In 1995, astronomer Bob Williams wanted to point the Hubble Space Telescope at a patch of sky filled with absolutely nothing remarkable. For 100 hours.
It was a terrible idea, his colleagues told him, and a waste of valuable telescope time. People would kill for that amount of time with the sharpest tool in the shed, they said, and besides — no way would the distant galaxies Williams hoped to see be bright enough for Hubble to detect.
Plus, another Hubble failure would be a public relations nightmare. Perceptions of the project, which had already cost multiple billions of dollars, were pretty dismal. Not much earlier, astronauts had dragged Hubble into the cargo bay of the space shuttle Endeavour and corrected a disastrous flaw in the prized telescope’s vision. After the fix, the previously blind eye in the sky could finally see stars as more than blurred points of light. And now, finally, it was time to start erasing the frustrations of Hubble’s early years.
Except that staring at nothing and coming up empty didn’t seem like the best way to do that.
But Williams was undeterred. And, to be honest, it didn’t really matter how much his colleagues protested. As director of the Space Telescope Science Institute, he had a certain amount of Hubble’s time at his personal disposal. “The telescope allocation committee would never have approved such a long, risky project,” he explains. “But as director, I had 10 percent of the telescope time, and I could do what I wanted.”
Wiliams suspected the billion light-year stare might capture eons of galactic evolution in a single frame and uncover some of the faintest, farthest galaxies ever seen. And to him, the potential observations were so important and so fundamental for understanding how the universe evolved that the experiment was a no-brainer, consequences be damned.
“Scientific discovery requires risk,” Williams says. “And I was at a point in my career where I said, “If it’s that bad, I’ll resign. I‘ll fall on my sword.’”
So, with his job perhaps on the line, Williams went off, put together a small team of post-docs, and did exactly as he’d planned. For 100 hours, between Dec. 18 and 28, Hubble stared at a patch of sky near the Big Dipper’s handle that was only about 1/30th as wide as the full moon. In total, the telescope took 342 pictures of the region, each of which was exposed for between 25 and 45 minutes. The images were processed and combined, then colored, and 17 days later, released to the public.
It turned out that “nothing” was actually stuffed with of galaxies. More than 3,000 of them came spilling out, some roughly 12 billion years old. Spiral, elliptical, irregular – red, white, blue, and yellow – the smudges of light that leapt from the final composite image cracked the universe in ways scientists never could have imagined.
“With this achievement, the estimated number of galaxies in the universe had multiplied enormously — to 50 billion, five times more than previously expected,” wrote John Noble Wilford in The New York Times. And some of the older galaxies – those distant, faint ones that were supposedly impossible for Hubble to see – looked really, really different.
“When the galaxies were young, they were very irregular — they were having collisions, they were erupting, they were having adolescent outbursts,” says Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics. He was among the scientists who initially thought the deep field was a bad idea. “Bob was right, I was wrong. The use of that discretionary time was a courageous thing,” he says.
But there was more. Williams had gotten in touch with astronomers at the Keck telescopes in Hawaii ahead of time and asked them to point their Earth-based guns at the same patch of sky. Together, the observations helped astronomers develop something of a shortcut for determining cosmological distances to these galaxies, unlocking large portions of the universe.
As for public relations? The image now known as the Hubble Deep Field captivated pretty much everyone. To say it was a triumph would be an understatement. “The nerve that it took to say, ‘We’re going to point where there isn’t anything,’ was interesting,” says John Mather, a Nobel Laureate and senior project scientist for the James Webb Space Telescope. “And Bob Williams got a lot of nice recognition for that leadership.”
Not long after, Williams’ experiment was repeated in a different patch of sky in the southern constellation Tucana, and came to be called the Hubble Deep Field South. In 2004, a million-second exposure of nothing produced the Hubble Ultra Deep Field, filled with even more galaxies than the original. And in 2012, combining 10 years of Ultra Deep Field exposures produced the Hubble eXtreme Deep Field.
These images have offered “a glimpse of the hundreds of billions of galaxies that fill the universe,” says Hubble senior scientist Jennifer Wiseman, of NASA’s Goddard Space Flight Center. “That gives me and many people pause to be quiet and contemplate this majestic universe we live in, and be grateful we have a chance to look at it.”
