Washington, Feb 12 - Climate change combined with human activity caused the disappearance of tropical rainforests in central Africa 3,000 years ago, a study has found.

According to the Prensa Latina news agency, an analysis of marine sediment of the Congo river shows that at that time there was the influence of a strong chemical erosion.

Experts from the French Research Institute for Marine Exploration (IFREMER) said this deterioration occurred with the arrival of tribal communities that brought agricultural and cast iron technologies to the region that is now known as Cameroon and Nigeria.

Washington, Feb 11 : A spacecraft orbiting Venus has revealed that Earth's cloud-covered neighbour is rotating a little slower than previously measured.

Peering through the dense atmosphere in the infrared, the ESA's Venus Express spacecraft found surface features were not quite where they should be.

Using the VIRTIS instrument at infrared wavelengths to penetrate the thick cloud cover, scientists studied surface features and discovered that some were displaced by up to 20 km from where they should be given the accepted rotation rate as measured by NASA's Magellan orbiter in the early 1990s.

Washington, Feb 11 : Using high-powered lasers, scientists have found that molten magnesium silicate undergoes a phase change in the liquid state, abruptly transforming to a more dense liquid with increasing pressure.

The research by Lawrence Livermore National Laboratory and collaborators provides insight into planet formation.

"Phase changes between different types of melts have not been taken into account in planetary evolution models," said lead scientist Dylan Spaulding, a University of California, Berkeley graduate student who conducted most of his thesis work at the Laboratory's Jupiter Laser Facility.

Washington, Feb 9 : New images of a neighbouring dwarf galaxy have revealed a dense stream of stars in its outer regions, the remains of an even smaller companion galaxy in the process of merging with its host, researchers say.

The host galaxy, known as NGC 4449, is the smallest primary galaxy in which a stellar stream from an ongoing merger has been identified and studied in detail.

Washington, Feb 9 : The giant black hole at the centre of the Milky Way may be vaporizing and devouring asteroids, which could explain the mysterious X-ray flares detected over a period of several years, a new study has revealed.

For several years NASA's Chandra has detected X-ray flares about once a day from the supermassive black hole known as Sagittarius A-star, or "Sgr A-star" for short.

The flares last a few hours with brightness ranging from a few times to nearly one hundred times that of the black hole's regular output. The flares also have been seen in infrared data from ESO's Very Large Telescope in Chile.

Washington, Feb 5 - NASA has received 6,372 applications for its 2013 class of astronauts, double the usual number, the US space agency said.

Only in 1978, when applications surged to more than 8,000, have more people expressed interest in joining the Astronaut Corps, NASA said in a statement.

The agency announced in November that it was looking for new recruits to staff planned missions to the International Space Station and to help develop the Orion spacecraft for renewed exploration beyond earth's orbit.

The application period closed Jan 27.

Washington, Feb 3 : NASA's Hubble Space Telescope has captured a uniquely close-up view of the brightest distant "magnified" galaxy discovered yet in the universe.

This observation provides a unique opportunity to study the physical properties of a galaxy vigorously forming stars when the universe was only one-third its present age.

A so-called gravitational lens is produced when space is warped by a massive foreground object, whether it is the sun, a black hole or an entire cluster of galaxies.

Washington, Feb 3 : The latest version of NASA's Clouds and the Earth's Radiant Energy System (CERES) instrument is scanning Earth for the first time, helping to guarantee sustained availability of measurements of the energy leaving the Earth-atmosphere system.

The CERES results help scientists to determine the Earth's energy balance, providing a long-term record of this crucial environmental parameter that will be consistent with those of its predecessors.

Washington, Feb 3 : Scientists have discovered a potentially habitable super-Earth orbiting a nearby star.

The star is a member of a triple star system and has a different makeup than our Sun, being relatively lacking in metallic elements.

This discovery demonstrates that habitable planets could form in a greater variety of environments than previously believed.

The international team of scientists led by Carnegie's Guillem Anglada-Escude and Paul Butler used public data from the European Southern Observatory and analyzed it with a novel data analysis method.

Washington, Feb 2 : A strong follow-up solar flare, which cropped up on Friday, just days after the Sun launched the biggest coronal mass ejection (CME) seen in almost a decade, delivered a powerful radiation punch to Earth's magnetic field even though it was targeted away from our planet, a new study including Indian origin scientist has revealed.

Washington, Feb 1 : Researchers have now captured the best and most complete glimpse of the material that lies so far outside our solar system.

A great magnetic bubble surrounds the solar system as it cruises through the galaxy. The sun pumps the inside of the bubble full of solar particles that stream out to the edge until they collide with the material that fills the rest of the galaxy, at a complex boundary called the heliosheath.

On the other side of the boundary, electrically charged particles from the galactic wind blow by, but rebound off the heliosheath, never to enter the solar system.

Washington, Jan 31 : Scientists have spotted vast clouds of hot gas `sloshing' in Abell 2052, a galaxy cluster situated nearly 480 million light years from Earth.

The scientists are studying the hot (30 million degree) gas using X-ray data from NASA's Chandra X-ray Observatory and optical data from the Very Large Telescope to see the galaxies.

"The X-ray images were amazing. We were able to see gas sloshing like liquid in a glass," said NRL's Dr. Tracy Clarke.

"Of course this would be one enormous glass since we see the gas sloshing over a region of nearly a million light years across!"

Washington, Jan 31 - A teacher from Maharashtra in India has been chosen for the US Space Foundation's elite 2012 Flight of Teacher Liaisons programme.

Vandana Suryawanshi of Vidya Valley School in Maharashtra is a middle school educator who has been teaching biology, earth science and general science for 20 years. He joins 19 other outstanding educators selected for their active promotion of space and science education.

The new flight of Teacher Liaisons will serve as advocates for space-themed education across the curriculum and will use Space Foundation-provided training and resources to further integrate space principles into the classroom, the Colorado Springs based non-profit leader in space awareness activities, educational programmes announced.

Washington, Jan 28 : Researchers believe recent discoveries made in some underwater caves in the Bahamas could provide clues about how ocean life formed on Earth millions of years ago, and perhaps give hints of what types of marine life could be found on distant planets and moons.

The finding is a result of teamwork between researchers at Texas `n' M University at Galveston and Penn State University.

Washington, Jan 28 : Moral imagination is a necessary faculty for workers who must overcome the stigmas of ethical conflicts and social rejection associated with certain types of jobs, a new study has revealed.

According to the study carried out at the Universidad Carlos III of Madrid (UC3M), there are some jobs ("dirty work", in Anglo-Saxon terminology) that, because of their characteristics, produce a certain amount of social rejection towards the people who perform them, due to the fact that they are subjected to moral conflicts and ethical decisions related to performing those duties.