test 1 Astronomy - May 2018 USA | Page 33

Bombshell breakthroughs DISCOVERY OF URANUS. On March 13, 1781, William Herschel was searching for binary stars when he unintentionally discovered Uranus. He originally mistook the plan- et for a comet. NASA/JPL-CALTECH VOLCANOES ON IO. Engineer Linda Morabito inadvertently discovered Io’s volcano Pele in an optical navigation image taken by Voyager 1. Following Pele’s discovery, hundreds of smaller volcanoes were detected on Io over the years. NASA/JPL/UNIVERSITY OF ARIZONA X-RAYS AT THE CENTER OF THE MILKY WAY. While attempting to improve long-distance telephone calls, physicist Karl Jansky accidentally discovered that the center of the Milky Way is bursting with X-ray light (magenta). NASA/JPL-CALTECH problem is finding the things you don’t expect, which hide among the things you can recognize and the noise in the data.” Background and instrumental noise, as Penzias and Wilson know all too well, can be hard to quantify. As telescopes and instruments become increasingly complex, it becomes harder to under- stand the signatures they leave in the data. But being able to distinguish between noise and small, unexpected sig- nals is key in the search for the unknown. To tease out the unexpected discover- ies, Norris is helping develop a project known as the Widefield ouTlier Finder, or WTF. With the specific goal of aiding in unexpected discoveries, WTF will use complex algorithms and cloud computing to pull out unusual signals in the data and reduce the huge quantities of data to manageable amounts. Seek and you will find If you can’t find somewhere new to look, you can try looking harder than anyone else. This method paid off for astronomer Jocelyn Bell. While a graduate student at the University of Cambridge, Bell was charged with studying data from quasars — distant active galaxies — coming from a radio telescope. Amid all the signals, she noticed a source that varied too fast to be a quasar. She had discovered a new type of star: pulsars. This technique is the basis of surveys like the Large Synoptic Survey Telescope (LSST), which will survey the entire sky every few nights from its location in north-central Chile. “There are some quantifiable reasons why everyone believes LSST to be a major revolution for very rare objects and events,” says Željko Ivezić, project scien- tist of LSST and professor of astronomy at the University of Washington in Seattle. “The volume, the high dimen- sionality of measurements, and the mea- surement precision all bode well for unexpected discoveries and discoveries of rare objects and events.” Set to begin watching the night sky in 2021, LSST will provide continual sur- veillance of the heavens in an exhaustive manner. With a wide field of view the GAMMA-RAY BURSTS. In the 1960s, a U.S. spy satellite was searching for violations of the Nuclear Test Ban Treaty when it unexpectedly detected gamma rays coming from the sky instead of the ground. This was the first evidence for gamma-ray bursts, which are some of the most powerful explosions in the universe. ESO size of 40 Full Moons, LSST will take images at multiple wavelengths ranging from visible to near-infrared. Every clear night, it will log as much as 30 terabytes of data. Over its 10-year expected life- time, LSST plans on imaging each section of the sky a thousand times, creating more than 30 trillion observations of 40 billion celestial objects. This style of observation will naturally single out objects that change in bright- ness, such as pulsars, supernovae, and distant quasars, as well as moving objects, like asteroids and other small bodies in our solar system. The scientists hope it may also help identify new variable activ- ity in the night sky. Large-scale surveys have been carried out before, but never to the extent that LSST will go. Previously, the most exten- sive survey was the Sloan Digital Sky Survey (SDSS), which imaged only a quarter of the sky. LSST will use a tele- scope nearly three times larger, providing twice the resolution across a wider range of wavelengths of light, and it will view a greater portion of the cosmos. W W W.ASTR ONOMY.COM 33