Scientists putting NASA's latest space telescope through its paces have found something odd - a pulsar emitting in gamma rays.

The discovery, published in this week's issue of Science, is the first finding from NASA's Fermi Gamma Ray Space Telescope, which was launched in June.

It solves a mystery uncovered by a predecessor telescope and offers an explanation to a host of similar unexplained phenomena.

The pulsar detected by Fermi is associated with a supernova remnant known as CTA 1, the remains of a massive star in the Milky Way galaxy that exploded about 10,000 years ago. It is located about 4600 light-years away in the constellation Cepheus.

These are known as pulsars, and their beams have been found in radio wavelengths, x-ray and, now for the first time, in gamma rays as well.