Jason Kalirai, project scientist with the Webb telescope, goes and step further and places the Hubble Deep Field in a rather impressive historical context. “One of the questions that even the earliest civilizations probably asked themselves is, ‘What is our place in the universe?'” There have been a few times in our history when the prevailing answer to that question has been overthrown, he says. Once was when Galileo turned his telescope to Jupiter and its moons and helped show that not everything revolves around the Earth; another was when the astronomer Edwin Hubble showed, in the early 1900s, that not every speck of light in the sky belongs to our own galaxy.
A third is the Hubble Deep Field. “It showed that the universe is teeming with these galaxies, and if you do a census of how many galaxies you see, and think about how many more are in the night sky, you can conclude that there are as many galaxies as there are stars in the Milky Way,” Kalirai says.
As for Williams? Well, he sums up the experience in a characteristically understated way: “It turned out to be a neat image. Really.”
Recently, NASA released some pretty spectacular footage captured by an astronaut wearing a GoPro camera while spacewalking around the International Space Station. In the videos, Earth slowly rotates below the space station while astronauts fiddle with cables, install antennae, and work on the robotic arm.
You can see both videos here (and we’ve included some screen grabs in the gallery above).
The astronaut wearing the camera is Terry Virts, and his fellow spacewalker is Barry “Butch” Wilmore. The team had stepped outside to reconfigure parts of the space station so future crewed spacecraft can dock. You can see some of the work they do in each of the two videos, which last for around an hour apiece. But the two extravehicular activities sent Virts and Wilmore into space for longer than six hours.
After sifting through the spacescapes, we were curious about a few things. For example, what’s the source of the sound in the videos? Sound waves can’t travel in a vacuum, but there’s a persistent humming and clanking accompanying both spacewalks. NASA’s spacewalk teams say they believe that is the sound of the spacesuit’s fan, which circulates air and also drives the water pump and water separator. “The camera was mounted to the mini-workstation which is mounted to the suit. So, the vibrations just carried through the system,” NASA spokesperson Dan Huot relayed.
We had some more questions about these videos, so we caught up with Huot, who’s based at NASA’s Johnson Space Center in Houston, Texas, and got a brief glimpse behind the scenes.
NG: First, what’s going on in each of the two videos?
Dan Huot: The first spacewalk, EVA 30, was on February 25th. It was the second in a series of three that the pair of them — Terry Virts and Butch Wilmore – did. Terry had the camera in both. They finished routing a bunch of cables, a little over 360 feet of cabling, and got it tied down and connected. Those cables provide power and data to one of the new docking adapters that’s going to make its way up there. Terry Virts had to apply some grease to a couple of parts inside the robotic arm, and that’s what a lot of the first video shows.
EVA 31, on March 1, was the same two guys. They installed two new metal antennae booms. They routed over 400 feet of cable to plug it all in. Those are for the new communication system those commercial vehicles are going to use to communicate with the station, get range data, help get their final rendezvous and docking information.
NG: What is that little spinning satellite dish in the first spacewalk doing?
Huot: That’s a device called RapidScat. It’s a scatterometer that measures wind speed and direction over the ocean, using radar pulses that are reflected from the ocean surface. It’s used for things like weather forecasting, monitoring hurricanes, and large-scale climate changes. It’s doing that all the time, and is a fairly recent addition, too – it just flew up there in the fall of 2014.
NG: What other fun instruments can we see?
Huot: In EVA 30, Terry Virts actually spends quite a bit of time looking at a big circle that’s basically the business end of the space station’s robotic arm. It’s called Canadarm 2 and it basically built the space station. It’s used for moving around modules and moving around people – they can lock their feet to the end of it and ride it around during spacewalks. He had to go in and apply a bunch of grease to some of the internal components because they were starting to show some wear.
NG: How often do astronauts go on spacewalks?
Huot: It’s pretty varied. They do them whenever there’s an emergency reason – every once in a while, stuff breaks and they have to go out and replace a part or fix something. That’s happened quite a few times in the last couple of years.
This year, they had the three planned walks at the end of February and beginning of March. There are four more planned throughout the rest of the year. The number varies a lot year-to-year because we’re not really building the station anymore. When we were building the station, we would have dozens in a given year.
