This Cassini photo shows two of Saturn's moons, Dione and Enceladus floating just beneath the ringplane. Smaller Enceladus is on the right, and measures 505 kilometers (314 miles across). Dione is further away at the top left, and measures 1,126 kilometers (700 miles across). This image was taken on October 15, 2005, when Cassini was 2.1 million kilometers (1.3 million miles) from Dione and 1.5 million kilometers (900,000 miles) from Enceladus.

On December 11, NASA's Opportunity rover will join its partner Spirit to celebrate a full Martian year on the Red Planet. Both rovers will now have experienced all of the Martian seasons, and now they're nearing the end of the Martian summer. Opportunity is currently exploring exposed bedrock along a route between Endurance and Victoria craters, and recently found rock that seems to be younger than what it discovered inside Endurance crater. These rocks seem to be petrified sand dunes, and show a longer term cycle of wetness and dryness in the region.

Get a flat while riding a bike and you fix it, though you may never see the tack on the road that caused the puncture. However on the failure of a space mission, the whole aerospace industry might be left scratching their heads as to what happened and why. David Harland and Ralph Lorenz in their book Space Systems Failures lay down the known space failures before the reader in great detail and full disclosure. There's the occasional rescue of launcher payloads that slightly lighten this otherwise negative subject, but from the number and variety of faults they leave no doubt that space ventures are more a gamble than a certainty.

Greetings, fellow SkyWatchers! The Moon is back and tonight it will dance with Venus. Selene and the bright planets will grace this week's night skies as our observing year rapidly draws to a close. There will be plenty of lunar features to study, as well as some very colorful stars. As luck would have it, we have not one - but two - meteor showers to watch as well! Let's head out to explore, because...
Here's what's up!

Scientists from NASA and the National Science Foundation have created a new way to view the Earth's atmosphere during space storms. These large-scale storms resemble weather cold fronts that result from plumes of electrified plasma that flash across the Earth's ionosphere. These plumes used to seem like random events, but scientists have gotten pretty good at predicting them now, using a fleet of spacecraft. For the first time, they can now directly connect plasma observed in the atmosphere with these plumes that can extend thousands of kilometres into space.

Rick Stankiewicz took this picture of a contrail shadow on the 17th, October 2005.

Do you have photos you'd like to share? Post them to the Universe Today astrophotography forum or email them to me directly, and I might feature one in Universe Today.

Gary Hatfield took this picture of Scutum Star Cloud from his place at Thaxton, VA.

Do you have photos you'd like to share? Post them to the Universe Today astrophotography forum or email them to me directly, and I might feature one in Universe Today.

The rise of complex life on Earth matches the appearance of oxygen in the atmosphere, and new evidence from University of Maryland scientists suggests that the increase was more gradual than previously believed. According to microbial evidence, oxygen first appeared in our atmosphere 2.4 billion years ago, and a second large increase started 1.3 billion years ago, and reached its current levels about 600 million years ago.

NASA's Chandra X-Ray Observatory has gathered 280 hours worth of data on the Perseus galaxy cluster to reveal massive amounts of turmoil in thousands of galaxies. Chandra discovered bright loops, ripples, and jet-like streaks. The supermassive black hole at the heart of galaxy NGC 1275 (Perseus A) is creating low pressure plumes of gas extending out for 300,000 light-years.

When galaxies collide, it's a messy affair. Gas, dust and stars are often spun out into space and can form into satellite dwarf galaxies that continue to orbit their parent galaxies. NASA's Spitzer Space Telescope has spotted a few dwarf galaxies in the process of formation around a recent merger in NGC 5291. Spitzer found that the dwarf galaxies are ablaze with star formation.

The Hubble Space Telescope took this amazing picture of the Crab Nebula supernova remnant. The star at the heart of the nebula exploded as a supernova nearly 1,000 years ago, and was recorded by Chinese astronomers as being bright enough to be visible during the day. This photograph was built up from 24 individual Wide Field and Planetary Camera 2 exposures taken over several years.

When ESA's Huygens probe touched down on the surface of Titan earlier this year, it hit hard, and then slumped sideways into the soft ground. After analyzing the landing in detail, ESA scientists have calculated that Huygens probably hit a surface similar to soft clay, lightly packed snow, or wet or dry sand. It penetrated about 10mm into the ground, and then settled slightly over time by a few millimetres, tilting the probe a few degrees. It's possible that Huygens landed on a Titan beach, shortly after the hydrocarbon ocean tide went out.

When ESA's Huygens probe passed through Titan's atmosphere on its way to a successful landing, it was buffeted by turbulence unexpected by scientists. Very little was known about Titan's atmosphere before Huygen's landing because the moon is shrouded by a thick hydrocarbon haze. Huygens found that the upper atmosphere was much thicker than expected, and broken up into several distinct layers. The probe also discovered possible evidence of lightning strikes around it.

ESA's Mars Express has confirmed findings by the NASA Mars Exploration Rovers that liquid water must have been present on the surface of Mars for long periods. Mars Express gathered evidence with its OMEGA instrument; a visible and infrared spectrometer, which discovered large quantities of hydrated minerals across the surface of the Red Planet. These minerals, such as phyllosilicates and hydrated sulphates are created by the chemical alteration of rocks by liquid water.

Now that its MARSIS radar instrument is working perfectly, ESA's Mars Express has turned up evidence of buried impact craters, layered deposits at the Martian north pole, and deep underground water-ice. One unusual discovery is a 250-km diameter (155-mile) circular structure buried under the ground; probably an impact crater which seems to be a rich source of water ice.

NASA researchers working with the Mars Exploration Rovers have released a new set of papers that describe conditions on Mars billions of years ago, when there were large areas of liquid water. Approximately 3.5 billion years ago, the terrain around Endurance Crater probably looked like the White Sands region of New Mexico: salt flats occasionally covered by water and surrounded by dunes.

Astronomers from Penn State University and the Harvard-Smithsonian Center for Astrophysics have found a miniature solar system in the making. A failed star with a hundredth the mass of our own Sun seems to have a planet forming disc of dust and gas surrounding it. With only 8 times the mass of Jupiter, this brown dwarf star is more like a large planet, and yet it's capable of forming a planetary system of its own.

Cassini has returned amazing photographs of ice volcanoes erupting from the surface of Saturn's moon Enceladus. On a previous pass of the moon, Cassini detected particles of water vapour stretching hundreds of kilometres above its surface, and this photograph shows the ice volcanoes in action. It's believed they're spewing out material that refreshes the ice in Saturn's E-ring.

Japan's asteroid explorer, Hayabusa, successfully touched down onto the surface of asteroid Itokawa Saturday for the second time in a week, and the Japanese Agency announced that it's clutching a sample of material. The spacecraft will now begin the long journey back to Earth, and it all goes well, its sample capsule should land in the Australian outback in June 2007. This will be the first time material from an asteroid will ever be sampled back here on the Earth.