Learning English - Words in the News
11 August, 2004 - Published 16:09 GMT
Astronomers are predicting that this week’s annual meteor shower -- known as the Perseids -- could be one the best ever. The shooting stars come about as the earth revolves through a comet's debris. This report from Owen Clegg:
As interstellar dust and debris crashes into the earth's upper atmosphere, it burns up in an intense streak of light across the night sky.
No meteor shower is more spectacular than the annual Perseid showers which astronomers consider one of the most rewarding sky watching events of the year. The showers, named after the constellation Perseus, happen as our planet crosses through the stream of debris left behind by the comet Swift-Tuttle.
The particles, most no larger than grains of sand, crash at up to fifty kilometres per second, where they burn up as shooting stars. The conditions are particularly good this year, because the moon is new and giving off little light -- allowing the Perseids free range to shine against the night sky.
In recent years, scientists have been more concerned with the earth colliding with comets and asteroids and comet Swift-Tuttle is big, about the same size as the asteroid that wiped out dinosaurs sixty-five million years ago. But calculations on the comet's trajectory show there's no danger of a collision for at least a millennium and probably much longer.
Owen Clegg, BBC.
an intense streak of light