Imagine a solar powered sail that could propel a space craft through the vacuum of space like a wind that drives a sail here on Earth. The energy of photons steaming from the Sun alone would provide the thrust. NASA and other space agencies are taking the idea seriously and are working on various prototype technologies. Edward Montgomory is the Technology Area Manager of Solar Sail Propulsion at NASA. They just tested a 20-meter (66 foot) sail at the Glenn research center's Plum Brook facility in Sandusky, Ohio.

Take a good look at Saturn's moon Iapetus and it has a few striking features that set it apart from every other object in the solar system. For one thing, it seems to have two faces: one white, like freshly fallen snow, and the other dark like volcanic rock. But even stranger, Iapetus has a seam. Right at the equator, and going halfway around the planet, it's probably 20 km (12 miles) high - as if the moon was cut in half and then smashed back together. Planetary geologists have assumed this seam is volcanic in origin, but Paulo C.C. Freire of the Arecibo Observatory has another suggestion. In the distant past, Iapetus gobbled up one of Saturn's rings.

Cassini took this image of two of Saturn's moons, Dione and Tethys, perched together near the planet's rings. Dione is the upper moon in the picture, and occults part of Saturn's rings. This image shows the contrast between the moons: Dione looks much smoother than Tethys' crater battered surface. The photo was taken on March 19, 2005, when Cassini was approximately 2.7 million km (1.7 million miles) from Saturn.

After a brief glitch last week, the European Space Agency's Mars Express spacecraft has successfully deployed the first of its MARSIS booms to its full length. The 20 metre (66 foot) boom is composed of 13 segments, but one joint didn't fully lock into place. Controllers turned the cold side of the boom into the Sun, which heated it up, and forced it into place. With the first boom complete, controllers will extend its two additional booms within a few weeks, so Mars Express can begin searching for underground sources of water.

I heard on the radio today someone bemoaning the fact that, after 18 years, they will no longer have new Star Trek episodes to watch. The current and apparently final rendition is Star Trek Enterprise that, as a prequel, fills in the Star Trek time line between the discovery of the warp drive engine and the original series with Kirk, Spock, McCoy and company. Though there won't be new episodes, lots of fun can still be had from (re) watching the old Star Trek episodes, including those in the new collection Star Trek Enterprise - Season 1.

Usually it's the biggest things that get the news, but an international team of researchers have demonstrated that the tiny might be just as important. They spotted the smallest coronal mass ejection (CME) ever seen on the surface of the Sun, produced from a region not much bigger than the Earth. This sounds big, but it's a fraction of the size of those huge CMEs we normally see in pictures of the Sun. Amazingly, the magnetic field lines in this pint-sized CME were 10x more twisted than their larger cousins.

Monday's gamma ray burst might have been just what astronomers have been hoping to see for decades - the birth of a new black hole. GRB 050509B was a short gamma ray burst, lasting only 50 milliseconds, which means it could be the result of a collision between two neutron stars, or even two black holes. NASA's Swift observatory detected the explosion, tracked its location, and focused its large telescope within a minute of its occurrence.

A researcher from Washington University in St. Louis is developing techniques that will help understand how early life developed and diverged here on Earth, to help predict where and what form it might take on Mars. Carrine Blank has traced the genetic relationships between different classes of bacteria, and determined when they broke away from each other to evolve into distinct organisms. These patterns of divergence have happened in several places on Earth, so it's possible they happened on Mars too.

Think astronomy is a boring task of poring over data or staring at star chart after start chart? Sometimes, it can get downright exciting, like when a worldwide alert goes off signifying a new gamma ray burst in the sky. Monday, May 9, 2005 saw not one, but two, gamma ray bursts as NASA's HETE-2 and SWIFT x-ray satellites each managed to sound the alarm from low-earth orbit. One of these events may prove to be just the breakthrough needed to help astrophysicists better understand just how such highly explosive events actually come about. But they've really got to hustle to get the objects imaged before they fade away, and take all their secrets with them.

