Shooting Star

Shooting stars, or meteors, are caused by tiny specks of dust from space. These particles burn up 65 to 135 km above Earth’s surface as they plunge at terrific speeds into the upper atmosphere, making the air glow as they pass.

If Earth moves at 29 km/s around the Sun, these bits of dust are travelling at about 40 km/s. When they enter our atmosphere they have a combined speed of 30 to 70 km/s (100,000 to 250,000 km/h), depending on whether or not they meet it head on! The meteors we know as the Perseids enter the Earth’s atmosphere at 60 km/s.

By comparison, the International Space Station moves at “only” 8 km/s in its orbit; capsules returning to Earth with astronauts on board enter the atmosphere at a similar speed.


A constant meteor shower

Our solar system is full of dust, which constantly comes into contact with Earth on its voyage around the Sun. This is the source of so-called “sporadic” meteors, a background phenomenon that produces about 10 shooting stars an hour.

However, there are parts of space where the dust is much denser. These clouds of miniscule debris are left behind by comets that break up as they repeatedly pass near the Sun. Earth passes through some of this dust around the same dates every year. The result is a meteor shower, a sudden spike in the number of shooting stars.Meteor showers are generally named after the region of the sky (i.e. the constellation) where they seem to originate – in other words, the constellation where the radiant of the meteor shower is located. Because of a trick of perspective, the dust that Earth encounters as it moves around the Sun seems to come from the same vanishing point, in much the same way that snowflakes appear to be coming at you from a “tunnel” when you are driving through a snowstorm at night.