Quick Fire Science: Meteors
Star gazers have been peering at the night sky all this week looking for shooting stars, as the annual Perseid meteor shower has reached its peak. But what are shooting stars, and what's the best way to observe them? Here's Dave Ansell and Alex Parkyn-Smith with this week's Quick Fire Science.
- Shooting stars are flashes of light in the night sky that move rapidly and usually last for no more than a second or two.- They appear when pebble-sized pieces of space rock collide with the Earth.- The pebbles themselves are much too small to see, but as they enter the Earth's atmosphere they heat up and ionise the air around them, creating a glowing fireball.- This heat arises because of the tremendous speed that the pebbles are travelling at on impact -- tens of kilometres each second, and much faster even than satellites in orbit around the Earth.- Shooting stars can be seen every few minutes on any night...- ... but at certain times of year many more are seen, as the Earth travels through trails of debris left behind by comets.- Meteors that appear during these showers appear to shoot out of a particular direction in the sky, because they are all travelling in the same direction along the comet's orbit.- Meteor showers each have unique characteristics that depend upon the size and speed of the debris left behind by particular comets.- The Perseid meteor shower is one of the best known, because it reliably produces around 80 meteors an hour, and many are very bright.- If you're going out to observe, you don't need any special equipment. Just find a comfortable spot, stare at the sky, and wait.- But don't forget that it takes a few minutes for your eyes to adapt to the dark. Find the darkest place you can, and if the Moon's up, try to hide it behind a building.- If you're really lucky, you might see a fireball - exceptional meteors that can be as bright as the Moon and leave glowing trails behind them that persist for up to a minute.