If you’re wondering if a massive asteroid is going to hit Earth this week (or any time soon), thanks to headlines referring to a ‘planet killer’ space rock that’s going to come close to Earth, you can sleep easy.
This asteroid — named 2022 AP7 — is interesting for its discovery, but hardly about to tear Earth asunder.
Asteroids measuring more than a kilometre in diameter are automatically dubbed with this ominous title. But read beneath the headlines and you’re likely to find far more comforting facts.
Such as this one: among the three large, near earth asteroids (NEAs) discovered in a study published in The Astronomical Journal this week, two circle the sun completely interior to Earth’s own orbit.
It’s a bit like watching Formula One cars drive around a racetrack from the plush surrounds of a corporate tent. Being mown down by Max Verstappen or Lewis Hamilton might kill you, but those cars would need to jump the barriers and successfully drive over to your table.
One of the asteroids is noteworthy
2022 AP7 is the largest NEA discovered yet.
Unlike the other two (named 2021 LJ4 and 2021 PH27) circling the Sun on Earth’s interior, the 1.5-kilometre wide AP7 does have an orbit that may, one day, intersect Earth’s.
However, right now, it’s at least two astronomical units (AU) away from our planet.
For context, one astronomical unit is just shy of 150 million kilometres, representing the distance between Earth and the Sun.
Today, AP7 is somewhere between Mars and Jupiter, and given its five-year orbit, spends most of its time out of our way. When it next intersects Earth’s path, we’ll be minding our own business on the opposite side of the Sun.
And fortunately, the astronomers who plucked this giant space rock out of the cosmos expect humans have ticked off just about every NEA there is left. Most have interior orbits like LJ4 and PH27.
One explanation as to why there are still undiscovered NEAs is the same reason why these three whoppers have eluded our telescopes until recently – sun glare.
Working at the Chilean Cerro Tololo Inter-American Observatory, the astronomers had just two 10-minute windows a night to study the area where these asteroids lurked, all while contending with light background skies due to the sun’s brightness.
“Only about 25 asteroids with orbits completely within Earth’s orbit have been discovered to date because of the difficulty of observing near the glare of the Sun,” says the study’s lead author Scott Sheppard.
“There are likely only a few NEAs with similar sizes left to find. These large undiscovered asteroids likely have orbits that keep them interior to the orbits of Earth and Venus most of the time.”
A timely reminder
Although we’re highly unlikely to encounter a planet destroying asteroid any time soon, space collisions do happen, and Earth is no exception, even if the most destructive impact occurred 66 million years ago and helped send the dinosaurs packing.
As part of research into planetary defence, NASA and the Applied Physics Laboratory at John Hopkins University recently crashed a spaceship into the nearby Dimorphos asteroid.
This experiment sought to understand whether such a ‘kinetic impact’ was able to transfer enough energy to alter the path of an asteroid. The results were better than anticipated.
Matthew Agius is a science writer for Cosmos Magazine.
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