In history, there’s been 187 spacewalks in total – both U.S. and Russian spacewalks.
NG: What will happen during the other spacewalks this year?
Huot: They’re actually going to be continuing the work from the walks these videos were taken from. We’re preparing the station for some new additions – like new docking adapters, two of them in the next year or so. The first will fly up this summer. So we have to do a spacewalk shortly after to get that installed.
These new docking adapters are for the new commercial crew vehicles.
NG: Can you tell me some more about those vehicles?
Huot: NASA contracted with two commercial companies, SpaceX and Boeing, to build crew vehicles. Since the shuttle program ended, we haven’t had a U.S. vehicle to bring men and women to the ISS. We’ve been relying on our Russian partners and their vehicles. At the end of last year, Boeing and SpaceX were each awarded a contract to develop a crewed vehicle, and they’re supposed to be flying to the space station with humans aboard in 2017. So we need to get these adaptors installed and make sure the station is ready.
NG: How long do spacewalks normally last?
Huot: Normally, between six and eight hours. That’s between six and eight hours, nonstop, for these guys. It’s actually one of the most exhausting things an astronaut can do. I think each of these spacewalks was right around the 6.5 hour mark.
NG: Who decides who gets to spacewalk?
Huot: Crew members are chosen based on proficiencies and the tasks they’ve trained for, how much spacewalking experience they already have. Like anything we do, there’s a lot of metrics that go into it. It’s not the astronauts pulling straws, saying well, “He went last time, I’m going to go this time.” The two guys who did these walks had trained for them on the ground a whole bunch of times.
NG: What kind of training had they done?
Huot: We have a facility called the Neutral Buoyancy Laboratory, and it’s this massive indoor pool about 40 feet deep and 200 feet long. We have a full-scale replica of the space station inside. All the astronauts will go there and they’ll train for these spacewalks. They’re able to choreograph and go through all these tasks down on the ground, so by the time they’re in space and it’s show time, they’ve already done it five or six times.
NG: How long are the training sessions?
Huot: They’re long, about eight hours plus prep time. They’ll simulate the entire spacewalk, and do it five or six times for each scenario.
NG: Why use the GoPros now?
Huot: The cameras are actually from our Russian colleagues; we don’t have any GoPros. So, they let us borrow them and take ‘em out. We don’t have any other capability yet to take an HD camera outside. The astronauts always have helmet cams, but they’re low-def, about 20 years old.
NG: Are there any plans to get GoPros and start sending them out in space?
Huot: I don’t know if it would be a GoPro or not, but we’ve been looking at it for a while, trying to get some type of high-def camera up there. Not only because it looks cool, but you can get engineering analysis video – there are a lot of advantages to getting higher-def video. And the rest of it is really cool-looking.
SEATTLE — Each January, thousands of astronomers get together and spend four days talking about stars, galaxies, planets, the cosmos, and everything in between. This year’s winter meeting of the American Astronomical Society was held in Seattle from Jan. 4-8, and it was so stuffed with science that I didn’t even get a glimpse of the city’s Space Needle…while covering a space conference.
Three time zones away, National Geographic’s Erika Engelhaupt and Dan Vergano worked overtime with me to bring you tales from the stars.
The meeting may have wrapped up, but we’re not done yet. We’ve got one more story in the works and have gotten word of some exciting announcements that will be arriving in the coming months. In the meantime, I’ve written these eight short meeting reports to share some more of the meeting’s celestial happenings, starting with that spectacularly star-studded image of the Andromeda Galaxy, above. (I’ve included a smattering of fun facts and other astronomical interestingness as well.)
Meeting Brief: A Hundred Million Stars
A new image of Earth’s nearest large galactic neighbor, the Andromeda Galaxy, is aglow with the light of more than 100 million stars. Scientists took long looks at a portion of the spiral galaxy’s disk, then published a panorama of 7,398 incredibly high-resolution Hubble Space Telescope images (above). In it, there are 1.5 billion pixels spanning 40,000 light-years. But the galaxyscape is more than just a pretty picture: It’s providing clues about Andromeda’s evolutionary history that teams are using to piece together how the galaxy formed and grew up. Among those clues are hints that Andromeda may have had a much more violent past than the Milky Way, and that older stars in its disk are behaving more erratically than younger stars.
