https://en.wikipedia.org/wiki/Nancy_Grace_Roman_Space_Telesc...
https://en.wikipedia.org/wiki/Extremely_Large_Telescope
Typically for non-adaptive optics telescope the atmosphere will limit you to the scale of about an arcsecond. Meaning objects which take up less than an arcsecond of the sky will appear as points. Adaptive optics telescopes however have much better resolving power.
https://en.m.wikipedia.org/wiki/Diffraction-limited_system
Practically to go really big you need to use interferometry. There are radio experiments that can do this at Earth scale - the Event Horizon Telescope can image very small objects (black holes) by making simultaneous observations from all over the world. The telescopes point at the same place and use very very good timestamping. At the South Pole we have a hydrogen maser for that. Then all the data gets sent somewhere for correlation and a lot of processing. The analogy I like most is imagining you have a big mirror (Earth) but you've blacked out almost the entire surface except a few points where the telescopes are.
Radio is particularly amenable to this because you can build big dishes more easily than for visible light, and the diffraction limit is lower because it's proportional to wavelength/aperture. So in addition to big dishes, you're observation wavelength is much much longer (mm vs nm).
There's a log-log plot on that wiki page which is quite difficult to read, but the important point is that radio is all the way at the top and the best we have is the VLBA.
Visible interferometry is much harder...!
Rubin is going to make a big difference in our knowledge of the asteroid belt, it will likely more than triple the size of our known catalog of asteroids. Its actually somewhat difficult to know exactly how much it will increase our knowledge. The bigger the telescope we build, the fainter the asteroids we see. The difficulty is that while we can make a pretty educated guess as to how many smaller ones there are, this is such a jump that the error bars on that guess is quite large. I am quite excited to see how the catalog of asteroids changes, I expect we will be finding a LOT of smaller rocks near the Earth.
Asteroids have a broad range of albedo, basically the brightness of the surface can vary from the blackest coal (like 3-5% of the light reflecting) to concrete (up to about 50%). All visible range telescopes will be susceptible to a bias in their observations, since a big black rock will be as bright as a smaller paler rock. We know that the asteroid belt favors the dark material.
In a couple of years, the Near Earth Object Surveyor (NEOS) space telescope will launch. NEOS is an IR telescope and will not have the same albedo bias. The trade off is that it will measure the black body radiation, meaning asteroids have to be nearer the sun. Broadly these are very complementary surveys, Rubin will be fantastic for filling out the main belt, and NEO Surveyor will do a great job on our neighborhood.
Source: I worked at Caltech on NEOS, I wrote the code they use to predict known asteroid orbits:
https://github.com/dahlend/kete
Edit: I failed to mention that Rubin is a big deal for a lot of time-domain astronomy, I'm just being selfish talking about asteroids only.
I loved astronomy as a kid and the town I grew up in has a "solar system way", basically a long street where a kind fellow (who in his freetime taught astronomy to nerds like myself and had built his own oberservatory in his backyard) had - with the blessing of the city - built a scale model of the solar system on a length of about 1.5 kilometers (a bit less than a mile).
I always found it fascinating when walking "through our solar system" with about 13 times the speed of light (normal walking translated into the distance at that scale) how veeeeeeeeeeery far apart things get in the solar system.
Sadly only in German: https://www.muenchberg.de/erleben/tourismus/tourismus-und-fr...
gnabgib•5h ago
taylorportman•5h ago
fastball•2h ago
minetest2048•1h ago
Interesting demo by Huygens Optics: https://youtu.be/qi8jmEbWsxU?si=rj0I3k-l74Xhg7vC