A Sydney Aquarium diver uses a vacuum to clean the gravel in the Great Barrier Reef tank as a Ray Shark swims by September 26, 2006 in Sydney, Australia. The Aquarium is undergoing its annual spring clean to prepare for the school holidays using vacuums, along with sea creatures like Sea Cucumbers, Sea Urchins, Cleaner Wrasse Fish and Sea Stars to help complete the job. (Photo by Ian Waldie/Getty Images)

Shannon McGurgan (Bottom), Farhad Ahadi (Middle) and Malia Walsh (Top) perform the Circus Trick Tease on stage at a media call ahead of the inaugural Melbourne Circus Festival on September 23, 2011 in Melbourne, Australia. The National Institute of Circus Arts will showcase artists from around the world during the first ever circus festival in Melbourne from September 26 – October 2. (Photo by Hamish Blair/Getty Images)

Australian TV personality and singer, Dannii Minogue at the reveal of her wax figure to feature at Madam Tussauds Sydney on February 9, 2012 at the Sofitel, Melbourne, Australia. Madam Tussauds will officially open in Darling Harbour Sydney in May 2012. (Photo by Robert Cianflone/Getty Images)

Actor Rarmian Newton who plays the character Hiccup rides Toothless during a scene run through of the “How to Train Your Dragon Arena Spectacular” at Hisense Arena on March 7, 2012 in Melbourne, Australia. (Photo by Robert Cianflone/Getty Images)

Canadian escape artist Dean Gunnarson attempts to work his way out of a straight jacket while hanging from a crane by a rope which is on fire during a Royal Melbourne Show preview at the Melbourne Showgrounds on September 23, 2011 in Melbourne, Australia. The Royal Melbourne Show officially kicks off tomorrow, and continues until October 4. (Photo by Mark Dadswell/Getty Images)

The current world Champions in the Men's and Women's RS:X, Piotr Myszka of Poland and Blanca Manchon of Spain arrive at Bathers Beach carrying the ISAF World Championships Flag to be raised to officially open the 2011 ISAF Sailing World Championships on December 2, 2011 in Perth, Australia. (Photo by Mark Dadswell/Getty Images)

These spectacular images of the universe are the finalists in the 2016 CWAS “David Malin” awards. The annual competition, which celebrates the best astronomy images taken by Australian photographers, is part of AstroFest 2016. The winners will be announced on 16 July. An associated exhibition opens the following day at the CSIRO Parkes Observatory visitors centre, and a second exhibition will also travel to selected venues around Australia. Here: Mars and its Rival Antares and the Rho Ophiuchi cloud complex. (Photo by Phil Hart/CWAS/The Guardian)