If you looked at the night sky late last week you probably saw a few more shooting stars than normal. When “stars fall as rain” as Chinese astronomers reported in 902 AD, appearing to come from one point in the sky, a meteor shower is taking place. In events such as this stars don’t actually fall. What we see are meteors, fragments left behind by comets that burn up and glow as they pass through the Earth’s atmosphere. Comets are small bodies of the Solar System composed of icy gas and dust. When a comet passes close to the Sun and heats up, some of its dusty-icy material evaporates creating a stream scattered along the comet’s orbital path. Comets such as Swift-Tuttle – the responsible for last week’s meteor shower – leave a stream that intersects the Earth’s orbit. As our planet travels around the Sun, it encounters the debris left behind by the comet at regular and predictable times and a meteor shower happens.
|photo: Mila Zinkova, Wikimedia Commons|