The Rubin Observatory found 2,104 asteroids in just a few days. It could soon find millions more

It was weirdly emotional on Monday (June 23) as several grainy white specks streaked across my computer screen while ambient rhythms buzzed in the background. Those specks were part of a film that played during the Vera C. Rubin Observatory's highly anticipated first image release conference — and they each represented an asteroid that had just been discovered. It felt like witnessing something hugely profound, and there are two reasons why.

First of all, to put it simply, with just a few nights of data, the Rubin Observatory team was able to identify 2,104 never-before-seen asteroids in our solar system — seven of which are categorized as near-Earth objects. (No, none are expected to strike our planet. Don't worry). For context, there are approximately a million known asteroids in our cosmic neighborhood; over the next few years, Rubin could very well hike that figure up to five million.

"This is five times more than all the astronomers in the world discovered during the last 200 years since the discovery of the first asteroid," Željko Ivezić, Deputy Director of Rubin's Legacy Survey of Space and Time, said during the conference. "We can outdo two centuries of effort in just a couple of years."

This is astonishing in itself — talk about an exemplary first impression — but there's still that second thing that makes Rubin's new asteroid data incredible.

They can be formatted as movies.

Welcome to Hollywood, asteroids

For some context about Rubin, this observatory is our brilliant new ground-based eye on the universe, and is located at the El Peñón peak of Cerro Pachón in Chile. It has the ability to image giant swaths of the sky using the world's largest digital camera — and when I say giant, I mean giant.

One of its first presented images, for instance, features a bunch of glowing, hazy galaxies of all shapes and sizes. It's difficult not to daydream when looking at a couple of lovely lavender spirals that represent realms comparable to our entire Milky Way.

But what you see below in this image is only 2% of the full Rubin view:

The plan is for Rubin to capture such massive, high-resolution images of the southern sky once every three nights for at least the next 10 years. You can therefore consider it to be a super-fast, super-efficient and super-thorough cosmic imager. Indeed, those qualities are perfect for spotting some of the smallest details trailing through the space around our planet: asteroids.

"We make movies of the night sky to see two things: objects that move and objects that change brightness," Ivezić said. "Objects that move come in two flavors. Stars in our galaxy move, and they move slowly. Much faster objects are asteroids."

Zooming into a tiny portion of one of Rubin's images, Ivezić pointed out that there are actually invisible photobombers present. He was talking about the asteroid streaks Rubin's software so kindly removed from the main attraction (I mean, look at that spiral). However, the fact that those asteroids can be removed from an image means they can be precisely isolated to begin with, making it possible to really focus on them if you want to — something that isn't always possible with zippy, fleeting space objects.

In fact, it's tremendously difficult to record an asteroid at all.

"Asteroids, they disappear after you get one picture of them," Ivezić said, calling Rubin's ability to image small objects orbiting the sun "unprecedented."

In the Rubin image Ivezić called out to showcase the observatory's asteroid-tracking capabilities, the asteroid streaks are seen in different colors. This is because each corresponds to one exposure used to create the final image. You can think of it as different images stitched together to create a final view of the asteroids' trajectories. And to take things a step further, if you slap a few of these datasets together, you can indicate asteroid motion against the more static background of stars and galaxies — like a movie.

This feature of Rubin should be huge not only because it'd allow scientists to better study asteroid movements and discover new near-Earth objects, but also for humanity's efforts in planetary defense.

Another tool to protect Earth

Over the last couple of years, scientists have really started to question how we can protect our planet if an asteroid were headed our way.

NASA's wildly successful DART (Double Asteroid Redirection Test) mission — which sent a spacecraft on a death mission to crash into an asteroid and see if the object's trajectory can be changed — was arguably the feat that brought planetary defense to the public eye. It'd also be remiss not to mention all the recent anxiety surrounding Asteroid 2024 YR4, which was potent enough to even penetrate the jokes of a random comedy show in New York City I went to around the time it was making headlines. 2024 YR4 briefly had a head-turning likelihood of hitting our planet before that likelihood shot down to nil.

There was even a hearing about asteroid safety in May, held by the U.S. House Committee on Space, Science and Technology, during which U.S. Representatives expressed their concern that asteroid defense may be impacted by President Trump's major science funding cuts.

All of this is to say that I imagine a state-of-the-art asteroid detector is very welcome in the scientific community right now.

To really illustrate the ultimate promise of Rubin's asteroid adventures, Ivezić brought up a simulation of all asteroids expected to orbit our sun.

"This blue donut is a simulation of all asteroids we expect there," he said. "All of these new discoveries are found in this one narrow slice of this big donut. In two or three years, after we start LSST later this year, we will sweep around and discover all of the millions of asteroids."