Fun Fact: Scientists can now pinpoint Saturn’s exact location to within roughly one mile, by combining information from NASA’s Cassini spacecraft and NSF’s Very Long Baseline Array.
Meeting Brief: Hunting for Exomoons
If there’s one thing astronomers are learning about exoplanets, it’s that alien worlds are common throughout the galaxy. But planets aren’t the only things capable of supporting life. If those exoworlds are anything like the planets in our solar system, some of them have potentially habitable exomoons. “There are more habitable moons than there are planets in the cosmos,” says David Kipping of the Harvard-Smithsonian Center for Astrophysics. “Anyone who cares about the frequency of Earthlike worlds really can’t ignore this component.”
Kipping searches for exomoons hiding in the Kepler spacecraft’s data. It’s not easy; he first selects worlds that are capable of holding onto a moon, and for which a moon should be detectable. There are about 400 of those. But looking at each candidate world requires about 50,000 hours of processing time, he said at the meeting. So far, Kipping has searched for moons around 40 candidates and found nothing. This year, with upcoming time on NASA’s Pleiades supercomputer and a new computing cluster, he should be able to look at 300 more.
In other words, 2015 could be the year of the exomoon!
Fun Fact: Planetary debris disks can sometimes look like the Eye of Sauron.
Meeting Brief: Searching For Earth’s Twisted Sister
How common are Venus-like planets in the cosmos? That’s the question San Francisco State University astronomer Stephen Kane asked on Thursday, in one of the conference’s exoplanet sessions. While many scientists are focused on figuring out how common exo-Earths are, Kane points out that exo-Venuses could slip into those calculations.
“We know of at least one case where we can have two Earth-size planets with dramatically different atmospheres,” he says. “It behooves us to consider this very carefully when we’re looking at the planets in our sample.” Based on data from NASA’s Kepler spacecraft, Kane and his colleagues estimate that as any as 45 percent of (roughly) sunlike stars could host an exo-Venus. Smaller stars called M-dwarfs are slightly less likely to host these roasted worlds, and Kane suggests exo-Venuses might live around 30 percent of them.
Did You Know? Stars spin more slowly as they age, meaning that the rate at which a star spins should betray how old it is. But this has been a tricky relationship to parse, especially for stars that are cooler than the sun. Now, by measuring the frequency with which rotating star spots appear in a 2.5 billion-year-old cluster, astronomers are getting closer to developing a reliable stellar clock. (For more, see this report from Jonathan Webb at the BBC.)
Meeting Brief: Otherworldly Oceans, and a Recipe for Rocky Planets
Take two parts iron and oxygen, one part each of magnesium and silicon, add a handful of other ingredients, and shape into a sphere. Bake for several million years. Cool until a thin brown crust forms and the ball stops glowing. Then season with water and organic materials.
That’s the recipe astronomer Courtney Dressing figured out for cooking rocky planets – at least those that are 1.6 times Earth’s size and smaller. But, what about larger planets, the mega-Earths or mini-Neptunes? “Can we build them with the same recipe? Turns out, no,” says Dressing, of the Harvard-Smithsonian Institute for Astrophysics. “You can’t double the recipe that much. It doesn’t work.” Perhaps not surprisingly, bigger planets have different compositions. They’re a bit fluffier, a bit more gassy and icy. They’re also, says CfA astronomer Laura Schaefer, likely to have longer-lived oceans on their surfaces – a condition that is necessary for Life As We Know It. But there’s a catch: While oceans might live longer on super-Earths, they might also take longer to form. Conversely, Schaefer’s simulations show, oceans might live fast and die hard on planets smaller than Earth. “They outgas oceans very quickly,” Schaefer says.
Meeting Brief: Earth Isn’t Flat, But the Universe Is
The Universe is still flat – perhaps even flatter than Kansas, which is officially flatter than a pancake – according to the latest results from the Baryon Oscillation Spectroscopic Survey. The survey used sound waves from the early universe to plot the positions of 1.4 million galaxies and 300,000 quasars. Those positions, when combined with data from other projects, strongly confirm the existence of dark matter, says Harvard University’s Daniel Eisenstein, and point to a flat cosmology. What’s more, “Dark energy appears to be constant over time,” Eisenstein says. “The data has driven us back to the simplest case of a flat universe with a cosmological constant.”
