M51 — The Whirlpool Galaxy © Martin Pugh
In a whirl. Pugh's grand prize-winning entry (which also won the "Deep Space" category) shows the Whirlpool galaxy's spiral arms in sharp detail; trails of light show a smaller, neighboring galaxy being slowly torn apart by the Whirlpool's gravitational pull.
Star Icefall © Masahiro Miyasaka
Ice cascade. The constellations of Orion, Taurus, and the Pleiades illuminate an ethereal icescape in Nagano, Japan (winner of the "Earth and Space" category).
Transit of Venus 2012 in Hydrogen-Alpha © Chris Warren
In passing. Venus passed between Earth and the sun on 6 June. The photographer captured the rare event—which won't happen again for 105 years—on a cloudy morning in Blackheath, London (winner of the "Our Solar System" category).
Pleiades Cluster © Jacob von Chorus
Sisterhood. The Pleiades, sometimes called the Seven Sisters, is a cluster of many young stars. The 15-year-old photographer captured this image after more than an hour of exposure (winner of the "Young Astronomy Photographer of the Year" category).
Simeis 147 Supernova Remnant © Rogelio Bernal Andreo (U.S.)
String theory. Remnants of a star that exploded roughly 40,000 years ago collide with gas and dust, forming the glowing "Spaghetti Nebula" (runner-up of the "Deep Space" category).
M51—also known as the Whirlpool galaxy—is a classic spiral galaxy that scientists have studied for centuries. But this mesmerizing new image of the galaxy has nabbed Australian photographer Martin Pugh the top prize in the fourth annual Astronomy Photographer of the Year awards, announced this week. The sharp detail of the spiral’s arms, defined by dark, dusty areas and bright, pink clouds of hydrogen, impressed the judges. "This is arguably one of the finest images of M51 ever taken by an amateur astronomer," said judge and astronomer Will Gater in a press release. Pugh’s photograph—which was chosen from more than 800 entries from around the world and earned him £1500—as well as those of the winners in categories such as "Young Astronomy Photographer of the Year," "Earth and Space," and "Our Solar System," are now on display at the Royal Observatory Greenwich  in the United Kingdom. Other standout entries include a photograph of the Pleiades cluster, taken by a 15-year-old astronomer, and an image of this year’s transit of Venus across the sun, which was taken on 6 June.