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The Vera C. Rubin Observatory has been in testing mode for a while now, and will soon begin routine scientific operations, where it will scan huge chunks of the sky every night looking for transients: objects that change their brightness or positions in the sky. This includes exploding stars, flaring black holes… and a lot of much solar system objects in our cosmic back yard.

I’ve already written on how 2,000 asteroids were discovered in early observations. Well, scientists just announced that looking at early images taken over the course of about six weeks, they have now found a staggering 11,000 asteroids. Eleven thousand.

Those are new discoveries, previously unknown rocks mostly orbiting in the Main Belt between Mars and Jupiter. It also spotted an addition 80,000 previously known asteroids as well! Holy wow. Many of those are what are called recovered asteroids, ones that were not observed long enough initially to get good orbits for them, so they became lost. Rubin has found them again, adding a long time baseline of observations that help nail down the shapes of their orbits.

Here’s an animation of the discoveries, which come in bursts as observations were made. You can see the orbits of the inner planets and Jupiter, with asteroids in between as a blue fog. As Rubin looks in one part of the sky as seen from Earth, asteroids are discovered along that physical track, which appear as lighter blue dots (and their motions are continued as time goes on). You can get more info by reading the notes for the video on YouTube.

In that 11,000 space rock haul are 33 near-Earth objects, asteroids that get relatively close to Earth as we both orbit the sun. None of them gets close enough to be a threat however. I expect, though, that over time Rubin will find plenty of those (called Potentially Hazardous Objects), too.

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Incidentally, a paper has just been published where scientists ran simulations of how Rubin will see imminent impactors, (typically small) objects that are about to hit Earth [link to journal paper]. About a dozen of these have already been spotted (to be clear, I mean rocks that were found right before they hit our atmosphere, sometimes just hours in advance), almost all from the northern hemisphere. Rubin is in the Chile, so this will help us spot these smaller rocks. The scientists find that the observatory should catch one or two of these in the meter-size range per year, usually from about 1 – 3 days before impact. These rocks are small and therefore faint, which is why they typically aren’t seen until right before they burn up in our atmosphere. So this is good news too.

It also spotted 380 trans-Neptunian objects (TNOs), icy and rocky bodies that orbit the sun out past Neptune (you can think of Pluto as being the largest of these). Only about 5,000 TNOs are known, so in just a month and a half Rubin added about 8% more to that. After the sky survey is completed in about a decade, it should have found tens of thousands of these objects! That’s super important: the more we find, the more we can classify them by size and orbit. Our knowledge of this distant solar neighborhood is spotty, and Rubin will help us get a much better map of it. 

I’ll note that Planet 9, a still unconfirmed object potentially larger than Earth orbiting the sun very far out, was found due to its alleged influence on TNOs. Once we find lots more, that could help nail down its existence. It could even spot P9 directly! Time will tell.

Rubin hasn’t even really opened up for business yet and it’s already doing incredible work. I cannot wait until it’s up and running at full capacity. We’re going to learn so much about the changing sky.

You can keep track of Rubin’s asteroid discoveries on the Rubin Asteroid Discovery Dashboard. There’s also a cool interactive interface for exploring what it’s found (though it’s a CPU and RAM hog). It’s fun to poke around these.

• A Kuiper Belt Object called Altjira was thought to be a binary object, but new work indicates it’s likely actually a hierarchical trinary (with two objects orbiting each other and a third orbiting the two farther out); only one other such object is known, and these can help understand the dynamics of objects out past Neptune [link to journal paper].
  

• Many Kuiper Belt Objects are binary, and some are contact binaries (like Arrokoth, where the two components physically touch, making a snowman-like double-lobed body) — but models of formation have difficulty reproducing them. New work shows that a collapsing cloud of small pebbles can naturally create contact binaries of various lobe shapes and sizes [link to journal paper].

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