For the briefest of moments, a young pulsar blasted jets of radio waves in Earth’s direction, seven times per second. Then, almost as quickly as they had appeared, jets from the dead, spinning star began fading. Puzzled, astronomers raced to study the object, termed J1906+0746, which is 25,000 light-years away in a globular cluster known as Terzan 5. Observations indicated that the incredibly dense, spinning star wasn’t alone: It was orbiting another dense, dead star, once every four hours. That stellar corpse’s gravity was so strong, though, that it had bent the fabric of space-time and was causing the pulsar to wobble in its orbit (or precess). For about a decade, that wobbling directed the pulsar’s beams toward to Earth. And then it wobbled away. Scientists at have estimated that the pulsar will again appear as a beacon in its Earth’s radio sky in 2170.
Did You Know? Long ago, a cascade of catastrophic collisions may have obliterated several planets in the inner solar system and left oddball Mercury as the only survivor. According to the new theory, there were once more planets inside Earth’s orbit than there are today. But as the solar system grew up and the planets shifted in their orbits, chaos descended upon these rocky worlds and hurled them into one another — a violent scenario that some scientists say could explain Mercury’s abnormally high density and strange, elliptical orbit. (For more, see “Mercury may be the sole survivor of planetary pileup,” by Lisa Grossman, New Scientist.)
Meeting Brief: When Supermassive Black Holes Collide
Packed with the mass of many billions of suns, supermassive black holes are like enormous cosmic drains that churn in the hearts of galaxies. Sometimes, these gargantuan drains collide. This is what scientists expect will happen in about 1 million years or so in a distant galaxy known as PG1302-102. There, scientists saw that the bright beacon of light shining from the galaxy’s center wasn’t shining ever so steadily. The team suspects those blips in the quasar’s light are the product of two supermassive black holes orbiting one another, less than a light-year apart. The eventual collision will likely release as much energy as 100 million supernovas and obliterate the galaxy – but it’s 3.7 billion light-years away, so not to worry.
Nearer to Earth, however, another pair of supermassive black holes appear to be on a collision course. Roughly 134 million light-years away, two merging galaxies, collectively called Arp 299, are slowly drifting toward a galactic smashup. But only one of the galaxies, as observed by NASA’s NuSTAR telescope, has an active supermassive black hole. The other cosmic drain appears to be snoozing.
Did You Know? ESA’s Planck satellite managed to indirectly detect what’s called the cosmic neutrino background – particle radiation imprinted on the universe two seconds after the Big Bang. The cosmic neutrino background is both older and colder than the better-known cosmic microwave background, which dates to roughly 400,000 years post-Big Bang. (For more information, here’s a technical talk from earlier this year.)
Meeting Brief: A Curious Exoplanetary System
Astronomers have spotted the first binary star system known to include both a Jupiter-type planet and a brown dwarf – a failed star that’s just a little bit too light to ignite. The two worlds orbit one of the sunlike stars in the binary known as HD 87646. One of the worlds, the planet with 12 Jupiter masses, orbits the star every 13.5 days. A year on the failed star, which has 55 Jupiter masses, takes 674 days. The strange configuration is 314 light-years away and appeared in data collected by the Sloan Digital Sky Survey’s MARVELS observation program. For six years, MARVELS has surveyed 60 stars at a time, looking for wobbles that betray the presence of planets. The “very packed environment” of HD 87646 challenges theories describing how planets form, says University of Florida astronomer Jian Ge.
Twenty years ago, the Hubble Space Telescope snapped one of its most iconic images ever. The three towering columns of gas bathed in the light of hot, young stars came to be called the Pillars of Creation — and they showed up on everything from t-shirts to coffee mugs to rugs. Now, to celebrate its 25th anniversary, Hubble has taken a new image of the well-known region in the Eagle Nebula, about 6,500 light-years away.
It’s even more glorious than the first.
Released today during the American Astronomical Society’s annual winter meeting, the new Hubble photo is sharper than the original (see full-size image here). It has a wider field of view, too, and reveals the tenuous base of the cold, gassy columns. Astronomers asked the telescope to shoot the same region in both visible and infrared light, which is relaying some interesting things about this place that’s come to be so familiar.
