory: that if the rings had been around for billions of years, they should have gotten coated with a dark spray of other particles and look a lot dirtier than they do.

"The rings can be three to ten times older than we used to think," says Larry Esposito, a planetary scientist at the University of Colorado Boulder.

Rare dusting

Cassini has been orbiting Saturn since 2004, but only now has its cosmic-dust instrument managed to gather enough examples of dust particles that have entered the Saturn system and fallen on its rings. Sascha Kempf, a space physicist also at the University of Colorado, presented the latest (and long-anticipated) data during a workshop at the university on 15 August.

Over the course of seven years, Kempf and his colleagues detected just 140 particles whose trajectories show that they must have come from elsewhere in the Solar System, and which were large enough to have dirtied the rings.

Researchers had expected to see a lot more than just 20 of these particles per year, but that is because they were estimating dust flux using data from the inner Solar System, Kempf says. The Cassini data show that there is a lot less dust out by Saturn, and the particles all seem to come from the distant region of space known as the Kuiper belt, where icy bodies such as Pluto exist. “We’re seeing very, very different stuff,” Kempf says.

The lower rate of particle flux suggests that Saturn’s rings could be ancient after all. “If the pollution problem is not as severe, then the rings could last a lot longer before they turn black,” says Phillip Nicholson, a planetary scientist at Cornell University in Ithaca, New York.

There are still other arguments for why Saturn’s rings could be young, such as the possibility that the rings formed later from the remains of moons that were gravitationally ripped apart. “But I’m more inclined to believe the old-rings model now than before,” says Jeff Cuzzi, a planetary scientist at NASA’s Ames Research Center in Moffett Field, California.

Other factors might also have reshaped the ring system over time. Cuzzi notes that there could have been more dust in the early days of the Solar System than there is today. The rings might also undergo some kind of constant recycling that keeps them looking relatively fresh, says Esposito.

Cassini mission planners have still not heard the results of a NASA ‘senior review’ that will determine funding for planetary missions beyond September. But they are expecting to fly the craft until 2017, when Cassini will perform a series of spectacular loops between the ring system and the planet itself. In its final months, the spacecraft will measure the mass of the rings directly for the first time, before plunging into Saturn’s atmosphere in a grand finale.

Spot ET's waste heat for chance to find alien life

Rather than searching for aliens phoning home, scientists are looking for signs of the homes themselves. SETI Institute's Franck Marchis weighs in on why this new tactic of searching is so intriguing.

RATHER than searching for aliens phoning home, scientists are looking for signs of the homes themselves. A new project proposing that galaxy-spanning alien civilisations should generate detectable heat has turned up a few dozen galaxies that hold promise as harbours for life.

The best-known technique used to search for tech-savvy aliens iseavesdropping on their communications with each other. But this approach assumes ET is chatty in channels we can hear.

The new approach, dubbed G-HAT for Glimpsing Heat from Alien Technologies, makes no assumptions about what alien civilisations may be like.

"This approach is very different," says Franck Marchis at the SETI Institute in California, who was not involved in the project. "I like it because it doesn't put any constraints on the origin of the civilisation or their willingness to communicate."

Instead, it utilises the laws of thermodynamics. All machines and living things give off heat, and that heat is visible as infrared radiation. The G-HAT team combed through the catalogue of images generated by the Wide-field Infrared Survey Explorer, or WISE, which released an infrared map of the entire sky in 2012. A galaxy should emit about 10 per cent of its light in the mid-infrared range, says team leader Jason Wright at Pennsylvania State University. If it gives off much more, it could be being warmed by vast networks of alien technology – though it could also be a sign of more prosaic processes, such as rapid star formation or an actively feeding black hole at the galaxy's centre.

The team's preliminary survey suggests that such galaxies are rare, but they are out there. "We have found several dozen galaxies giving out a superlative amount of mid-infrared light," says Wright. About 50 of these are emitting more than half of their starlight in the mid-infrared, the team reports (Astrophysical Journal, doi.org/t82).

Could that mean we have already found alien civilisations that have spread across galaxies?

"If by 'found them' you mean that WISE detected the waste heat from them, then yes, that's right – if these sorts of energy-hungry civilisations exist, WISE should have detected them," Wright says. But identifying them is another story. "Distinguishing that waste heat from ordinary astrophysical dust will be very difficult in many cases, and proving it's of alien origin will be even harder," he says.

The next step is to look at the stars and galaxies that raised the infrared flag in the WISE survey and figure out if there are more ordinary processes at work.

"This effort is important because it tries to resolve the question of extraterrestrial life scientifically, using the laws of chemistry and physics that govern the universe," says astronomer Geoff Marcy of the University of California, Berkeley.

Even if the effort doesn't discover intelligent aliens, it is still doing solid science, says Marchis. "This work is useful no matter what because it's cataloguing the mid-infrared of our stars and galaxies," he says. "Like our exoplanet search and using rovers to look for microbes on Mars, this search for extraterrestrial life is driving useful science."

Ring Nebula

Though the Ring Nebula (M57) can be spotted with a small telescope, it took collaborative effort combining data from three different large telescopes to produce this image. This composite image includes narrowband hydrogen image, visible light emission, and infrared light emission. 

Explanation: It is a familiar sight to sky enthusiasts with even a small telescope. There is much more to the Ring Nebula (M57), however, than can be seen through a small telescope. The easily visible central ring is about one light-year across, but this remarkably deep exposure - a collaborative effort combining data from three different large telescopes - explores the looping filaments of glowing gas extending much farther from the nebula's central star. This remarkable composite image includes narrowband hydrogen image, visible light emission, and infrared light emission. Of course, in this well-studied example of a planetary nebula, the glowing material does not come from planets. Instead, the gaseous shroud represents outer layers expelled from a dying, sun-like star. The Ring Nebula is about 2,000 light-years away toward the musical constellation Lyra.