Star blinks reveal secrets of Titan

Two stars far across the galaxy have helped scientists discover secrets of a world in our own solar system. Saturn’s biggest moon Titan – which is thought to resemble a primitive Earth – was observed as it passed in front of the distant stars.

The rare celestial alignments allowed astronomers to study winds in Titan’s thick atmosphere as starlight shone through it.

They discovered that Titan has its own fast moving jet stream blowing at 450mph more than 125 miles above its surface.

Bruno Sicardy, of Paris Observatory, organised expeditions to record the star blinks, called occultations, just seven and a half hours apart from different parts of the globe in 2003. His results, which appear in the Journal of Geophysical Research, are confirmed by results from Europe’s Hygens probe which parachuted to Titan’s surface in Jannuary 2005.

Sicardy said: “Titan’s atmosphere acts like a lens, so at the very middle of the occultation, a bright flash occurs. It is like the light falling through a glass of water and making bright patterns on the table.”

Analysing the shape of the flash of starlight showed that Titan’s atmosphere was flattened at the north pole because it was tilted away from the Sun and therefore cooler.

Titan, which is 3,200 miles wide, has been found to have mountains plus lakes and rivers of liquid methane. Scientists believe it resembles Earth as it was four billion years ago and so could be a new cradle for life.

Picture: This ESA artist’s impression shows the “light curve” produced by a star passing behind Titan, Saturn’s biggest moon.

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Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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