Infrared light can penetrate clouds of dust and gas that visible light cannot. So, when seen in the infrared, the pillars look like mere wisps set against a sea of countless stars. But inside those 5-light-year-tall towers are newborn stars. The uppermost tips of the pillars, the light blue parts that look as though they’re riding atop a bubbling cosmic eruption, are being pummeled by violent stellar winds. Perhaps as evidence of this stellar battering, a tuft of gas near the top of the tallest pillar is flying away.
And though these are known as the pillars of creation, astronomer Paul Scowen notes that they’re also regions of destruction. “I’m impressed by how transitory these structures are. They are actively being ablated away before our very eyes,” says Scowen, of Arizona State University, in a statement. He helped lead the original Hubble observations 20 years ago. “The ghostly bluish haze around the dense edges of the pillars is material getting heated up and evaporating away into space. We have caught these pillars at a very unique and short-lived moment in their evolution.”
Hovering on our cosmic doorstep is a weird little galaxy — something that looks way too young to live in our neighborhood. Just 39 million light-years away, dwarf galaxy DDO 68 appears primordial in composition and shape.
But is it?
The gossamer mass of stars and gas hasn’t yet coalesced into an identifiable structure, such as a spiral or an ellipse. And its elemental composition is simple, resembling that of the much younger universe. (As an aside, I would strongly recommend visiting the full-size Hubble Space Telescope image and swimming through that amazing sea of stars and background galaxies.)
Normally, such newborn galaxies aren’t found within a billion light-years from home. It takes a long time for light from primordial objects to travel across the universe and get to Earth; so, finding these small, faint time capsules is generally done by looking very, very far away. In other words, astronomers essentially peer back in time to when the universe was much younger. Through the lenses of our biggest eyes in the sky, we see these objects as they were billions of years ago (if all goes according to plan, the James Webb Space Telescope will soon be able to peer even farther back in time and detect even fainter, younger objects).
When we look closer to home, we tend to find galaxies that are older, larger, and more evolved. As these agglomerations of stars matured over the eons, they morphed from younger, simpler versions of themselves into the spectacularly complex structures we see today. They have distinct shapes, are populated by stars that are a mix of old and young, big and small, and have elemental compositions that are more complex.
That’s why finding this little guy was a surprise: It looks way too young for where it lives, kind of like a toddler moving in to a university dormitory and showing up for freshman chemistry lab.
But is DDO 68 as young as it looks? Astronomers aren’t sure. There are some enigmas swirling around in that hazy mass, including hints that some of those sparkling stars might be older than they’re letting on. Scientists are working on solving the mysteries that live in this strange little galaxy, and are attempting to determine its true age.
So is it a precocious youngster or a has-been masquerading as an ingenue?
Wrapped in dark matter, an object known as the Smith Cloud is hurtling toward the Milky Way at more than 150 miles per second. Now 8,000 light-years away, the gassy clump of hydrogen is expected to smash into the galaxy in about 30 million years.
But that won’t be the first time this blob of gas has met our galaxy: Scientists think it’s been here before, millions of years ago.
Normally, gas clouds don’t easily survive such encounters without being torn apart; to make it through, a cloud would need to be incredibly dense. Smith’s Cloud is not.
Astronomers initially proposed that the cloud’s strong magnetic field could shield it during its galactic passage. But new observations, made using the National Radio Astronomy Observatory’s Green Bank Telescope, offer another suggestion for how the Smith Cloud endures. Like a cosmic burrito, the cloud is wrapped in dark matter — the mysterious substance thought to comprise more than 80 percent of the matter in the universe. That dark shell protects the cloud from being shredded by the Milky Way (though it does appear to have a tail, like a comet, containing material that’s being sucked up by the galaxy).
Since interstellar clouds don’t usually come gift-wrapped, scientists now suspect Smith’s Cloud could be the gassy remains of a failed dwarf galaxy that never grew up and turned on its stars.
Every now and then, it’s good to take a moment and share a gorgeous space photo.
