Post by Chicago Astronomer - Astro Joe on Mar 2, 2006 22:56:48 GMT -6
Telescopes 'worthless' by 2050
Ground-based astronomy could be impossible in 40 years because of pollution from aircraft exhaust trails and climate change, an expert says.
Aircraft condensation trails - known as contrails - can dissipate, becoming indistinguishable from other clouds.
If trends in cheap air travel continue, says Professor Gerry Gilmore, the era of ground astronomy may come to an end much earlier than most had predicted. Aircraft along with climate change will contribute to increased cloud cover.
"It is already clear that the lifetime of large ground-based telescopes is finite and is set by global warming," Professor Gilmore, from Cambridge's Institute of Astronomy, told reporters recently in London.
"There are two factors. Climate change is increasing the amount of cloud cover globally. The second factor is cheap air travel.
"You get these contrails from the jets. The rate at which they're expanding in terms of their fractional cover of the stratosphere is so large that if predictions are right, in 40 years it won't be worth having telescopes on Earth anymore - it's that soon.
Contrails often present little more than a transient nuisance to astronomers; but when certain weather conditions prevail, they can break to look like natural clouds.
Holger Pederson, an astronomer at the Nils Bohr Institute in Copenhagen, Denmark, who has studied contrails, explained: "You can recognise the jet contrails when they are young. So you can stop your observation and then restart as soon as the contrail has passed the field of view of the telescope.
Satellite imagery can be used to monitor contrail evolution. "Worse is when the contrails last for hours. Then they degrade into something you can hardly distinguish from natural cirrus clouds."
Dr Hermann Mannstein, of the German Aerospace Centre (DLR), agreed astronomy would become more difficult, but said there was an upper limit on the contrail problem.
Contrails form where the air is highly saturated with ice particles, but will not form if the air is too dry.
"You don't clog the whole sky. You have a certain proportion of the sky, in time and space, that can be affected," he said.
Full story here: news.bbc.co.uk/2/hi/science/nature/4755996.stm
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Will there actually be a day, (night), when all of our telescopes will be useless?... #confuse#