Cassini has confirmed the discovery of a previously unseen moon tucked in a gap in Saturn's A ring. The moon, provisionally called S/2005 S1 for now, is only 7 km (4 miles) across, and orbits within the Keeler gap. Even though it's so small, you can clearly see the effect of its gravity on the nearby ring edge, which has distinctive waves along its edge. The is the second moon ever discovered within Saturn's rings. The first, Pan, is 25 km (16 miles) across and orbits within the Encke gap. All the other moons are outside the ring system.

With the launch of NASA's Swift spacecraft, Gamma Ray Bursts - those "most powerful explosions in the Universe" - have been in the news on a regular basis. When a GRB is detected, a worldwide network of instruments tune in and image the afterglow in every possible wavelength, from radio to visible to gamma ray. But some bursts are "dark", causing a brilliant flash in gamma rays, but absolutely nothing in the visible spectrum. The "dark gamma ray bursters" are a mystery to astronomers, but a team of international astronomers think they have a way to narrow down the search for an explanation.

Our Sun can flare up from time to time, but probably nothing like the superflares it created in its early days. According to new observations by the Chandra X-Ray Observatory of a nursery of young stars in the Orion Nebula, young stars can produce flares on an incredible scale - many times greater than anything we'd see on the Sun today. Surprisingly, these flares might force rocky planets to keep their distance from their parent star, preventing them from spiraling in to their destruction.

NASA's Cassini spacecraft took this photograph of Saturn's chaotic, tumbling moon Hyperion. Only 266 km (165 miles) across, Hyperion one very large crater which scientists are trying to use to pin down just how quickly the moon is spinning. This image was taken by Cassini on March 19, 2005 when the spacecraft was just 1.3 million km (824,000 miles) away - its second best view of the moon so far.

Greetings, fellow SkyWatchers! We'll begin the week with a challenging unaided eye observation and head out to deep space as we venture toward NGC 2903 and the "Sunflower" Galaxy. The Moon will soon join the scene and we'll explore some of its nightly features, but not before we've had a chance to catch two comets! There will be occultations, jovian activity and a new double star to delight the eye, so head out under dark skies because...

Here's what's up!

The European Space Agency's Mars Express took this image of 140-km (87 mile) Crater Holden on the surface of Mars. This crater is very old, with numerous smaller impact craters inside it, which formed later. It's also heavily eroded, with the characteristic central mount nearly completely covered by sediments. The rim of the crater has been cut in several places by gullies, which seem to form small valley networks.

Controllers with the European Space Agency have deployed the first of Mars Express' MARSIS radar booms. During the operation, however, they detected an anomaly with one of the 13 segments that make up the telescoping boom - segment 10 hasn't fully locked into place. Controllers are going to hold off extending the second boom until they can figure out what's happening with the first. Once fully deployed, the MARSIS radar will allow Mars Express to map the subsurface of the Red Planet, searching for underground reservoirs of water.

Saturn's moon Phoebe might have arrived at the planet after a long journey from the outer Solar System, according to new research from NASA. When Cassini analyzed the heavily cratered moon in June 2004, it found that it was ice rich, but covered with a thin layer of darker material. This is a similar composition to Pluto and the Kuiper Belt Objects. Phoebe likely started further out, but then was redirected towards the inner solar system through interactions with other objects. Finally, it was captured by Saturn into a stable orbit.

Scientists analyzing images taken by the Mars Global Surveyor think they might have located the Mars Polar Lander spacecraft, which crashed onto Mars in December 1999. The team developed techniques for spotting spacecraft by analyzing the landing sites of the Mars Exploration Rovers, Spirit and Opportunity. They think they've found MPL's parachute, exhaust blast, and the actual spacecraft. Additional, higher resolution images will be taken by MGS later this year to confirm the discovery.

The European Space Agency's Envisat satellite snapped this picture of a marine phytoplankton bloom forming off the coast of Spain, in the Bay of Biscay. Blooms like this occur frequently in the bay this time of year, since the water is cold, but very nutrient rich. As the water warms to a certain level, the plankton's growth explodes. It's important to monitor these blooms, as phytoplankton forms the base of the marine food chain.