They are one of the most common sights in the sky. But sadly, they also generate one of the most common questions: “What is a shooting star?” And people are still wow-ed and amazed when they see a bright one, as if something incredible just happened! Well, you could say something incredible did just happen, but they happen more often than you realise, it’s just that you don’t get out and look up often enough to see them…which is why, dear reader, I’m here encouraging you to be more aware of what goes on above your head.
Falling stars, or shooting stars, are meteors, usually small bits of rock no bigger than a grain of rice that have met with the Earth and burned up with frictional heat created with colliding the gasses in the Earth’s atmosphere. I liken it to giving yourself a bad case of carpet burn, or rope burn (or any other sort of friction burn you may have painfully experienced). The heat of the molecules rubbing against each other gets so great an incandescent light is created and that’s the streak of light you see – the meteor.
The name meteor has it origin from the Greek language, where meteoros meant “high in the sky”. So meteors are things of the sky, studied by astronomers, but meteorologists study the weather, the movements of the sky above itself. This is because for many centuries philosophers, natural philosophers, then scientists, argued and debated on the origin of these streaks of light. Some thought they could have been caused by ignited gas from unseen floating plants! It wasn’t until the the great Leonid meteor storms of the 1800’s that astronomers began to admit that they had a celestial origin, and not until the break up of Comet Biela and the resulting meteor shower at it’s expected return in 1872 was it finally proved that comets were a major source of these bits of space junk.
The action happens about 80 km high, well above your roof tops, and well above where planes fly, too. The International Space Station, though, at 350km up, is right in the firing range of anything coming past, as is any other satellite in orbit. Yep, meteorites are a problem in space. They don’t get talked about a lot, but if you listen carefully, astronauts and space scientists will mention the technical headache they can cause from time to time.
What’s the difference between a meteor and a meteorite? A meteorite is a meteor that has hit the ground, and it would have to have been pretty big to start with to have survived the fall. How big? A good rule of thumb is if it lights the ground up like its full moon and you could read a book easily and it produces a sonic boom, then there is a good chance part of it survived to hit the ground. Don’t go chasing it – it’s probably further away than you realise – but there are people interested in the sighting, particularly if you are in Australia. I strongly encourage you to download and become familiar with the Fireballs in the Sky app, from the team with the same name. They are based at Curtin University in Perth, Western Australia, and have a network of cameras across the Nullarbor watching the night sky for potential falls. The more reports they get, the easier it is the triangulate the fall location. Daytime sightings are also special, as they have to be big to be bright enough to be seen during daylight.
So if you see a bright streak in the night sky, relax, enjoy the sight, and thank the planet you’re on for the thick layer of gas above your head that is protecting you from the hundreds of little hits that come our way every day.