Mile-wide asteroid gives Earth a near miss

Fireball: The large asteroid (52768) 1998 OR2 passed by Earth last week. © iStockPhoto

Are asteroids our biggest threat? Several giant space missiles passed us by recently – and scientists are coming up with amazing plans to protect the planet from intergalactic impact.

Last week, a giant rock, over a mile wide, passed close to Earth. Nasa described the object, which flew 10 times faster than a bullet, as “potentially hazardous”. In the words of Times writer Katie Gibbons: “it flouted galactic social distancing guidelines”.

Luckily for us, a “close shave” in astronomical terms means 3.9 million miles away – more than 16 times the distance between us and the Moon.

And Paul Chodas, the manager of Nasa’s Centre for Near-Earth Object Studies, has reassuringly said, “There are no asteroids which have any significant chance of hitting the Earth that are of any significant size.”

Indeed, Nasa scientists believe they know in advance about 90% of the near-Earth asteroids big enough to cause serious problems for humanity.

But that still gives room for some to go unnoticed.

On Monday, another space rock, which no one had tracked, flew just 4,000 miles above the Pacific Ocean. Fortunately, it was only the size of a truck.

But what would happen if a larger object slipped past the telescopes?

Anything a mile or so across, hitting the Earth at speeds of up to 30,000 miles per hour, would cause incomparable damage.

The dust coughed up from the ground would black out the Sun. Very little life would survive. We would probably become like the dinosaurs: extinct.

To protect Earth from such an event, scientists have come up with a few truly ingenious plans.

Some scientists say we could spray-paint an approaching asteroid white, so that the Sun reflects off one side more than the other, slowly diverting it off-course.

Others suggest we could fly a spaceship alongside it, using the laws of gravity to take it slightly off course.

If it is too close to try anything subtle, we could just fly a spaceship into it or, better still, attack it with a nuclear missile. This would splinter it into fragments. Being hit by lots of smaller rocks is better than being struck by one big one.

So, are asteroids our biggest threat?

Big bump

Yes. Though unlikely, an asteroid could destroy human civilisation overnight. In 2019, Nasa’s Office of Planetary Defence admitted that an unseen asteroid suddenly coming straight for Earth is still a real threat. This is why many organisations are committed to developing strategies to protect our planet. Something being unlikely doesn’t mean we should ignore its possibility.

No. There is a vanishingly small probability that a civilisation-ending space rock will hit our planet. We should focus on other, more likely, disasters. Preparing ourselves for the next pandemic could be one idea. Reducing carbon emissions is another. We could also discard the huge arsenal of apocalyptic nuclear warheads dotted across the world – except for those we would shoot at an asteroid of course.

You Decide

  1. Have you ever thought of an asteroid as being a serious threat before?
  2. Do you think that governments should spend more time and money protecting us from asteroids?

Activities

  1. On a piece of paper, design your own asteroid defence system.
  2. Do some maths to understand the size of space. Remember, 3,900,000 miles is a near miss when it comes to asteroids. Earth is 7,900 miles across. Grab the smallest object you can find, pretend it is Earth and measure it. Then use the same scale to place another tiny object the equivalent distance away. That’s the asteroid.

Some People Say...

“I despise the Lottery. There’s less chance of you becoming a millionaire than there is of getting hit on the head by a passing asteroid.”

Brian May, lead guitarist of the band Queen, and an astrophysicist

What do you think?

Q & A

What do we know?
Next year, Nasa will fly a spaceship into an asteroid to see how much this will change its trajectory. The project, called DART will test the technologies we may one day need to save the world. Russian scientists have recently explained the mysterious “Tunguska event” of 1908 as being an asteroid that skimmed the planet and then bounced back into space. The explosion flattened around 80 million trees across an area of 80 square miles in Siberia.
What do we not know?
Space has so many objects flying around that it is very hard to track all of them at once. “Our most important task is finding them and getting a fuller catalogue of everything that’s out there, so we don’t get surprised,” says Lindley Johnson, Nasa’s planetary defence officer.

Word Watch

Nasa
Established in 1958, the National Aeronautics and Space Administration is an independent agency of the US government responsible for, amongst other things, sending people to the Moon and studying the galaxy.
Hazardous
Risky, dangerous. A hazard is something that gets in your way, that might trip you up or hurt you.
Flouted
Going against or disregarding a rule. Often with an attitude of defiance. For example , if you don’t even try to hide that you are breaking the law.
Nuclear
A nuclear weapon has a devastating potential to cause damage. A few countries around the world have them.
Discard
Get rid of (someone or something) as no longer useful or desirable.
Arsenal
A collection of weapons and military equipment.

Subjects

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