How much do you know about the millions of planetoids floating between Mars and Jupiter? We’ve got the facts for International Asteroid Day…
Happy International Asteroid Day! This annual event on June 30, endorsed by the United Nations, aims to raise awareness of the flying space rocks – from their scientific value to the dangers of an impact.
But how well do you know your minor celestial bodies? Here Meg Jorsh flies through a constellation of asteroid facts…
Birthday bonanza
The June 30 date was chosen to commemorate the largest asteroid impact in recorded history.
The Tunguska Event, on June 30, 1908, saw a stony planetoid 50 to 60m (160 to 200ft) wide explode over Siberia, Russia, levelling 2,150sq km (830 sq mi) of forest.
It burned up so fiercely in the Earth’s atmosphere, it didn’t even leave a crater.
Sounds like a blast
Long before that, a massive asteroid strike changed life on this planet for good.
The Chicxulub Event, 66million years ago, occurred when a rock 10km (6m) across slammed into the ground in modern Mexico, leaving a 200km (120m) crater.
It caused continent-sized wildfires, launching vast amounts of soot into the atmosphere and blocking out the sun.
The resulting climate chaos is believed to have wiped out the dinosaurs.
Ready to rock
Most of the asteroids in our solar system can be found in a belt that orbits the Sun between Mars and Jupiter. Around 1.6million have been catalogued, but there are thought to be many more.
The biggest is Vesta, with a 530km (329m) diameter, while the smallest are less than 10 metres (33ft) across. The total mass of all of them is less than that of Earth’s moon.
Hitting home
NASA is constantly monitoring the skies for signs of an impending asteroid strike. They say it is highly unlikely a rock big enough to cause widespread damage will hit Earth for the next 100 years or more.
However, smaller versions – roughly the size of a house – reach the planet every decade or so. They cause a bright fireball and a sonic boom loud enough to break nearby windows.
Highly illogical
The asteroids we know about are all given names – and they need to follow certain rules. That means one word if possible, inoffensive, original and up to 16 characters long.
The International Astronomical Union “strongly discourages” naming them after pets, but that didn’t stop stargazer James B. Gibson in 1971. He named his discovery – 2309 Mr Spock – after his cat.
Strike it rich
The asteroids are made up of the rocky leftovers from the birth of our solar system, 4.6billion years ago. Their structures vary – some of them have rings, or even tiny moons of their own.
Metallic asteroid 16 Psyche is thought to contain so much iron and nickel, it’s worth around $700 quintillion (£530 quintillion). That’s enough to make everyone on the planet a multi-trillionaire.