Nobel prize in physics awarded for work on cosmology – as it happened
James Peebles, Michel Mayor and Didier Queloz honoured for ‘improving our understanding of evolution of universe and Earth’s place in the cosmos’
12.35pm BST
And there we leave the physics prize for another year. Huge congratulations go to James Peebles, who set the foundations for modern cosmology with his work on the big bang, dark matter and dark energy, and to Didier Queloz and Michel Mayor who spotted the first world beyond the solar system.
Here is my colleague Hannah Devlin’s news story on the prize:
Related: Nobel prize in physics awarded to cosmology and exoplanet researchers
12.21pm BST
There are two methods that astronomers use to spot planets around other stars. One is the so-called transit method where scientists watch for planets as they wander across the face of their parent star. Even though the star is but a pinprick in the heavens, sensitive telescopes can often detect the minuscule dimming of the starlight as the planet goes by and casts its shadow on the detector. It’s been extremely successful - Nasa’s Kepler’s mission is one space telescope that has exploited transits to find hoards of new planets.
Michel Mayor and Didier Queloz used a different technique. They looked at how stars are pulled around by planets that swing around them. This radial velocity method exploits the Doppler effect. In this case, as a planet’s gravity pulls its star towards Earth - with its telescope-wielding astronomers - light from the star is shifted towards the blue wavelengths of the electromagnetic spectrum. The rays are basically squeezed up, making them bluer. As the planet goes around the star and pulls it backwards, the starlight is stretched out and so turns more towards the red end of the electromagnetic spectrum. Measure these wavelength variations and you can work out first if there’s an unseen planet in orbit around a star, and secondly how long a year lasts on the world.
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