Researchers are finding that the mysterious dark energy found to be accelerating the expansion of the Universe is remarkably well predicted by Einstein's cosmological constant. Einstein originally added this constant to balance out the gravitation of the Universe, but threw it out after seeing evidence of the Big Bang. An international team of researchers has performed the Supernova Legacy Survey, and found that it calculates dark energy to be within 10% of Einstein's prediction.

If you're going to be traveling by airplane, take a look out the window; you might be amazed. On the side opposite to the Sun, you could see the shadow of the airplane in the clouds, and shimmering rings of colour surrounding it. Look out the sunward side, and you might see ice halos - arcs of light caused by ice crystals in the high clouds. And don't forget to look up. You're above much of the Earth's atmosphere, and should be able to see a clearer view of the night sky than from the ground.

In this Cassini image of Saturn's moon Dione, you can see the wispy features that run across its surface. It's also possible to see the craters Dido and Antenor near the moon's terminator at lower left. Cassini took this image on October 9, 2005 from a distance of 1.8 million kilometers (1.1 million miles).

NASA's Mars Reconnaissance Orbiter fired its main engine for 20 seconds on Friday, fine-tuning its course towards the Red Planet. The spacecraft is schedule to reach Mars on March 10, 2006. Since its August 12 launch, the spacecraft has traveled about 60% of the distance between Earth and Mars, and it will make 4 more adjustments before arriving at Mars. Once it does arrive, MRO will spend about half a year adjusting its orbit before beginning its science phase.

The branch of science called physics comes with a long history of preliminary conjectures later proven or disproved via experimentation. Brave champions pillared their beliefs before friend and foe alike with the simple desire to contribute. Those correct in their postulations live for eternity in textbooks, while those who fail ignobly disappear. Arthur Miller in his book Empire of the Stars dusts off the fairly recent instantiation of ideas and postulations surrounding black holes. In it he shows that even being correct may not necessarily add your name to the wall of physics fame.

Greetings, fellow SkyWatchers! Let's start the week off with one of the finest globular clusters for both hemispheres - M2. There's plenty in store as we explore history, take a look at planetary nebulae, seek out galaxies and hunt down open clusters. A pair of occultations will round out the week as we keep our eyes on the skies...

And find out what's up!

One of the main challenges of returning humans to the Moon will be how to deal with all that gritty, clingy moondust. Scientists believe that ultraviolet radiation charges individual grains of dust, giving them a static charge. NASA is studying individual grains of moondust returned by Apollo astronauts to how much charge they can build up, and the results have been surprising. Ultraviolet radiation can give a grain of moondust 10 times more charge than the theories had calculated.

Modern spaceflight is dependent on reliable computers to handle navigation, life support, and other functions. The problem is that radiation in space, such as cosmic rays can cause computer chips to calculate incorrectly. NASA is working a solution that would run multiple redundant computers to do the same calculation several times over and then vote on which is the correct result. If a cosmic ray caused one processor to make a mistake, the other processors would still be correct, and the error would be prevented.

Most geologists believe that the early history of our planet was an extreme, "hellish" environment, under constant bombardment from asteroids, and completely devoid of modern formations, like continents. Researchers from ANU disagree, and think they've found evidence that continents had already formed within the first 500 million years, and there was liquid water interacting with rocks. The Earth at that time might have looked remarkably similar to our current planet, complete with continents and oceans.

Astronomers have turned up 19 new gravitationally lensed quasars using photographs from the Hubble Space Telescope and the Sloan Digital Sky Survey (SDSS). 8 of these are what are known as "Einstein's Rings", where a nearby galaxy and a more distant quasar are perfectly lined up from our vantage point. The nearby galaxy acts as a lens to gravitationally focus the light from the quasar to magnify our view of it.

After 4 months of operation, Mars Express' MARSIS radar instrument has gathered a tremendous amount of data about the Red Planet. So far, the instrument has been focused on Mars' upper atmosphere, or ionosphere, which is the highly electrically conducting layer maintained by sunlight. ESA scientists are working develop the first conclusions about the nature and behaviour of how this region of Mars' atmosphere interacts with the planet and the surrounding environment.

More than half the stars in our galaxy are small, dim M-class stars. Until now, researchers looking for extraterrestrial civilizations have passed over them, since they probably don't give off enough light to support life. But SETI researchers now think that they might be good candidates after all. A planet in orbit around an M-class star would have billions and billions of years orbiting its slow-burning star for life to evolve.

An Ariane 5 rocket blasted off Thursday from Kourou, French Guiana carrying two satellites: Spaceway 2 broadcast satellite for DIRECTV, and the Telcom 2 communications satellite for PT Telekomunikasi Indonesia Tbk. The combined weight of the two satellites was more than 8,000 kg (17,500 pounds), making this the heaviest double payload ever launched.

NASA/Stanford's Gravity Probe B spacecraft recently wrapped up a year of gathering data about the Earth's gravity field. If Einstein was correct, the Earth's rotation should twist up our planet's gravity field like a vortex. Scientists at NASA and Stanford are now analyzing the mountains of data sent back by the spacecraft to detect any shift in its orientation, which would indicate this vortex of gravity.

Astrophysicists at Lawrence Livermore National Laboratory have developed a computer simulation that fails to support one of two major theories of star formation: the competitive accretion model. In this model, clumps form in hydrogen clouds which then collapse to form stars which compete with surrounding stars for material. The simulation showed that turbulence around the newborn star would prevent additional material from falling into the star.

NASA's Spirit Mars rover recently observed the Martian moon Phobos pass through Mars' shadow. When this event happens here on Earth, it's called a lunar eclipse, as the Moon darkens and then brightens again as it passes through our shadow. This "Phobal eclipse" lasted about 26 minutes, but Spirit was only able to capture images from the first 15 minutes.

This is the best photograph ever taken of Saturn's F ring shepherd moon Pandora, taken by the spacecraft on September 5, 2005. This tiny moon is only 84 kilometers (52 miles) across, and covered in grooves and small ridges. This indicates that it's probably coated in dust-sized material, which then fractures in places. Cassini was 52,000 kilometers (32,000 miles) from Pandora when it took this picture.

ESA's Integral gamma-ray observatory has discovered a new class of X-ray fast transient binary stars, which had gone undiscovered in previous observations. This new class of double stars systems always has a bright supergiant star with some kind of compact companion - like a black hole, neutron star or pulsar. It gives off energetic busts of X-rays which flare up quickly and then fade away. It's possible that the compact companion tangles up the supergiant's powerful solar wind with its gravity, and then feeds on it in bits and pieces.

This unique photograph, taken by NASA's Chandra X-Ray Observatory, contains not one, but two supernova remnants. The pair are known as DEM L316, and they're located in the Large Magellanic Cloud galaxy. The gas shell at the upper-left contains considerably much more iron, so it's probably the product of a Type 1a, triggered by the infall of matter from a companion star onto a white dwarf. The lower-right shell is a Type II supernova, the remains of a massive star that exploded a few million years into its short life.