Scientists now believe that rogue waves - which can reach 30 metres (100 feet) high - are responsible for most of the large ship sinkings on the ocean. The ERS Earth observation satellites from the European Space Agency have spotted several of these elusive monsters, confirming their existence. A team of scientists studied a series of images of the Earth's oceans taken by the ERS satellites over a period of three weeks. In those images they found more than 10 giant waves taller than 25 metres. A new study will track the oceans for 2 years to get a better understanding of how they form, and if they can be predicted.

Cassini took this image of Saturn's moon Tethys on July 3, 2004 when the spacecraft was 1.7 million km (1 million miles) away. This heavily cratered moon is 1060 km (659 miles) across, and it's known to have a huge fracture that covers three-quarters of its circumference; although, this picture doesn't show it. Cassini is expected to make a close-up observation of Tethys in September 2005.

The theory that the expansion of our Universe is accelerating got another boost this week by a group of researchers from Princeton University. They used data in the Sloan Digital Sky Survey to measure the light from 3,000 quasars. They weren't looking at these quasars, though, but at diffuse hydrogen gas that sits in space partially obscuring the intervening space. The light from the quasars is changed depending on how much this gas that it has to go through. The astronomers were able to get a sense of how this gas clumped together over time, and their results exactly match the inflationary model of the Universe.

As part of their efforts to return the space shuttle fleet back to operation, NASA engineers tested out a complete Space Shuttle Main Engine on Monday. The test ran for 520 seconds, which is how long the shuttle takes to get into orbit, and it looks like there were no problems. The engine will next be shipped out to the Kennedy Space Center for installation into the space shuttle Discovery. If the Return to Flight tasks go well, the next flight, STS-114, could launch as early as March 2005 to return to the International Space Station.

NASA's Cassini spacecraft took this image of Rhea, Saturn's second largest moon on June 2, 2004, when it was 990,000 km (615,000 miles) away. Rhea is 1528 km (950 miles) across, ancient, and cratered. More than 20 years ago, Voyager discovered that one of its hemispheres has bright, wispy streaks that might be deposits of water ice. Cassini is expected to fly only 500 km (311 miles) away from Rhea on November 26, 2005, so we've got a bit of a wait before getting the extreme close-up view.

NASA's Spitzer Space Telescope has uncovered a group of ancient galaxies that had eluded astronomers using other telescopes. The primordial galaxies were originally discovered using the UK's SCUBA instrument on the James Clerk Maxwell Telescope in Hawaii, but the instrument wasn't fine enough to determine which were galaxies in the background, and which were actually groups of galaxies, or objects in the foreground. Spitzer resolved the issue in only 10 minutes, giving the SCUBA team a new method of confirming their findings.

NASA has shortened its list of potential missions for its New Frontiers program down to two spacecraft. The first is called "Moonrise", and would send two identical landers to the Moon's south pole - which is believed to have water ice mixed in with the lunar soil - to return 2 kg (5 lbs) of material back to Earth. The second is called "Juno", and would send a spacecraft into a polar orbit around Jupiter to study the giant planet in great detail. Both missions will receive $1.2 million in funding to perform 7-month feasibility studies to see if they can launch by June 2010 at a cost of less than $700 million.

Astronomers have detected a small bright spot on a familiar neutron star, Geminga, located 500 light-years away. The hot spot was discovered using the XMM-Newton x-ray observatory, and it's the size of a football field. Geminga itself is only 20 km (12.4 miles) across, and spins 4 times a second, but it's got 1.5 times the mass of our own Sun. The hot spot is created because material ejected from the rapidly spinning object is being recaptured by its gravity, and then funneled by its magnetic field to strike a specific point, heating it up millions of degrees.

After several days of delays, NASA's Aura Earth observation satellite launched on Thursday atop a Boeing Delta II rocket. The liftoff was from Vandenberg Air Force Base at 1002 UTC (6:02 am EDT), and the spacecraft separated 64 minutes later. Once its science mission begins in the next few months, Aura will sample the Earth's atmosphere to help scientists answer several questions: is the ozone layer recovering? what processes affect air quality? and how is the Earth's climate changing?

Engineers with NASA have decided to get Spirit to drive up the Columbia Hills backwards because of an ongoing problem with one of its wheels. The problem cropped up a few months ago, when one of its front wheels started getting extra resistance; they've tried heating it, and giving it rest, but nothing's worked. Spirit is now keeping the wheel locked, and then driving backwards, dragging it along like an anchor. This has saved power, but slowed down its speed a bit. Spirit will still use the wheel when it's trying to cross difficult terrain.

Why does Iapetus have a dark side and bright side? That's a mystery scientists hope that the Cassini spacecraft will be able to solve as it spends the next few years orbiting the Saturnian system. The unusual light/dark nature of the moon was first revealed when the Voyager spacecraft swept past the moon more than 20 years ago. One theory is that the moon was coated by some other foreign material, but only on one side. Another idea is that it's being resurfaced from material inside the moon. This image was taken when Cassini was 3 million kilometres (1.8 million miles) away.

The world's largest commercial communications satellite, Telstar's Anik F2, was launched atop an Ariane 5G rocket today. The rocket lifted off from the European Spaceport in Kourou at 0044 UTC (8:44 pm EDT July 17), and carried the 5,950 kg (13,118 lb) satellite into a geostationary transfer orbit. Once it reaches its final orbit at 111.1 degrees West, the Anik F2 will provide data and broadcast services to all of North America.

It appears that Jupiter and Saturn formed in completely different ways, according to a new computer simulation sponsored by the Los Alamos National Laboratory. If the simulation is correct, heavy elements ended up concentrated at Saturn's heavy core, while they're spread pretty evenly around in Jupiter. This would indicate that a different process built up the two planets. The team ended up running 50,000 different scenarios based on every possible variation permitted by known astrophysics.

The European Space Agency is considering an ambitious new mission that will attempt to move an asteroid. Named Don Quijote, the mission would include two spacecraft: Sancho and Hidalgo, and launch as early as 2010-2015. The Sancho portion would rendezvous with an asteroid, study in in great detail for seven months, and then watch as Hidalgo smashes into it at tremendous speed. The impact would slightly shift the orbit of the asteroid, and give scientists an understanding of how much force would be required to move future space rocks. Five other missions were considered, including three observation, and two rendezvous missions.

Scientists from Columbia University and Rensselaer Polytechnic Institute have created a detailed map of Lake Vostok, which is buried 3,700 to 4,300 metres beneath the surface of Antarctic ice. They found that the lake is actually broken into two different regions; water probably doesn't flow between them. That means that scientists could find two completely different ecosystems, which have separately evolved to live in this hostile environment. By drilling down and sampling the water of Lake Vostok, scientists will learn important lessons about how to go about determining if there's life on Europa - one of Jupiter's moons which seems to have liquid oceans encased in ice.

Although Cassini has arrived at Saturn, NASA is still releasing photos it took of the Ringed Planet before it arrived. Here's a picture taken on May 22 when the spacecraft was 22 million km (13.7 million miles) away from Saturn. It was taken using a special filter which is sensitive to the emissions and absorption of methane gas, giving scientists a great view of the planet's cloud structures.

When astronomers first realized that the stars in the sky were like our Sun, only more distant, they wondered if those stars had planets too. And if they have planets, is there life? Intelligent life? There's an answer - yes or no - but we don't know it yet. NASA and the European Space Agency are working on a series of space and ground-based observatories that may help get an answer soon. In just a decade, you could gaze into the night sky, locate a star, and know that there's life there. Life could be everywhere.