Researchers have discovered fog just above Saturn’s moon Titan, indicating how methane cycles between the atmosphere and the surface of the moon.

Newly released images provide graphic evidence that repairs have transformed the Hubble Space Telescope into a brand new observatory. (p. 7)

Panel suggests how to get human spaceflight program off the ground. (p. 9)

An asymmetry that the standard model of particle physics may not account for hints at the existence of a new and massive elementary particle. (p. 7)

Violent interactions between planets may have played a key role in shaping the architecture of many extrasolar planet systems. The sun’s planetary system may have escaped or recovered from such a catastrophe. (p. 12)

Saturn’s moon Titan may harbor a prebiotic mix of chemicals similar to those present at the dawn of life on Earth.

At least once a second, a dim, elderly star somewhere in the cosmos turns into a thermonuclear bomb. Briefly outshining its home galaxy, the explosion, known as a type 1a supernova, unleashes the equivalent of 1028 megatons of TNT — enough energy to destroy an entire solar system. Astronomers have marveled at these cosmic firecrackers for centuries. But so far nobody has explained in detail how these supernovas explode. Now, theorists are on the verge of attaining that understanding — and just in time, because astronomers are observing type 1a supernovas with a new urgency. In fact, t... (p. 22)

An unusual group of green, pea-shaped galaxies may be nearby analogs of remote galaxies undergoing a high rate of star formation. (p. 8)

Astronomers propose a new explanation for the formation of the darkest galaxies in the universe.

Editor’s Note: A paper in the July 23 Nature reports on evidence for ammonia in the plume of water vapor and ice emanating from Saturn’s moon Enceladus, along with the probable detection of argon-40, raising the chances that Enceladus has (or had in the recent past) liquid water in its interior. Science News reported that finding in this story, originally posted in May. Swooping within 25 kilometers of Enceladus, the Cassini spacecraft has obtained additional evidence that the interior of this tiny, icy moon of Saturn may contain liquid water. Hunter Waite of the Southwest Res...

Images reveal that an object has recently bashed into Jupiter, 15 years after the first of 21 chunks of Comet Shoemaker-Levy 9 struck the giant planet and created a memorable display of dark spots, waves and plumes. (p. 8)

New simulations reveal that some of the first stars in the universe formed in pairs. (p. 7)

The existence of a small, elderly black hole places a new upper limit on the length of any extra dimension, a new study suggests. (p. 7)

Researchers unveil state-of-the-art simulation of galaxy formation. (p. 9)