NASA's Chandra X-Ray Observatory has taken a new photograph of SN 1006; a supernova that appeared in the sky in 1006, and blazed more brightly than Venus. We now know that SN 1006 announced the death of a star located approximately 7,000 light years from Earth. It's likely that a white dwarf star was siphoning matter away from a companion star. When its mass exceeded the limit of stability, it exploded.

A study of ice samples extracted from deep underneath Greenland's ice sheet could help scientists recognize methane-producing bacteria on Mars. ESA's Mars Express spacecraft recently turned up evidence of methane in the martian atmosphere. The source of this methane could be from a class of bacteria called Archaea. Although the best place to look for microbes would be from ice several hundreds of metres down, there should also be meteor craters where rock has been recently exposed.

Like all spiral galaxies, our own Milky Way has magnificent spiral arms. We're just inside the galaxy, so we don't get a good view of them. An international team of radio astronomers have revised the distance to the Milky Way's Perseus spiral arm. They used a simple method called triangulation, where the angles to various stars are measured when the Earth is at opposite sides of its orbit. The previous estimates are probably off because the stars are moving more quickly than astronomers realized, which added errors to the calculations.

This photograph shows two of Saturn's ring shepherd moons surrounded by halos of icy particles: Prometheus (at left) and Pandora (at right). Prometheus tugs at Saturn's rings pulling a stream of particles towards it as it orbits the giant planet. Cassini took this image on October 29, 2005 when it was approximately 459,000 kilometers (285,000 miles) from Pandora and 483,500 kilometers (300,500 miles) from Prometheus.

An international team of astronomers have analyzed a recent short gamma-ray burst, and they think it's the last scream of a neutron star being gobbled up by a black hole. The burst was discovered on July 24, 2005 by NASA's Swift satellite, and then astronomers performed followup observations with a variety of instruments. The length of the explosion and the wavelengths of radiation emitted have led astronomers to the conclusion that it had to be a neutron star colliding with a black hole.

Astronomers have discovered a dusty disk around a young star that could be in the process of forming new planets. The star, which is approximately the size of our own Sun, was observed using NASA's Spitzer Space Telescope. The star, known as HD 12039, is about 30 million years old; the age at which astronomers believe the terrestrial planets in our Solar System had nearly formed. Based on Spitzer's analysis to date, it looks like only 1-3% of young Suns have a disk like this surrounding them.

With Christmas approaching, I just wanted to give you a final reminder about the Year in Space 2006 calendar. This 144-page spiral-bound desk calendar has 53 full-colour space photographs, so you can gaze into infinity as you plan your week. It's filled with space trivia, sky events, daily Moon phases, and additional calendars. Universe Today readers can save at least 27% off the suggested retail price and pay only $10.95 USD by ordering online. There's free shipping in the U.S., and deeper discounts for multiple copies. Click here to visit their website.

Fraser Cain
Publisher
Universe Today

P.S. And congratulations to Andrea from Madison, Wisconson who won the calendar giveaway I did last week. Nice going!

Rick Gatley took this picture of a contrail shadow from Texas. This picture was taken the cockpit of a BeechJet 400A flying westbound at 40,000 feet over the Texas coast.

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.

Shahriar Davoodian took this picture of M42 on 8th December, 2005 from Damavand, Iran. Shahriar used Meade 8" LX90 with Canon EOS 300D camera.

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.

In this Cassini image, Saturn's rings cast dark shadows across the face of the giant planet. The three bright arcs in the image are the three well-known gaps in Saturn's rings: the Cassini Division, the Encke Gap and the Keeler Gap. Cassini took this image on October 29, 2005 when it was 446,000 kilometers (277,000 miles) from Saturn.

JAXA engineers are working hard to recover their ailing Hayabusa spacecraft. The spacecraft has been out of contact since December 9th, after it turned suddenly from a fuel leak. Hayabusa was supposed to return to Earth in June 2007, but JAXA is concerned that it won't have enough fuel to make this date, so they'll probably push the return back to 2010. Unfortunately, they have no way of knowing if Hayabusa actually retrieved a sample from Itokawa during its close encounter.

ESA's XMM-Newton observatory has turned up hot gaseous halos around several spiral galaxies. These ghostly veils have been seen surrounding "starburst galaxies", which are going through a tremendous amount of star formation - but not around the more common kinds of galaxies. Unlike a starburst galaxies, which concentrates their halos, regular galaxies will have simmering star formation stretching across them entirely. These halos can contain up to 10 million solar masses of gas.

An international team of astronomers have discovered a new large object in the Kuiper Belt; a region of the Solar System beyond the orbit of Neptune. The object's official designation is 2004 XR 190, but the discoverers are calling it "Buffy" for now. Buffy is approximately half the size of Pluto, and orbits the Sun roughly double the distance of Neptune. Although there are larger objects in the Kuiper Belt, Buffy has one of the most unusual orbits: 47-degrees off the plane of the ecliptic, where the other planets orbit.

NASA's Cassini spacecraft took this surprising photograph of Saturn's rings precisely edge-on. What's unusual is the strange bulge right at the edge of the rings. It's possible this bulge is created by a kilometer-sized chunk of material that's disrupting the ring material with its gravity. It could also be an effect of viewing the rings perfectly edge-on; normally faint material becomes visible when viewed at this angle.

The European Space Agency is developing a new thruster based on the same physics that power the northern and southern auroras. This new plasma thruster could eventually deliver more power than the efficient ion engines which have been installed on several spacecraft. ESA engineers calculate that a plasma engine could deliver several times more thrust from a similar sized ion engine, but still be as fuel efficient.

NASA's Spitzer Space Telescope has found more than 100 new star clusters hidden within the dusty areas of our own Milky Way. The powerful infrared observatory can see through the dark dust that normally obscures our view of this region of the galaxy. The team of astronomers that made the discovery found that there are twice as many clusters in the southern galactic plane (visible from the southern skies) as there are from the northern galactic plane. This may offer hints about the location of the Milky Way's spiral arms.

The brightest star in the nighttime sky is Sirius, aka the Dog Star. But did you know it has a white dwarf companion called Sirius B? Unfortunately, the light from this burned out star is washed out by Sirius' brilliant glow. Astronomers have been able to use the Hubble Space Telescope's sensitive instruments to isolate the light from Sirius B and measure its mass by how its gravity bends light emitted from the star. Even though it's only 12,000 kilometers (7,500 miles) across, Sirius B has 98% of the mass of our Sun.

On Earth we have the Northern and Southern Lights, and there's a similar phenomenon on Mars too. But instead of sticking to the planet's poles, these faint auroras can show up anywhere on the planet; wherever there are patches of strong magnetic fields. Over the past six years, NASA's Mars Global Surveyor has turned up 13,000 aurora events on the Red Planet, and mapped their locations. These mini magnetic fields can potentially protect the planet's surface from the Sun's solar wind.