At 3 a.m. on a crisp May night in Chile, all seemed well with the world’s largest digital camera. Until it didn’t.
Inside the new Vera C. Rubin Observatory, Sandrine Thomas was running tests. As project scientist, her job is to keep the facility running. But suddenly, a line showing the telescope camera’s temperature changed. It had been flat. Now, it started to spike.
“That looks bad,” thought Thomas. And she was right.
Worried scientists quickly shut down the telescope.
I arrived a few hours later. I was jet-lagged but eager to get my first glimpse of the observatory. It sits on a high, flat-topped mountain called Cerro Pachón. From that perch, it aims a uniquely sharp eye on the cosmos.
With a wide and deep view of the sky, Rubin can see some of the slowest processes in the universe. The assembly of galaxies, for instance. Or the expansion of the cosmos. Rubin also maps the entire southern sky every couple of nights. That allows it to track some of the fastest events out there, such as stellar explosions.

Over the next 10 years, Rubin plans to take 2 million images. These will capture more of the cosmos than any other telescope. “For the first time in history, the number of cataloged celestial objects will exceed the number of living people!” astronomers wrote in 2019.
One of those astronomers was Željko Ivezić, at the University of Washington in Seattle. He’s been directing Rubin’s construction, which has taken decades.
The universe holds so many mysteries. “To answer them, you need something like Rubin,” Ivezić says. “There is no competition.”
But first, Thomas and her team had to get its camera back online.
From dark matter to asteroids
The idea to build Rubin came during another 3 a.m. vigil. This was in 1996. It happened on the next mountain over from Cerro Pachón.
Astronomer Tony Tyson and his colleagues had just brought a new camera to a telescope atop Cerro…
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