The glowing pink tuft in the center of this ESO image is the star-forming region Gum 15, located 3,000 light-years away in the constellation Vela. From afar, the colorful puff appears riven with dark voids that give it an almost organic appearance, like a chunk of tissue covered with dark blood vessels. (That dark fork is actually a thick patch of dust, though.)
Though beautiful, Gum 15 is a violent, blustery place, a stellar nursery shaped by wild young stars spewing radiation. Eventually, these young stars will age, explode and die. But before that, their energy and winds will continue to cleave the gentle clouds of their nursery and shave electrons from the surrounding hydrogen atoms. When those atoms recapture their lost electrons, they glow a characteristic red color – which is why Gum 15 shines as it does.
In the lower left is the star cluster NGC 2671, and in the lower right, you can see some of the tangled filaments of the Vela supernova remnant.
This concludes our gratuitous space photo presentation.
Finding stars is like finding cockroaches — where there’s one star, there are usually more.
Roughly half the stars in the Milky Way come in pairs, or binary systems, where two stars orbit one another in an endless cosmic dance (well, sometimes the dance ends in cataclysmic, fiery star death). Other stars live in clusters, like the one shown above in the Flame Nebula, 1,400 light-years away. These clusters are kind of like enormous family groups. Here, each stellar sister is born from the same clouds of collapsing gas and dust as her siblings.
Scientists used to think the oldest, first-born stars lived in the cluster’s center, where stellar ingredients are more dense and plentiful and it’s easier to make stars. But two new studies, posted to the arXiv [1,2], suggest this isn’t necessarily true. When astronomers studied sun-like stars in the Flame Nebula, and in another star cluster in the Orion Nebula, they found the oldest stars on the families’ fringes — in regions where it should take longer to light a star.
“Our findings are counterintuitive,” said Konstantin Getman of Penn State University, in a statement. “It means we need to think harder and come up with more ideas of how stars like our sun are formed.”
As with humans, determining stellar ages isn’t as simple as asking a star how old it is. Astronomers deduced stellar ages by measuring how bright a star is in X-rays and infrared light. Teams used NASA’s Chandra X-Ray Observatory to measure X-ray brightness, and then used that measurement to deduce a mass. Then, teams pointed several infrared telescopes at the same stars and took the second measurement. Comparing those brightness measurements with various stellar formation models yielded the stars’ ages.
In the Flame Nebula, the stars in the center were relative infants — just 200,000 years old. Their older sisters in the outskirts were already pushing 1.5 million years old. In the Orion Nebula, ages varied between 1.2 and 2 million years.
Astronomers aren’t yet sure how to explain their observations. One idea suggests that stars are born in the center and migrate outward, as though they’re growing up and leaving home. Another proposes that young stars are still being born in the cluster’s center, while star formation in the suburbs has ceased. And the third hypothesis suggests that young stars emerging from filaments of gas and dust fall inward, ending up in the middle.
Twenty-four years and two days ago, on a Tuesday morning, the space shuttle Discovery hitched a ride to low Earth orbit from Cape Canaveral, Florida. Aboard the shuttle? NASA’s newest eye in the sky, the Hubble Space Telescope, an instrument capable of peering deep into the cosmos and capturing the universe’s inhabitants in exquisite detail. It had taken decades of design and planning to get the telescope ready for work. The next day, on April 25, astronauts delivered the telescope to space.
Then, scientists eagerly waited for Hubble to start revealing cosmic secrets.
But a flaw in the telescope’s primary mirror meant the images weren’t sharp. Observing incredibly faint objects, such as very distant galaxies, wasn’t possible. It would be three years before the first of five servicing missions let astronauts correct the defect and upgrade Hubble’s vision to what it should have been.
Since then, though, the Hubble space telescope has continually delighted Earthlings with its breathtaking views of stars, galaxies, and our planetary neighbors. Its impact on science has been no less important. Among other discoveries, Hubble helped scientists determine that the universe is expanding at an accelerating rate. This discovery, which happened in the late 1990s, is something we still can’t fully explain.
Every day, tales of life and death in the universe are told through faraway supernovas, galactic collisions and clusters, and violent stellar nurseries. These stories are often accompanied by profoundly beautiful images. Some of these, like the million-second-long exposure that produced the Hubble Ultra-Deep Field, need to be viewed full-size for the appropriate amounts of cosmic oomph. Others, like the Pillars of Creation, have become extremely well-known — looking at these photos can be like seeing the smiling face of an old friend.
