How do astronomers find and track asteroids, and what will the Vera Rubin Observatory add?
Finding an asteroid means photographing the same sky again and again and spotting the dot that changed. A new Chilean telescope does it for the whole southern sky.
Guess first
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Which one is it?
Astronomers find asteroids by photographing the same areas of the sky again and again and looking for what has changed. Surveys such as Pan-STARRS in Hawaii detect differences from previous observations of the same areas, and in doing so discover new asteroids, comets, and supernovae. A dot that has changed is a candidate.
A single sighting is not enough to know where something is going. The , the official worldwide organisation for this, collects observations of asteroids and calculates their orbits, and it helps observers coordinate of possible near-Earth objects. More observations make an orbit more precise.
Step 1: photographs the sky
The same areas, again and again
Step 2: Software finds differences
A dot has changed since last time
Step 3: Report to the
Observations are collected there
Step 4:
More data sharpen the orbit
Several surveys share the work. Pan-STARRS's primary mission is now to detect near-Earth objects that threaten impact events, and the Catalina Sky near Tucson also searches for them. NASA's Planetary Defense Coordination Office, established in January 2016, looks for and catalogues near-Earth objects and helps prepare for a potential impact.
The newest tool is the Vera C. Rubin Observatory in Chile, named for the astronomer Vera Rubin, who pioneered discoveries about how galaxies rotate. It surveys the southern sky every few nights, building a ten-year time-lapse record. Its full began at the end of June 2026, and as of October 2026 it is expected to catalogue more than five million asteroids, about 100,000 of them near-Earth objects.
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Recap
Find it by spotting what changed between pictures, then track it with repeated observations until its orbit is known.
💡 A trick to remember it · Spot the difference, then spot it again: the first sighting finds an asteroid, the next ones tell you where it will be.
Surprising fact · Rubin's camera is the largest ever built, at 3.2 gigapixels, and the observatory is named for the astronomer who pioneered discoveries about galactic rotation.
Connects to
- 📈 What is the Torino scale, and why do asteroid impact odds rise and then fall?
- 🔭 What is a near-Earth object, and how many are there?
- 🏙️ What is the Bortle scale, and how much of the night sky have we lost to light pollution?
- ❄️ What lies beyond Neptune: the Kuiper belt and the Oort cloud?
- 🌌 How do we know something we can't see makes up most of the matter in the universe?
Sources (6)
No source, no claim. Every fact in this lesson (16 claims) cites at least one of these.