Rest assured, the Earth will not experience extinction on Tuesday, January 18. At 10:51 p.m. French time, the asteroid 1994 PC1 will flirt with the blue planet but keeping its distance. It will increase to 1.93 million kilometers, five times the extent between the Earth and the Moon. With a margin of error of 133 kilometers, the scientists admitted.
No collision is therefore to be feared. Nothing to do with the apocalyptic scenario of Don’t Look Up, the hit Netflix movie, in which two scientists desperately try to alert the world to the arrival of a planet-killing comet. For the next “visit” of this big rock, followed closely since 1974, it will be necessary to wait until January 18, 2105.
“It’s both an event and a non-event”, confirms Sylvain Bouley, planetary scientist, professor at the University of Paris Saclay and president of the Astronomical Society of France.
Why is 1994 PC1 considered “potentially dangerous” by NASA?
Because it will approach two million kilometers from the Earth and especially by its diameter: one kilometer. If we had an object of this size that encountered our planet, it would be quite catastrophic. In the specific case, there is no risk of collision.
Once past Earth, can he come back one day or another?
He is not lost forever. It is a well-known asteroid that orbits the Sun in just under two years. It thus crosses Earth’s orbit regularly and could be a potential danger in several centuries because close encounters with such an object are relatively rare.
Are there many asteroids in his case, under surveillance?
There are several thousand near-Earth asteroids, including several dozen or even hundreds of the size of 1994 PC1, which can potentially intersect Earth. But we have to put things into perspective: a collision with this type of object only occurs every ten or twenty million years.
The passage of 1994 PC1 is therefore to be taken both as an event and a non-event: two million kilometers is very far. Asteroids that graze the Earth, there are every day, and for some much closer. But they are generally only about ten meters in diameter. If we talk about this one in particular, it’s mainly because of its size.
How do you calculate the trajectory of an asteroid?
It only takes a few months of observation to know the orbit. But then it never happens at the whiteboard like in Don’t Look Up by posing the equations as Leonardo DiCaprio does. There are a whole bunch of computers that precisely check the data delivered by observation.
What is the risk of a “Don’t Look Up” scenario occurring?
It all depends on the size of the car. The film took as an example the asteroid which wiped out the dinosaurs and 75% of all forms of terrestrial life, 66 million years ago: it measured ten kilometers in diameter. An object of one kilometer will cause a regional, even continental upheaval. Below, these will be more local consequences.
But the smaller the object, the more frequent the risk of collision, every twenty to thirty years. The last major event occurred on February 15, 2013 in Chelyabinsk, Russia, with the explosion of a meteorite eighteen meters in diameter. The object fragmented in the atmosphere, there was no impact with the Earth. But the blast of fragmentation caused a shock wave that shattered the windows of houses and injured a thousand people.
To see the asteroid on Tuesday evening, it will be necessary to equip yourself with a telescope of at least six inches, because it is not bright enough to be seen with the naked eye. The Virtual Telescope Project will also allow it to be observed online.
In “Don’t Look Up”, the danger comes from a comet. What makes it different from an asteroid?
The asteroid is made of rock, mostly silica, and passes through the atmosphere quite easily. It is much more dangerous for the Earth than a comet, which is more porous, composed of more friable elements.
Asteroids, which are more numerous and generally larger than comets, come mainly from the main belt between Mars and Jupiter. When they are disturbed on their way, they become geo-cruisers like 1994 PC1. The origin of comets is much more distant, beyond Neptune.
Is it possible, as envisaged in the film, to deviate the trajectory of an asteroid or a comet?
With so many nuclear warheads, it’s a bit of science fiction. But today there is NASA’s Dart mission, launched in November 2021, which will send a small impactor crashing into the surface of an asteroid to see how it can be deflected. The space agencies are working very seriously on this.
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