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Cloud chasers studying Saturn's moon Titan say its clouds form and move much like those on Earth, but in a much slower, more lingering fashion.

Their forecast for Titan's early autumn -- warm and wetter.

Scientists with NASA's Cassini mission have monitored Titan's atmosphere for three-and-a-half years, between July 2004 and December 2007, and observed more than 200 clouds. They found that the way these clouds are distributed around Titan matches scientists' global circulation models. The only exception is timing -- clouds are still noticeable in the southern hemisphere while fall is approaching.

As summer changes to fall at the equinox in August 2009, Titan's clouds are expected to disappear altogether. But, circulation models of Titan's weather and climate predict that clouds at the southern latitudes don't wait for the equinox and should have already faded out since 2005. However, Cassini was still able to see clouds at these places late in 2007, and some of them are particularly active at mid-latitudes and the equator.

Titan is the only moon in our solar system with a substantial atmosphere, and its climate shares Earth-like characteristics. Titan's dense, nitrogen-methane atmosphere responds much more slowly than Earth's atmosphere, as it receives about 100 times less sunlight because it is 10 times farther from the sun. Seasons on Titan last more than seven Earth years.

Scientists will continue to observe the long-term changes during Cassini's extended mission, which runs until the fall of 2010. Cassini is set to fly by Titan on June 6.

Orion’s red supergiant Betelgeuse has been steadily shrinking over the last 15 years.

Betelgeuse is so big that if placed in our Solar System it would extend to the orbit of Jupiter. But thanks to long term monitoring by Berkeley’s Infrared Spatial Interferometer (ISI) at Mt Wilson, measurements of the star’s diameter reveal the giant to be shrinking. Over the last 15 years, the star has shrunk by more than 15 percent, equivalent to the same diameter as the orbit of Venus.

Despite its diminished size however, there is no evidence to suggest that the star is dimming. But we do not know why the star is shrinking.

Since the star’s size depends on the wavelength of light used to measure it, it is difficult to compare measurements. Tenuous gas in the outer regions of the star emits light as well as absorbs it, which presents a challenge in determining the edge of the star.

Comet dust caught in the upper reaches of Earth's atmosphere and scooped up by a NASA aircraft had been found to contain grains of dust dating back to before our Solar System formed. Dust like this is worth its weight in gold for telling us about the original conditions in the solar nebula that formed the planets.

The dust is from comet 26P/Grigg-Skjellerup, which last passed through the inner Solar System in 2002. A year later, Earth itself passed through the trail of the comet, and the NASA aircraft climbed to catch the dust. It was then handed over to a consortium of UK, US and German astronomers who found various chemical treasure troves, including in one dust particle four grains of silicate material that date back to before the formation of the Sun.

Using NASA's Spitzer Space Telescope to study white dwarf stars, astronomers have found the dusty remains of ancient solar systems.

White dwarfs are the dense glowing embers of Sunlike stars. While their atmospheres should consist entirely of hydrogen and helium, they are sometimes contaminated with heavier elements like calcium and magnesium.These metals really shouldn't be there.That means they are external pollutants.

The rocky debris imaged by Spitzer probably represents the innermost planets of a solar system that were ripped apart by the gravitational forces of their host star at the end of its life. Extrapolating our own Sun's life into the white dwarf phase, simulations show that the Earth may not survive, but that Mars and asteroid belt would probably lie outside of the Sun's grasp.

Perhaps the most exciting and important aspect of this research is that the composition of these crushed asteroids can be measured using the heavy elements seen in the white dwarf. In one case 17 heavy elements were found in one star, yielding a composition that closely matches the equivalent of a combined Earth and Moon. The next step will be to search for those ingredients that may suggest that life-bearing planets may once have existed in these systems.