The European Southern Observatory — a bottomless reservoir of mind-blowing space photos — issued a challenge last October to amateur astronomers everywhere: Find the best photos that ESO's professional image processors overlooked. The results are in. The ESO announced the best astrophotos dug from its archives in the "Hidden Treasures" competition. Contestants had to start with raw, grayscale data taken with one of the observatory's constellation of telescopes, which includes the Very Large Telescope (actually four separate telescopes working together), VISTA, APEX, the La Silla Paranal Observatory and ALMA. After correcting the image for distortions and unwanted signatures of the telescope, contestants could process or enhance the raw data however they wanted, short of painting directly on the image. ESO got about 80 submissions, and selected 10 winners based on the "quality of the data processing, the originality of the image and the overall aesthetic feel." The grand prize winner, Russian astrophotographer Igor Chekalin, will get a free trip to the Paranal Observatory in Chile and a chance to participate in an observing run. You can sift through the whole set of photos on flickr. Here are some of our favorites. This page: Orion Nebula The watercolor-like portrait (above) of the Orion Nebula was processed by Russian astrophotographer Igor Chekalin. The image was captured in early January 2005 with the Wide Field Imager camera on the 2.2-meter telescope at the La Silla Observatory in Chile. The nebula gives astronomers a close-up view of a stellar nursery, where stars are born from condensing clouds of dust and gas. ESO has also released its own reprocessed version of the same data (below). Images: ESO/Igor Chekalin.

Messier 78 Chekalin won the trip to Chile for this image of M78, another center of star formation in the Orion constellation. This image was also taken with the Wide Field Imager on the 2.2-meter telescope at the La Silla Observatory in Chile. M78 is a reflection nebula, a cloud of interstellar dust that shines with light reflected from young, bright blue stars. These young stars eject jets of matter, forming the dramatic sculpted outflows in the image. "It was great experience, not only winning, but working with perfect raw data from a large professional instrument with a modern high-resolution camera," Chekalin wrote to Wired.com in an e-mail. "Processing for such data is quite different from the usual amateur astrophotographer job. I've learned very much." Image: ESO/Igor Chekalin.

Antennae Galaxies This shot of the Antennae Galaxies (NGC 4038 and NGC 4039) was processed by Italian astrophotographer Alberto Milani. The two galaxies in this image are in the middle of a head-on collision, violently ripping each other apart and tossing long tails of stars, dust and gas away from the galaxies' centers. In about 400 million years, the pair will fully combine to form a single, larger galaxy. Astronomers think every large galaxy goes through a similar merger at least once. Our own Milky Way is headed for a collision with the nearby Andromeda Galaxy in about 4.5 billion years. Image: ESO/Alberto Milani

Messier 74 The great spiral galaxy M74 dominates this image from Manuel Mejias of Argentina. M74 (also known as NGC 628) is one of the best examples of so-called "grand design" spiral galaxies, with well-defined arms. Like the Antennae Galaxies, M74 has been shaped by interacting with its galactic neighbors. But instead of destroying the spiral, these interactions actually enhanced M74's remarkable symmetry. Gravitational nudges from nearby galaxies triggered density waves that sweep around the galaxy's gaseous disk, piling material into the spiral arms. This image was taken using the FORS1 instrument on the VLT. Image: ESO/Manuel (Manu) Mejias

NGC 3169 and NGC3166 Russian astrophotographer Igor Chekalin also submitted this shot of galaxies NGC3169 (left) and NGC3166 (right). The two galaxies lie just 50,000 light-years apart, half the diameter of the Milky Way. They gravitationally distort each other's spiral structure. The image also captures the supernova SN 2003cg, which was discovered in May 2003. This image was taken with the Wide Field Imager on the 2.2-meter telescope at the La Silla Observatory in Chile. Image: ESO/Igor Chekalin

Moon This haunting shot of the crescent moon, the only photo of a planet or satellite in the contest, was created by Andy Strappazzon of Belgium. He took third prize. The raw data came from the Wide Field Imager on the 2.2-meter telescope at the La Silla Observatory in Chile. The image was taken June 14, 2002. Image: ESO/Andy Strappazzon

NGC 3582 This fiery photo of the star-forming nebula NGC 3582 was processed by American astrophotographer Joe DePasquale. "The massive loops of ionized gas expelled by dying stars remind me of solar prominences," the bright loops of charged plasma that sometimes erupt on the sun, DePasquale said. The data for the image was taken with the Wide Field Imager on the 2.2-meter telescope at the La Silla Observatory on June 16, 2002. Image: ESO/Joe DePasquale

NGC 3621 Joe DePasquale also processed this shot of the spiral galaxy NGC 3621, located 22 million light-years away in the constellation Hydra. Some of the galaxy's brighter stars have been used as "standard candles" to establish estimates of distances between galaxies and the scale of the universe. This image was taken with the Wide Field Imager on the 2.2-meter telescope at the La Silla Observatory in Chile. Image: ESO/Joe DePasquale

NGC 1073 This shot of the barred spiral galaxy NGC 1073 was processed by Ukrainian astrophotographer Oleg Maliy. "I'm a newbie in the astrophotography-imaging process," Maliy wrote on his flickr page. "This is the first work in my life." Image: ESO/Oleg Maliy