On Monday, Feb. 29, around 18:45, many lucky people in Scotland and the north of England witnessed something spectacular. A bright light streamed across the sky, flashing several times before fading away. You could see it as far north as Shetland and Orkney, and as far south as Newcastle. Many people posted their camera recordings online, allowing millions to see it around the world.
Was it a UFO? Was it a piece of high-tech military technology? No and no. This was a rock from space colliding with the Earth’s atmosphere. The solar system is full of this kind of debris: bits of rock and ice left over from the formation of the planets some five billion years ago, or chipped off asteroids during more recent collisions in space. The Earth encounters and sweeps up this debris all the time.
Most common are the small specks up to the size of a grain of sand that produce brief flashes of light—a shooting star or meteor—when they encounter the Earth’s atmosphere and burn up. If you stand outside and watch the sky on a clear dark night, you should be able to spot several of these every hour. If you’re really lucky you might see a meteor shower, when the Earth is moving through the path of a comet that has left a trail of dust and rock behind after its icy material has been evaporated away by the sun’s heat.
Fireball February
When larger pieces of space debris such as the Scottish one stray into the Earth’s atmosphere, they produce more spectacular meteors as they burn up. These are known as fireballs or “bolides.” Judging from the footage online, Scotland witnessed one of about 10cm in diameter. It will have been moving at roughly 30km/second, burning up from the friction with the air as it plunged through. Some of the recordings show it breaking into dozens of smaller pieces before finally fading away. Sometimes this can produce meteorites—bits of rock that manage to survive their fiery descent and hit the ground—but apparently not in this case.
