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What’s cool about the universe is that if you stare at nothing long enough, you’ll see something big. That’s what scientists have done with the Hubble Space Telescope a few times, creating the enchanting Hubble Deep Field images with swarms of galaxies that have opened our eyes to the immensity of the cosmos.

But sometimes the universe comes to you, as it did last April 23 when a gamma ray burst now named GRB 090423 was detected by NASA’s orbiting Swift satellite. Gamma ray bursts are the most violent explosions known, and occur when a star perhaps 20 times the size of our sun exhausts its fuel. Its core collapses under the force of the star’s gravity and becomes a black hole while outer layers fly off. Then matter falling into that hole produces a powerful jet of gamma rays that flare outward in opposite directions. If one of those jets is pointed at us, it is so energetic that (we now know) we can detect it from a distance of 13.1 billion light years, which is how far away this burst originated. That’s more than 95 percent of the distance across the known universe, and 190 million light years farther away than the previous record holder.

Artist's concept of the evolution of a star into a gamma ray burst. Credit: Nicolle Rager Fuller/NSF

Astronomers estimate the explosion occurred 630 million years after the Big Bang, when the first stars were forming. Astronomers also think the first stars formed no earlier than 150 million years after the Big Bang. So GRB 090423 would have been only a few hundred million years old when it blew. That sounds like a big number until you compare it to the age of stable stars such as our sun that burn for 10 billion years before they swell into a red giant, then smolder into a white dwarf for another five billion or more.

Here’s a good video on the Nature web site that explains it.

Just when you thought Saturn’s ring situation couldn’t get any cooler than the recent equinox photos by Cassini, make way for the mega-ring. Astronomers Anne Verbiscer, Michael Skrutskie, and Douglas Hamilton just announced that they’ve discovered a fantastically huge ring around Saturn. Their tool was the Spitzer Space Telescope, which orbits the sun in an Earth-trailing orbit about 66 million miles away from us.

For years astronomers have wondered why Iapetus, one of Saturn’s many moons, appears encrusted on one side with material dark as asphalt, while the rest of the moon is quite bright. Turns out it may be getting a steady pie-in-the-face from another Saturnian moon, Phoebe, associated with the debris in the ring.

Phoebe’s a bit of a rogue, a very dark moon that orbits way out from Saturn—about eight million miles—and in the opposite direction of most of the planet’s other moons. By using Spitzer’s super-cold instruments that can detect infrared radiation from objects, or in this case fields of debris, that are a couple hundred degrees below zero F, Verbiscer and her colleagues found that Phoebe was orbiting within an enormous ring of fine particles no one had ever detected. Some of the ring’s debris probably falls onto Iapetus, which orbits just inside it, and may account for the moon’s yin-yang look. For a high-resolution version of the image below, click here.

Saturn's new mega-ring, and the moons that led astronomers to it. Credit: NASA/JPL-Caltech.

The matter in the mega-ring is tiny—most objects are specs of dust about ten microns across. They’re also diffuse, with a distribution of only about 30 grains per cubic mile. If you ended up in the ring, you wouldn’t even know it. “Cassini flew right through it on its way to Saturn,” says Verbiscer of the spacecraft’s arrival in the summer of 2004. “The ring is so big, the spacecraft had to keep flying another two weeks inside the ring before it even got to orbital insertion.”

Infrared view of Saturn's big ring, viewed edge-on, and a diagram of the relative size of Saturn compared to ring thickness. Credit: NASA/JPL-Caltech/A.Verbiscer (Univ. of Virginia); Saturn photo by Hubble Space Telescope

Since then, Cassini’s orbits have kept it well inside the ring, which is about 300 Saturns in diameter, and about 20 Saturns thick. Really, more like a doughnut than the planet’s standard rings. Like Phoebe’s orbital plane, the big ring is inclined 27 degrees to the planet’s other rings.

Will Verbiscer soon point Spitzer’s chilly sensors at Jupiter next, in search of a Jovian mega-ring? She chuckles. “It’s a logical next step, isn’t it?” But, she adds, “No formal plans at this point.”

Hubble, re-released. What's next, Knighthood?

We sure do love our celebrities, don’t we? And I don’t mean whatsisname, who won on American Idol last night. I’m talking about the newly upgraded Hubble Space Telescope, whose astronaut repairmen received a call from President Obama yesterday, and will deliver live testimony from space at a Congressional hearing today. An appearance on Leno is a shoo-in.

What other science instrument has Hubble’s star power? Maybe the Spirit and Opportunity Mars rovers, but that’s about it. And mostly, it’s deserved. Hubble is the sharpest, most sensitive eye on the sky we have. But it’s not the only one, nor the best we’ll ever build. And therein lies a point.

Six years ago, the astronomy community faced a decision—keep Hubble going, or abandon it, move on, and use the money to build newer, better space telescopes. Hubble won out, but the choice wasn’t easy, and it had a downside. Due partly to the added cost of more upgrades (and mostly to other NASA budget pressures), there hasn’t been money for other astronomy projects, like building telescopes to hunt for Earthlike planets or study dark matter.

