What’s Up This Week – November 7 – November 13, 2005

Greetings, fellow SkyWatchers! “It is a most beautiful and delightful sight to behold the body of the Moon.” Take Galileo’s words to heart and be sure to let Venus and Mars capture the eye this week. Come, now. Let’s explore and observe some of the finest moments in astronomy history as we ask for the Moon…

But keep reaching for the stars.

10th Planet has a Moon

The newly discovered 10th planet – which the discoverers have dubbed “Xena” – appears to have a moon of its own. Nicknamed “Gabrielle”, this moon is 100 times fainter than Xena, and seems to orbit the planet once every couple of weeks. It’s estimated to be 1/10th the size of Xena, so approximately 250 km (155 miles) across. The powerful Hubble Space Telescope will be turning its gaze on the pair in November/December, and should reveal even more details.

Asteroid Ceres Could Have Large Amounts of Water

New observations from the Hubble Space Telescope indicate that the largest asteroid in the Solar System, Ceres, might have huge reserves of water ice under its surface. Ceres is approximately 580 miles (930 kilometers) across, and resides with many other asteroids in a belt of material between Mars and Jupiter. Ceres’ crust shows evidence of water-bearing minerals. In fact, if Ceres is 25% water, it would have more fresh water than what we have here on Earth.

Saturn’s Rings Have an Atmosphere of their Own

Saturn’s rings are separate from the planet they circle, and then even have an atmosphere of their own. During several flybys, Cassini has been able to detect very small amounts of molecular oxygen floating around the rings. Molecules of water are broken apart by ultraviolet light from the Sun; the hydrogen and some of the oxygen is lost into space, and some of the oxygen is frozen back into the rings. But there’s enough of a cloud of these atoms around the rings that this process must be ongoing and kept in a continual balance.

Largest Core in an Extrasolar Planet

Astronomers have found an extrasolar planet that contains the largest core ever seen in a planet. This planet orbits the Sun-like star HD 149026, is roughly the size of Saturn, and takes only 2.87 days to complete its year. The planet was first discovered by the effect of its gravity around its parent star. Astronomers were then fortunate to detect how much it dims the light from the star as it passes in front. From this information, they were able to measure the planet’s size, and calculate the size of its core. This discovery adds evidence to the “core accretion” theory of planetary formation, where planets start as balls of rock and ice, and collect a gas envelope around themselves.

Just How Earthlike is this New Planet?

When the recent discovery of a planet orbiting Gliese 876 was announced by astronomers, much of the interest focused on how “Earthlike” it is. So, just how like our home planet is it? Well… not very. For starters, the planet orbits only .021 the distance from the Earth to the Sun, and whips around its star once every 2 days. It has 6-8 times the mass of the Earth, so the gravity would be crushing for any potential life, not to mention the terrible radiation exposure from being so close to its parent star.

Amalthea is Just a Pile of Icy Rubble

By studying data gathered by NASA’s Galileo spacecraft, researchers have come to the conclusion that Amalthea, one of Jupiter’s moons, is probably just a jumble of icy rubble, held together by gravity. Scientists originally believed it was made of rock, but Galileo helped to discover that its density is actually lower than water. It probably formed further out in the solar system, but was then captured into a stable orbit by Jupiter’s immense gravity.

Did Life Arrive Before the Solar System Even Formed?

The theory of panspermia proposes that life really gets around, jumping fron planet to planet – or even from star to star. Life might be everywhere! Assuming this is true, how do single-celled bacteria make the journey through the vacuum of space? Easy, they use chunks of rock as space ships, in a process called lithopanspermia. And now, researchers from Princeton and the University of Michigan think that life carrying rocks might have been right there at the beginning of our solar system, keeping their tiny astronauts safe and sound, frozen in statis until the planets formed and the right conditions let them thaw out, stretch their proteins, and begin a process leading from microbe to mankind.

Mini Solar System Around a Brown Dwarf

NASA’s Spitzer Space Telescope has found the dusty disc of planetary material surrounding an extremely low-mass brown dwarf. The failed star, called OTS 44, is only 15 times the mass of Jupiter, and is located 500 light-years away in the Chamaeleon constellation. Previously, the smallest brown dwarf known to have such a disc was twice as massive. Astronomers are now wondering if a habitable world could form around such a small, dim dwarf.

Digging on Mars Won’t Be Easy

Because of the tremendous distance to Mars, human explorers will probably process local materials to get their air, fuel, and even building supplies. But extracting resources from the Red Planet is going to be hard, especially when the environment is so hostile. Scientists are studying how the dry Martian soil will likely behave in the low gravity and air pressure, to help engineers build equipment that can dig and move dirt. NASA’s upcoming Phoenix lander will help put some of this research to the test when it arrives on Mars in 2008; it will be digging trenches about a half-metre deep (20 inches).