In its relentless probing of Venus's atmosphere, ESA's Venus Express keeps revealing new details of the Venusian cloud system. Meteorology at Venus is a complex matter, scientists say.

New night-side infrared images gathered by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) in July 2006, clearly show new details of a complex cloud system.

New Hubble images have provided a dramatic glimpse of a large massive galaxy under assembly as smaller galaxies merge. This provides the best demonstration so far that large massive galaxies form by merging smaller ones.

This formation process has commonly been thought to be the way galaxies grew in the young Universe. New Hubble observations of the radio galaxy MRC 1138-262, nicknamed the 'Spiderweb Galaxy', have shown dozens of star-forming satellite galaxies in the actual process of merging. In nature spiders earn our respect by constructing fascinating, well-organised webs in all shapes and sizes.

NASA's Spitzer Space Telescope has made the first measurements of the day and night temperatures of a planet outside our solar system. The infrared observatory revealed that the Jupiter-like gas giant planet circling very close to its sun is always as hot as fire on one side, and potentially as cold as ice on the other.

"This planet has a giant hot spot in the hemisphere that faces the star," said Dr. Joe Harrington of the University of Central Florida, Orlando, lead author of a paper appearing online today in Science. "The temperature difference between the day and night sides tells about how energy flows in the planet's atmosphere. Essentially, we're studying weather on an exotic planet."

The Dawn project is deep into the testing phase of ATLO (Assembly, Test, and Launch Operations) with completion of all the Comprehensive Performance Tests demonstrating subsystem functionality, the successful completion of the Environmental Test Readiness Review held September 6-7, and the first major environmental test (Electromagnetic Interference/Compatibility) due to begin next week.

After EMI/EMC, the spacecraft undergoes acoustics and dynamics testing, then is shipped to the Naval Research Lab in Washington, DC for one month of testing (late Dec-Jan) in a large thermal-vacuum chamber. This chamber is large enough to allow a test-firing of the ion thrusters. After thermo-vac testing, the spacecraft ships directly to Cape Canaveral for launch, in a 20-day window that opens June 20, 2007.

The Dawn payload integration to the spacecraft was completed during September, and all of the science instruments have now been tested for functionality on both primary and redundant interfaces.

Integration went smoothly and all instruments checked out perfectly. As part of the comprehensive performance testing of the instrument systems, science data were transmitted from the spacecraft through the Dawn Science Center at UCLA to the instrument teams' home institutions.

With giant Saturn hanging in the blackness and sheltering Cassini from the sun's blinding glare, the spacecraft viewed the rings as never before, revealing previously unknown faint rings and even glimpsing its home world.

This marvelous panoramic view was created by combining a total of 165 images taken by the Cassini wide-angle camera over nearly three hours on Sept. 15, 2006. The full mosaic consists of three rows of nine wide-angle camera footprints; only a portion of the full mosaic is shown here. Color in the view was created by digitally compositing ultraviolet, infrared and clear filter images and was then adjusted to resemble natural color.

Scientists with Cassini mission have spied a new, continuously changing feature that provides circumstantial evidence that a comet or asteroid recently collided with Saturn's innermost ring, the faint D ring.

Imaging scientists see a structure in the outer part of the D ring that looks like a series of bright ringlets with a regularly spaced interval of about 30 kilometers (19 miles). An observation made by Hubble Space Telescope in 1995 also saw a periodic structure in the outer D ring, but its interval was then 60 kilometers (37 miles). Unlike many features in the ring system that have not changed over the last few decades, the interval of this pattern has been decreasing over time.

Cassini scientists are on the trail of the missing moons of Saturn. A recent observation by the spacecraft leads them to believe that they will find the moons near newly discovered rings around the planet.

During an unprecedented opportunity, with the sun poised behind Saturn, Cassini scientists discovered two new rings and confirmed the presence of two others. The new rings are associated with one or more small moons and share their orbits with the moons, while scientists suspect a moon is lurking near a third ring.

Saturn appears dressed to the nines, "wearing" a strand of "pearls" in a stunning infrared image from the Cassini spacecraft that showcases a meteorological phenomenon.

The image, acquired by Cassini's visual and infrared mapping spectrometer, shows Saturn lit by its own internal, thermal glow. Clearly visible is a 60,000-kilometer-long (37,000 miles) string of bright "pearls," which are actually clearings in Saturn's deep cloud system.

At the core of ESA's LISA Pathfinder mission sit two small hearts. Each is a cube, just 5 centimetres across. Together they will allow LISA Pathfinder to lay the foundations for future space-based measurements that investigate the very core of Einstein's General Relativity.

A cornerstone of relativity is the concept of a frame of reference. This is a set of bodies relative to which any motion can be measured. Without a reference frame, no motion through space can be detected. Scientists call a frame of reference 'inertial' if unperturbed objects appear in that frame, either at rest or moving at a constant velocity. For a reference frame to be perfectly inertial, the bodies that are used to mark it must be completely free of any force.

The highest wind speeds in Jupiter's Little Red Spot have increased and are now equal to those in its older and larger sibling, the Great Red Spot, according to observations with NASA's Hubble Space Telescope.

The Little Red Spot's winds, now raging up to approximately 400 miles per hour, signal that the storm is growing stronger, according to the NASA-led team that made the Hubble observations. The increased intensity of the storm probably caused it to change color from its original white in late 2005, according to the team.

Could all of the asteroids, comets, and planets in our Milky Way galaxy be made of a similar mix of dusty components?

After analyzing the dust particles of a variety of comets with NASA's Spitzer Space Telescope, the Deep Impact spacecraft, and the internationally funded Infrared Space Observatory, Dr. Carey Lisse, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., suspects that the answer is yes.

"Comets are the stepping stones to planets," said Lisse. "With these missions, astronomers know more about comets today than ever before, and we're still only beginning to scratch the surface."

More than 200 years ago, the philosopher Emmanuel Kant first proposed that planets are born from disks of dust and gas that swirl around their home stars. Though astronomers have detected more than 200 extrasolar planets and have seen many debris disks around young stars, they have yet to observe a planet and a debris disk around the same star.

Now, the NASA/ESA Hubble Space Telescope, in collaboration with ground-based observatories, has at last confirmed what Kant and scientists have long predicted: that planets form from debris disks around stars.

With stunningly powerful vision, the HiRISE camera on NASA's Mars Reconnaissance Orbiter has taken a remarkable picture that shows the exploration rover Opportunity poised on the rim of Victoria crater on Mars.

The High Resolution Imaging Science Experiment (HiRISE) camera detailed the entire 800-meter (roughly half-mile) Victoria crater and the rover -- down to its rover tracks and shadows -- in a single high-resolution image taken Wednesday (Oct. 3).

NASA's long-lived robotic rover Opportunity is beginning to explore layered rocks in cliffs ringing the massive Victoria crater on Mars.

While Opportunity spent its first week at the crater, NASA's newest eye in the Martian sky photographed the rover and its surroundings from above. The level of detail in the photo from the high-resolution camera on the Mars Reconnaissance Orbiter will help guide the rover's exploration of Victoria.