Hubble is fabulously expensive—its total cost to design, build, launch, and operate is estimated at upwards of $9 billion in today’s dollars. And that doesn’t count the five shuttle missions to repair and upgrade it at regular intervals. This most recent repair job alone cost nearly $1 billion.

Is Hubble worth it? Depends on how you measure it. One analysis of citations in scientific papers (a common measure of “productivity”) found that Hubble observations accounted for 19 percent of the citations in astronomy papers published in 2001, the largest number for any optical-wavelength observatory. But the number of citations per paper was only average compared to other optical observatories like Keck.

This is hair-splitting, sure, and not meant to sound ungrateful for the skillful repair job by the STS-125 astronauts. Hubble is an awesome, historic instrument. But should we become so celebrity-struck that we only pay attention to the star performers? Bureaucratically, it’s always easier to feed a few big projects than a lot of little ones, however deserving. And that’s a habit we may someday have to break.

Cast a cold eye: Spitzer's view of the Helix nebula

It’s a big week for space telescopes. Hubble’s getting an upgrade, Europe’s Herschel (the largest mirror ever sent into space) and Planck observatories are on the pad awaiting a Thursday launch, and the six-year-old Spitzer space telescope is about to start its second life. Any day now (May 12 was the estimated date, but it could happen as late as June), Spitzer will run out of the liquid helium coolant that gives its infrared detectors their fantastic sensitivity. For some infrared telescopes, that spells the end. For Spitzer, it’s just another phase.

Project scientists have long planned for what they call the “warm Spitzer” mission (man, there’s a project crying out for a naming contest), in which those onboard instruments that still work at higher temperatures—a relative term, since we’re talking about minus 404 degrees Fahrenheit—will be used mostly for long-term surveys.

One of the most intriguing of these will be a survey of at least 750 near-Earth objects, a significant sample of the 6100-plus NEOs discovered to date. Most are known only as moving dots of light against the stellar background. Spitzer will fill out the profile with data on each object’s temperature, chemistry, mineral content, and reflectivity. We won’t get pictures, but astronomers can deduce an asteroid’s size and density from its temperature and brightness. And that will give us, for the first time, a distribution showing the relative abundance of large and small asteroids in Earth’s neighborhood. It should also help scientists tell the dead comets from the ordinary asteroids.

Not bad for a telescope whose main mission has ended.

Two of the Amherst monoliths.

Judith Young wore a light, sheer robe, almost a wrap, that reached to within inches of the floor, over silky, swishy pajama-looking clothes. Very comfortable looking, the kind of new age-y clothes an academic wears so she can devote all her energy to thinking. Her long gray hair reached down her back to her waist. And she stayed in motion, from the podium to the screen and back again. She had a room full of eyes and ears riveted on her in the briefing room at the Smithsonian National Air and Space Museum on Tuesday, where she spoke about teaching astronomy outdoors with a time-tested circle of stones, or sunwheel.

While the most famous example of a sunwheel is England’s Stonehenge, Young got her inspiration one summer on a visit to a ranch in Montana. There, a smaller, eroded sunwheel on former Blackfoot Indian territory lay near a cave. While no one’s dated that sunwheel, artifacts found in the cave indicate human settlement in the area predating Stonehenge. Looks like Native Americans were in on the sunwheel act before the Europeans, she suggests.

“I don’t think that the first solar calendars were kept for very complicated reasons,” said Young. “Life was pretty hard thousands of years ago. It was worth noting that you had lived through a winter. Once they realized that there was a cycle, they may have started keeping track of how many winters they had survived.”

Young returned to the University of Massachusetts at Amherst, where she teaches astronomy, and set about building her own sunwheel. After several false starts on a remote, undeveloped part of campus—the university wanted to know when the first human sacrifice would happen—Young got a National Science Foundation grant. This translated to serious granite monoliths, some weighing up to four and a half tons, delivered by a local quarry. Fifty-one tons of gravel later, each of the 16 new stones had its own base and a thick, flat foundation stone. Each monolith is secured with a long stainless steel spike anchor and is glued down for good measure, to keep the curious football players from trying to topple one post frat-party.

Since completing the project in the fall of 2000, Young has entertained school groups from second graders to grad students at the site, where they watch the sun rise and set over specific monoliths on the summer and winter solstices, and the autumnal and vernal equinoxes. She speaks of how the sunwheel, “the first unique stone circle calendar in the world on a university campus, enhances a sense of connection to the universe. It connects Earth and sky, sun and stone, matter and energy, science and art, past and present, and the observer and the horizon.” Already, she says, it has inspired other wheels in eastern Massachusetts, California, and Colorado, Japan, Germany, The Netherlands, and Australia. Young has a log at the site for visitors to sign. Her website goes into detail on the history of sunwheels and how to use them.

“With 30,000 signatures,” says Young, “it’s now the second biggest tourist attraction in the region after the Emily Dickinson House.”