Asteroid 2022 AE1 gave some astronomers a very stressful start to the new year. In the first week of 2022, initial data suggested that this 70-meter (230 foot) space rock was scorching towards Earth and set to make a catastrophic impact in just over 18 months' time. Was our planet crashing towards a very real Don't Look Up moment?
You'll no doubt be pleased to hear that it now looks highly unlikely that will be the case — Earth is safe from asteroids, for now. Nevertheless, it was enough of a scare to provide a very tense week at the European Space Agency (ESA).
The potential impact was first flagged up on January 6 by the Asteroid Orbit Determination, an automated system that calculates orbits from asteroid observation data provided by telescopes and observatories around the world. Over the course of the following week, other scientists from ESA tracked 2022 AE1 and reached the same conclusions. In fact, with each new observation, the risk of impact appeared to rise.
It was feared to be the riskiest asteroid seen in over a decade, scoring extremely high on the Palermo Scale, a system used by astronomers to rate the potential hazard of the impact of a near-Earth object.
"In my almost ten years at ESA I’ve never seen such a risky object," Marco Micheli, an astronomer at ESA’s Near-Earth Object Coordination Centre (NEOCC), said in a statement.
Their workings appeared to suggest that 2022 AE1 would collide with Earth on July 4, 2023 (Happy Independence Day, folks). It was too late to do anything about the potential impact, but the object was large enough to cause significant damage to the planet.
Then, the situation became even sketchier. On January 12, the asteroid could no longer be observed as it was temporarily outshone by the Moon. Astronomers were truly left in the dark, unable to gain any new insights about 2022 AE1 and its journey ahead. They simply had to let the Solar System do its thing and wait for the Moon to move.
One week later and astronomers were able to gather fresh observations. To their surprise — and relief — the new data showed the risk of an impact with Earth was slim to none. The risk of an asteroid collision with Earth was close to zero. Their latest estimates suggest that 2022 AE1 will safely fly by Earth in early July 2023 at a distance of about 10 million kilometers (6.2 million miles).
This may sound like a severe mistake to get something so serious so wrong. However, ESA explains that the observations of asteroids can often follow this pattern: the object first appears to be risky, the risk gets higher and higher, and then it will be revealed that the asteroid will fly nowhere near Earth.
The first observation is simply a single data point in the sky with no indication of its future direction, speed, backstory, or future journey. At least three observations are needed to get some idea of its orbit, but there is still huge uncertainty. At this point, it’s not possible to rule out that it will avoid Earth. As more observations come in, these uncertainties can be reduced, but the likelihood of a collision with Earth can remain the same. This gives the strong impression that the risk of an Earth collision is increasing. Eventually, a clear picture of the situation emerges. The potential hazard zone will become notably finer and more certain, making the risk to Earth suddenly drop.
Unless, of course, the asteroid really is heading towards Earth. Given the planet’s run of luck in recent years, let’s hope the astronomers at ESA and beyond continue to keep their eyes peeled and ready to act...