Giant electrical circuits power the magical open-air light show of the auroras, forming arcs in high-latitude regions like Scandinavia. New results obtained thanks to ESA's Cluster satellites provide a new insight into the source of the difference between the two types of electrical circuits currently known to be associated to the auroral arcs.

The deep mechanisms that rule the creation of the beautiful auroras, or polar lights, have been the subject of studies that are keeping solar and plasma scientists busy since years.

A new theory to explain the high-energy gamma-ray emissions from collapsing stars has been put forward by an international team of researchers. Their results will be published shortly in the Monthly Notices of the RAS.

Long duration gamma-ray bursts (GRBs), first discovered in the 1970s, are the most explosive events in the Universe. Finding out what happens during these cataclysmic events is a major challenge, partly because they usually occur at the edge of the visible Universe and partly because the bursts last only a matter of seconds.

When a massive star runs out of fuel, it no longer has the energy to support its mass. The core collapses and forms a black hole.

Supernovae stand out in the sky like cosmic lighthouses. Scientists at the Max Planck Institute for Astrophysics and at the National Astronomical Institute of Italy have now found a way to use these cosmic beacons to measure distances in space more accurately. The researchers have been able to show that all supernovae of a certain type explode with the same mass and the same energy - the brightness depends only on how much nickel the supernova contains. This knowledge has allowed the researchers to calibrate the brightness of supernovae with greater precision.

Astronomers from the University of Virginia and other institutions have found that Enceladus, the sixth-largest moon of Saturn, is a “cosmic graffiti artist,” pelting the surfaces of at least 11 other moons of Saturn with ice particles sprayed from its spewing surface geysers. This ice sandblasts the other moons, creating a reflective surface that makes them among the brightest bodies in the solar system (Enceladus, itself a ball of mostly ice, is the single most reflective body in our solar system).

“Enceladus’ art is a work-in-progress, constantly altering the surfaces of other moons orbiting within this moon’s beautiful swirl of ice particles,” said Anne Verbiscer, a research scientist in the astronomy department at the University of Virginia and the study’s lead investigator.

Light has been shed on the dark parts of the Moon with experiments by University of Edinburgh researchers simulating billions of years of lunar evolution.

It is generally believed the Moon was created after an early, semi molten, Earth collided with a planet the size of Mars.

The collision was so great that the orbiting debris would have formed a so-called lunar magma ocean, or liquefied rock, up to several hundred kilometres deep that would have covered the Moon's surface.

Yet until now, it has remained a mystery as to how this magma ocean cooled and how the lunar landscape evolved into white highlands and dark valleys.

A giant elliptical galaxy seen in an image from the Hubble Space Telescope is the closest gravitational lens yet known, according to information released by the Hubble Heritage Project Tuesday (Feb. 6).

John Blakeslee, an assistant professor with the Department of Physics and Astronomy at Washington State University, working with colleagues from the University of Hawaii and the University of Durham in England, targeted the galaxy for a closer look by Hubble.

Elliptical Galaxy ES) 325-G004 in the Abell Cluster S0740. (Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) / Acknowledgment: J. Blakeslee (Washington State University))

A giant cloud half the size of the United States has been imaged on Saturn’s moon Titan by the Cassini spacecraft. The cloud may be responsible for the material that fills the lakes discovered last year by Cassini's radar instrument.

Cloaked by winter's shadow, this cloud has now come into view as winter turns to spring. The cloud extends down to 60 degrees north latitude, is roughly 2400 kilometers in diameter and engulfs almost the entire north pole of Titan.

The new image was acquired on 29 December 2006, by Cassini's visual and infrared mapping spectrometer (VIMS).