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Think the photo’s impressive? Wait ’til you see the trailer for Hubble 3D, opening Friday in IMAX theaters.

The Arecibo Observatory under construction in 1961...

...and as it looks today. (NAIC / NSF)

William Gordon, the Cornell University engineer who dreamed up the world’s largest dish antenna, died this week at the age of 92. His recollections of the Arecibo Telescope’s early days were included in a story that ran in our October 1997 issue, not long after the observatory was upgraded with new telescope feeds:

When Bill Gordon first hiked into the mountain hollow in central Puerto Rico that today cradles the giant Arecibo Radio Telescope, it was nothing but tobacco fields and a small leaf-drying shed surrounded by tropical forest. It was 1958, and Gordon, then a professor of electrical engineering at Cornell University, had come up with a clever idea. His sponsor, the Pentagon’s Advanced Research Projects Agency (ARPA), wanted a radio antenna—a really big antenna—to study the thin upper atmosphere through which ballistic missiles would travel. But the 1,000-foot dish ARPA required would likely collapse under its own weight. Why not use the Earth itself for structural support, Gordon thought.

After searching through textbooks on karst topography—natural limestone depressions found throughout the world—and considering sites in Cuba (“Thank God we didn’t do that in 1958”) and elsewhere, Gordon and his colleagues settled on this particular bowl-shaped valley in Puerto Rico. Five years later, with funding from the Air Force, the Arecibo radio telescope opened for business.

Quick, what’s the most photogenic object in our solar system? Earth? Yeah, pretty. Saturn? Lovely rings. But for sheer drama and majesty, it’s hard to beat pictures of the sun taken from spacecraft like SOHO and STEREO.

Those satellites are about to be eclipsed (sorry) by the Solar Dynamics Observatory, which launched this morning from Cape Canaveral, Florida on an Atlas V rocket. The SDO will observe the local star across multiple wavelengths, at higher resolution and with a faster frame rate than any of its predecessors. In other words, we’re about to see the best high-definition movies ever made of the sun.

Oh, and there’s science, too.

At the recent American Astronomical Society meeting in Washington D.C., astronomers Peter Garnavich of the University of Notre Dame and Alex Filippenko of the University of California at Berkley described a whopping stellar explosion called Y-155. It started out as a Humpty Dumpty of a star, about 200 times the mass of the Sun. It became so hot at its core that it may have begun to produce matter/antimatter particle pairs, causing an instability that led to a runaway thermonuclear reaction and an explosion about ten times as bright as a Type Ia supernova, the next most powerful explosion known.

Stars more massive than eight of our suns typically end their lives in a supernova, like the one that created the Crab Nebula in 1054. Really big stars, however, between 150 and 300 solar masses, appear to advance to this next stage of antimatter-triggered destruction that scientists had theorized about for decades, and are now observing beginning with the best candidate, discovered in 2007. Luckily for us, Y-155 blew up halfway across the visible universe, about seven billion years ago.

The Crab Nebula supernova remnant. (Credit: NASA, ESA, J. Hester, A. Loll, ASU, Davide De Martin, Skyfactory)

In his 2008 book Death From the Skies, astronomer Phil Plait considered how big a stellar explosion would have to be, and how close, to end life on Earth. A Type Ia supernova would need to go off within about 25 light years of us, according to Plait, Filippenko, and Garnavich, to torch the ozone layer enough to disrupt the food chain. There are no stars this close to us on the verge of exploding. Plait offers an appendix of 24 stars within a thousand light years that will one day blow, but at that distance they won’t become much more than very bright. Eta Carinae, 7,500 light years away, will be a beauty, at a very safe distance, and apparently not big enough for an antimatter trigger. But if humans and books are still around then, we’ll be able to read the books at night by Eta Carinae’s light.

As for Y-155, it was more powerful than Eta Carinae would be, releasing at the peak of its explosion about 100 billion times the Sun’s energy output. “If Y-155 had exploded in the Milky Way, it would have knocked our socks off,” said Garnavich in his press release. What does that mean? He replied by email: “Whatever a Type Ia supernova could do, Y-155 could do it ten times better at the same distance.” Or, it could cause the same amount of destruction from three times farther out, as its energy falls off with the square-root of its distance. So if such a supernova occurred out to 75 light years, we’d be in serious trouble.

Fortunately, the chance of that happening these days is very low. Y-155 dates from an era when such huge stars are thought to have been more common due to the early Universe’s more pristine state—it had not yet been polluted by generations of supernovae, which create elements heavier than hydrogen and helium that appear to keep stars from getting so big.

Nice to be living in the modern era.

Long ago and far away. (Image: HUDF09 Team)

Sure it’s pretty, and sure it boggles the mind, but maybe the most astonishing thing about the Hubble Deep Field image is that some scientists were initially against it. To quote from an article in our August/September 1996 issue:

For Robert Williams, using the Hubble Space Telescope to peer deeply into the universe back to its horizon was a “no-brainer,” an experiment that somebody had to do sooner or later. Point the space telescope at an apparently empty patch of sky, take a long exposure, and see what turns up. When Williams first proposed the idea, though, not everyone was bowled over. “There were a lot of people who criticized it,” he says. “They thought it might not yield very many scientific returns, and that the time could be used better.”

As [then-] director of the Space Telescope Science Institute (STScI) in Baltimore, which administers the operation of the Hubble, Williams had the right to claim a small percentage of Hubble’s viewing time for his own projects. To be fair, though, he asked an outside panel to decide if his idea had merit. He never doubted the answer would be yes. “To me it was the compelling thing to do,” he says. His hunch proved well founded. The image that he generated last December [1995], known as the Hubble Deep Field, has revealed a timeline of ever fainter galaxies stretching back to the universe’s beginnings.

In fact, the HDF, as it’s known, is one of the most widely used images in modern astronomy, and has generated hundreds of follow-up studies. A successor, the Hubble Ultra-Deep Field, was taken in 2003-2004, and was the deepest (most sensitive) photo ever taken of the universe.

Until now. Hubble’s new Wide Field Camera 3, installed by shuttle astronauts last May, took this even deeper near-infrared photo during a four-day period in August, with a total exposure time of 48 hours. The faintest and reddest objects in the HUDF09 image are thought to be the oldest galaxies ever identified, dating from just 600 million to 900 million years after the Big Bang.

Read about the image and see a higher-resolution version here.