Physics and Astronomy

Satellites have detected the shifting forces that weave the Northern Lights.

A group of four spacecraft has given scientists their first glimpse of the immense electrical circuit above the Earth that creates the shimmering veil of the aurora borealis, or Northern Lights 1 .

In January 2001 the four satellites of the European Space Agency’s Cluster mission encountered a beam of electrons moving away from the Earth near the North Pole. The beam was on the outwa

American Geophysical Society Meeting, San Francisco, December 2001

The Sun’s violent outbursts have deep and twisted origins.

The Sun’s violent eruptions of material and magnetic energy have deep and twisted origins, researchers told this week’s American Geophysical Union Meeting in San Francisco, California.

These coronal mass ejections (CMEs) cause the aurora, seen at the Earth’s poles, and can knock out spacecraft. An understanding of what drives CMEs may one da

Mars’ polar ice caps are slowly melting.

The martian ice caps are shrinking. As they are made mostly of frozen carbon dioxide, this evaporation could trigger an increase in Mars’ own greenhouse effect.

Images from the Mars Global Surveyor spacecraft show that ice ridges and escarpments have retreated over the past two years or so. The orbiting probe has also captured the ice thickening and thinning with the passing seasons.

The reason for the change is not yet clea

In any computer’s hard drive, magnetic fields spin electrons this way or that. Now physicists have demonstrated that an electric field can do the same when applied to electrons in semiconductors. And unlike the older magnetic approach, their new device, called a spin gate, is capable of easily imparting a range of spin values. The team’s results, described in a report appearing today in the journal Nature, may one day help to scientists realize the ideal of spintronics—quantum computing based on ele

Astronomers from the University of Pennsylvania, in collaboration with an international team of researchers, have made the first direct detection and measurement of the properties of a dark matter object in the Milky Way.
This observation of a gravitational microlensing event — a temporary increase in the brightness of a background star during the time it takes dark matter to pass in front of it — is reported in today’s issue of Nature.

“By measuring its mass, distance and velocity, w

Hubble spots atmosphere on planet 150 light years away.

Astronomers have glimpsed the atmosphere of a planet in a solar system other than our own for the first time. The feat is a first step towards detecting planets capable of supporting life elsewhere in the Universe.

David Charbonneau, of the California Institute of Technology, Pasadena, and colleagues, pointed the Hubble space telescope at the planet, which lies 150 light years away in the constellation Pegasus. Of the 7