Here, in honor of Hubble’s 24th launchiversary, are 25 images that might be slightly less familiar…and I’ve added one to grow on, just for good measure.
As on Earth, young stars in space can be a handful. Blustery spasms produce violent stellar winds, tantrums that carve bubbles and cavities into surrounding dust and gas. Belches of intense stellar radiation dump energy into those clouds, exciting atoms and causing them to glow. In the photo above, just released by the European Southern Observatory, a hydrogen gas cloud blasted by these unruly young stars is glowing red.
Miranda looks like it’s been Frankensteined together. The small, lumpy moon orbits Uranus and has a surface covered by patches of intersecting ridges, weirdly bumpy terrain and pockmarked plains, and dark, irregular canyons. It’s kind of like a badly crafted moon-quilt, except there’s nothing warm and fuzzy about a barren chunk of icy rock with grooves that make the Grand Canyon look like a paper cut.
Earlier this week, I asked a bunch of scientists to share what they’ve been the most surprised by in the solar system. “The absolute weirdness of Miranda,” was one of the responses from planetary scientist Bill Bottke of the Southwest Research Institute. There are a number of bizarre satellites in the solar system, so Bottke pointing to Miranda meant it was worth a closer look.
Miranda was spotted in 1948 by Gerard Kuiper, but it wasn’t until Voyager 2 swung by the solar system’s most unfortunately named planet in 1986 that we got a good look at its little moon. Miranda is only 500 kilometers across, or about one-seventh the size of our moon.
Basically, Miranda appears as though it’s made out of pieces that don’t quite fit together properly, sort of like poor, lurchy Frankenstein. How the moon came to be like this is still a mystery. One theory suggests that in its first incarnation, Miranda was a less-grotesque, more-normal version of itself — until a giant impact or five came along and blew the moon apart. The pieces eventually reassembled, but not in a way that made much sense. Another hypothesis suggests that meteorite impacts locally melted the moon, and slush rising to the surface formed the giant, ridged patches scientists call “coronae.” Other theories have thrown in a little icy volcanism and internal heating caused by gravitational interactions with Uranus and its other moons. Or, Miranda could have begun to differentiate, with its internal layers separating into something like a core, mantle, and crust — but froze before it finished the job.
Peer closely at this photo and in the background, you’ll see galaxies the size of stars, and stars the size of galaxies [huge version here]. But in the foreground is the Monkey Head Nebula (NGC 2174), captured in the infrared by the Hubble space telescope. It’s a region of wispy, turbulent gas and dust clouds — chaos enveloping a twinkling stellar nursery. This beautiful patch of starry sky is in the constellation Orion, about 6,500 light-years away. The nebula gets its name from the shape it takes when viewed in wide-field. This image doesn’t really give you the full primate-in-the-sky experience, so I’ve used that as an excuse to paste in a set of photos below. Sit back and stare, click to enlarge.
When you watch the animation above, if you’re anything like me, two things will happen. First, you’ll start humming the Star Trek theme song (preferably not aloud), and second, you’ll be astonished by the enormity of this small slice of universe.
This recently released animation is a 3-D fly-through of what’s called the G15 field, mapped by the Galaxy and Mass Assembly survey project. Peering deep into the southern and equatorial skies, the project’s goal is to understand how galaxies are organized and how those shapes and structures evolve over cosmic timescales.
On large scales, galaxies tend to line up and form filaments. Those strands then twist themselves into an immense cosmic web. Between the strands are voids, or regions of mostly empty space. Or so we thought. Earlier this week, astronomers published a study describing a peculiar observation: Those voids have structures in them, too. They’re filled with delicate tendrils of galaxies (six, on average) that connect larger filaments to one another or to other voids. It’s the first time such small, stringy structures have been spotted, the team reported March 9 in the Monthly Notices of the Royal Astronomical Society.
Animation: Will Parr, Mark Swinbank and Peder Norberg/Vimeo. Constructed using data from GAMA and the Sloan Digital Sky Survey, the animation shows the real positions and images of the galaxies. Distances are to scale, but the galaxy images have been enlarged.