Page last updated at 18:58 GMT, Wednesday, 27 August 2008 19:58 UK

First light for space telescope

Gamma-ray sky (Nasa/DOE/International LAT Team)
The map shows the sky as if viewed through gamma-ray glasses

A powerful Nasa space telescope launched in June has unveiled its first results - including an image of the sky viewed through "gamma-ray glasses".

Nasa also revealed a new name; the Gamma-ray Large Area Space Telescope has become the Fermi telescope.

The name honours Enrico Fermi - one of the pioneers of high energy physics.

Fermi will study some of the most extreme phenomena in the cosmos, which liberate massive amounts of energy in the form of gamma-rays.

It will scan the sky for massive cosmic explosions, giant black holes that hurl matter across space, and dense neutron stars with powerful magnetic fields.

In the two months since the telescope's launch, scientists have been testing and calibrating its two instruments, the Large Area Telescope (LAT) and the GLAST Burst Monitor (GBM).

Eye on the sky

The Large Area Telescope (LAT) scans the the entire sky every three hours.

During its first 95 hours of operation, the telescope generated a gamma-ray map of the sky similar to the one obtained by Nasa's now-defunct Compton Gamma-ray Observatory, which took years of observations to produce.

Fermi telescope (Nasa)
Fermi has now carried out its "first light" observations
The gamma-ray map of the sky from the LAT's "first light" observations shows the glowing gas of the Milky Way, blinking pulsars, and a flaring galaxy billions of light-years away.

The image shows gas and dust in the plane of the Milky Way glowing in gamma-rays as a result of collisions with accelerated nuclei called cosmic rays.

Familiar landmarks include the Crab Nebula, Vela and Geminga pulsars. Pulsars are fast spinning neutron stars, emitting powerful beams of radiation that sweep across the Earth's line of sight like lighthouse beacons.

They are formed when the core of a massive star collapses and matter is squeezed so tightly that an amount of material the size of a sugar cube would weigh more than one billion tonnes - about the same as Mount Everest.

Luminous core

Another bright spot in the LAT image lies some 7.1 billion light-years away, far beyond our galaxy.

Neutron star (Nasa/D. Berry)
A neutron star is the dense, collapsed core of a massive star
This is 3C 454.3 in the constellation Pegasus, a type of active galaxy called a blazar. It is now undergoing a flaring episode that makes it especially bright.

Active galaxies are galaxies with extremely luminous cores powered by monster black holes.

The spacecraft's secondary instrument, the GBM, spotted 31 gamma-ray bursts in its first month of operations. These high-energy blasts occur when massive stars die or when orbiting neutron stars spiral together and merge.

The telescope's new name honours Enrico Fermi, an Italian physicist who immigrated to the US and died in 1954.

He worked on the development of the first nuclear reactor and was awarded the Nobel Prize in Physics in 1938 for his work on radioactivity.

Lift-off for Nasa space telescope
11 Jun 08 |  Science/Nature
Nasa's eye on the 'violent cosmos'
10 Jun 08 |  Science/Nature
Probe studies 'extreme physics'
11 Jan 07 |  Science/Nature

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