Scientists have produced the first-ever image of multiple planets orbiting a star other than our own. Researchers typically infer a planet’s presence -- usually through its gravitational influence on a star -- but this is the first time they have imaged three planets directly using the Keck and Gemini telescopes.

The star, HR 8799, is a “main sequence star,” in the prime of its life, fueled by nuclear reactions within its core, and it occurs 128 light years from Earth. The planets traveling around it have masses between five and 13 times that of Jupiter, with the smallest planet closest to its sun and the largest the farthest away.

Relatively little is known about Mercury, the innermost of the four terrestrial planets in our solar system. In 1975 the Mariner 10 spacecraft returned intriguing images that showed smooth plains covering large swaths of Mercury's surface. But scientists could not determine whether the plains had been created by volcanic activity or by material ejected from below the surface when objects had collided into it. Thus, they could not reach a consensus over Mercury's geologic past. The new MESSENGER space mission has found evidence of past volcanic activity.

Scientists have analyzed a "light echo" from the original explosion of Cassiopeia A, the youngest known supernova in our own Milky Way galaxy.

The explosion occurred around 1680 -- just yesterday, in stellar terms.

The scientists observed an infrared spectrum of radiation that suggests Cassiopeia A was a type IIb supernova and was birthed from the collapse of a red supergiant star.

NASA's Spirit rover has detected silica-rich deposits on Mars, researchers reported in a study that provides the data and analysis underlying this discovery.

Extensive deposits of nearly pure silica – either as quartz or opal – are typically signs of geochemical processes that involve water.

The findings lend support to the idea that relatively large amounts of liquid water once existed on Mars.

Artist's impression of HD 189733b

By identifying the "chemical fingerprints" -- organic molecules found in a planet's environment -- scientists can begin to locate "habitable zones" in exoplanets (planets outside our solar system). These zones are defined by their chemical composition, temperature, and pressure, all of which are necessary for the possibility of life.

The detection of water and methane in the atmosphere of the Jupiter-sized gas giant, HD 189733 b, may open the door to a deeper and more localized analysis of other more promising exoplanetary environments, scientists say.

Phoenix Mars Lander on course for May 25 touchdown.

The Atacama Large Millimeter/submillimeter Array, also known as ALMA, is one of the world's largest ground-based astronomy projects and a major new facility for world astronomy. Built in the Atacama desert in Chile, the project will include 80 high-precision telescopes. The ALMA project is an international collaboration between Europe, Japan and North America in cooperation with the Republic of Chile.

Gamma-ray bursts are short-lived events, lasting between a few milliseconds to a few minutes. The brightest of them emit more energy in a few seconds than our Sun will emit in its whole 10 billion-year lifetime. Gamma ray bursts occur several times daily somewhere in the universe. These fleeting explosions are precursors to the births of black holes.

Gamma-ray bursts are detected by orbiting satellites about two to three times per week. Since its launch in 2004, the Swift satellite has discovered over 292 gamma-ray bursts, and pin-pointed a further 320 bursts detected by other satellites. Swift's rapid response - it was named after the bird, which catches its prey "on the fly" - has been critical to understanding these titanic events.

The Spitzer Space Telescope, trained on the star AA Tauri, has revealed traces of abundant water and simple organic molecules in the inner disk of dust and gas surrounding the very young star thought to be similiar to our early sun.

Using thermal emission observations from NASA's Odyssey spacecraft, scientists have mapped seasonal changes in the temperature of the Martian surface to locate the planet's ice water. The findings, which were reported in the journal Nature, indicate that the depth of the water ice table varies greatly over small-scale patches on the Red Planet.

Scientists say the findings show how the water cycle is working on Mars, and that the cycle is probably quite active today.