On the morning of June 30, 1908, the sky above Tunguska, Siberia, exploded.
The intense heat, together with the speed, generated intense air pressure that caused the asteroid to break apart. It left a bright fireball that one witness 64 kilometres away said made him feel like his shirt was on fire.
In the end, 2,072 square kilometres of forest were destroyed and 80 million trees levelled.
Good news: It’s unlikely.
Of course, there can’t be an absolute guarantee that a smaller asteroid wouldn’t impact Earth.
We got a dose of what a smaller one could do on Feb. 15, 2013 when a 20-metre piece of space rock exploded in the atmosphere over Chelyabinsk, Russia. Two minutes after it passed, an air blast shattered windows, injuring almost 1,000 people. Travelling nearly 70,000 km/h, it released energy equivalent to 30 Hiroshima bombs.
You can hear it in the video below.
One of the most talked-about asteroids of late is known as Apophis. This 300-metre-wide asteroid will come within 31,000 kilometres of Earth on April 13, 2029 (yes, it’s a Friday). While there’s no risk of it entering Earth’s atmosphere, it’s certainly a close shave.
‘You shouldn’t be losing sleep over it.’ – Peter Brown
Still, astronomers estimate that the chance is one in 100,000 that it will collide with Earth. While that may not sound so reassuring, let’s put it this way: astronomers are 99.99911 per cent sure it will never impact us.
“There certainly is a risk from asteroid impacts; it’s the only natural risk that we as a species have the ability to predict well in advance and mitigate against, entirely,” said Brown. “But I want people to keep it in context. You shouldn’t be losing sleep over it.
“There will be, some time within the next five to 10 years, an asteroid discovered, very small, that will impact the Earth, and we’re going to know about it a day or two in advance,” Brown said.
But, he said, it won’t pose much of a threat. It could be simply broken windows.
And while there are no Armageddon-like plans to blow up an asteroid yet, organizations conduct practise exercises to plan for one colliding with Earth.
The Chelyabinsk event also heightened awareness that Earth exists in a cosmic shooting gallery. Our solar system is full of leftover debris — big and small — from its creation. It was the worldwide coverage of Chelyabinsk — the most documented impact ever — that was the impetus for Asteroid Day.
“A year ago, the United Nations … determined that Asteroid Day would be a very good educational day for people to learn about our solar system, learn about our universe, learn about asteroids, and learn about our relationship with asteorids and with our universe,” Diane Murphy of Asteroid Day told CBC News.
The key, both Murphy and Brown said, is to not panic and realize that there are people working on it. No big ones are likely to slam into Earth and wipe us out.
And if you read about an asteroid that’s going to impact Earth, check your sources. NASA and other space agencies are reliable. Independent sources or blogs are not.
“The biggest danger is hype and people becoming scared over a non-lethal impact,” Brown said. “If it is really something to be concerned about, it will be well-known, well-publicized and unambiguous, and it won’t be on some website in eastern Europe.”