PLANETARY SECURITYAstronomers Are Getting Better at Detecting Asteroids Before They Hit Earth – and It Could Save Us from Catastrophe
Asteroid impacts have influenced every large body in the solar system. They shape their appearance, alter their chemical abundance and – in the case of our own planet at the very least – they helped kickstart the formation of life. But these same events can also disrupt ecosystems, wiping out life, as they did 66 million years ago when a 10km space rock contributed to the extinction of the dinosaurs (excluding birds).
On September 4 2024, astronomers discovered an asteroid, one meter in diameter, heading towards Earth. The space rock would burn up harmlessly in the atmosphere near the Philippines later that day, officials announced. Nevertheless, it produced a spectacular fireball that was shared in videos posted on social media.
The object, known as RW1, was only the ninth asteroid to be spotted before impact. But what of much bigger, more dangerous asteroids? Would our warning systems be able to detect all the asteroids that are capable of threatening us on the ground?
Asteroid impacts have influenced every large body in the solar system. They shape their appearance, alter their chemical abundance and – in the case of our own planet at the very least – they helped kickstart the formation of life. But these same events can also disrupt ecosystems, wiping out life, as they did 66 million years ago when a 10km space rock contributed to the extinction of the dinosaurs (excluding birds).
Asteroids are the material left over from the formation of our solar system, that was not incorporated into planets and moons. They come in all shapes and sizes. Their paths are determined by gravity and can, to some extent, be predicted. Of particular interest are the objects that are close to Earth’s orbit – called near-Earth objects (NEOs). As of Sep 2024, we know of approximately 36,000 such objects, ranging in size from several meters to a few kilometers.
But statistical models predict nearly 1 billion such objects should exist and we only know of very few of them.
We have been monitoring these asteroids since the 1980s and setting up more detailed surveys of them since the 1990s. The surveys use telescopes to make observations of the entire sky every night and then compare images of the same region on different dates.
Astronomers are interested in whether, in the same area of the sky, something has moved with respect to the stars from one night to another. Anything that has moved could be an asteroid. Observing its positions over a longer period allows team members to determine its exact path. This in turn enables them to predict where it will be in future, though such data collection and analysis is a time consuming process that requires patience.
