Short answer: Yes. Get some rocks into space, calculate the right trajectories so that their burn-up in the atmosphere occurs at the required point in the night sky (known physics calculation), calculate the timings of each so that they burn up at the right time (known physics calculation), and fire them off (known physics calculation).
A circle would involve firing multiple meteoroids at the same time towards the atmosphere at different angles, which would result in a sort of fireworks "burst" with all the meteoroids burning out in different directions.
The hardest part would be getting your launcher and your material into space, but we fire stuff into space with reasonable frequency, only difference with this one is that it's carrying a rock payload to fire back down.
Long answer: With enough time and material, you could effectively create a black and white television screen in the sky.
Step 1) Material
I need a lot of rocks. A Lot of rocks. Either I get it from Earth (costly, I have to fire everything up into space, and I have to dig it up from somewhere which would probably result in a very big hole or the suspicious lack of a mountain the next day), or a snag a handy passing asteroid (Theoretically not too difficult apart from the stopping it so that it doesn't kill us all part). Or you could mine it from the moon. All three are theoretically possible with enough money and time with our current technology.
Step 2) My TV
Simplified, an old CRT TV worked by firing electrons at a grid of pixels which would light up the specific pixel it hit. They would light up each require pixel in turn working from top left to bottom right, with the "refresh rate" of the screen being how quickly it could do all the pixels and return to the first.
Now, the theory still holds: I can create a "lit pixel" by fixing a meteoroid of the right size at the atmosphere, creating a single speck of light. In practice though, my refresh rate will probably be too slow (if I fire off the meteoroids at high enough rate they'd probably hit each other), so I'll modify the design a little.
Instead of a single launcher, I create a giant grid of launchers in space! One for each pixel, and they'll all fire off their meteoroids at the same time to create each frame on my Space TV tm. As each "frame" hits the atmosphere, it burns up and creates the image of that frame in the sky, by firing them all off consecutively, I can create a video of anything I like. Hell, if I wanted to, I could probably create a panorama that made it look like an Alien spaceship was coming in to land!
Step 3) The Details
Disregarding the insane amount of money, time and other considerations (that I'll get to), there are a couple of things you'd need to do:
- Get your launchers made — Each one won't be too hard: it's just a primitive meteor gun. It doesn't even need to fire them off that fast; gravity will do most of the work. The fun part will be how many you need. You need one for each pixel in your TV. According to This old CRT TV's had a resolution of about 750x500, which is 375000.
- So now you just need to make 375k launchable satellites and get them into Geosynchronous Orbit. Simples! Ok, not simple. Not even just "hard", it would be a monumental achievement. Up until now, Wikipedia estimates around 6,000 satellites have been launched. If you launched that many again, it would be enough for a square of about 77x77, which isn't bad I guess, but it would be clearly pixellated. Like I said, time and money. It may be possible to make a "carrier" which launches hundreds or thousands of your launchers into space: these things don't need to be big, they just need to be big enough that launching a 10cm piece of rock won't throw them out of their orbit.
- Lots and lots of identically sized rocks — In order to run a 10 second clip at say, 10hz (visible refresh rate but still pretty good), I need 100 identically sized rocks per pixel. So that's 37,500,000 rocks for my super-version, or 600,000 for my budget version. That's not actually too bad. There are 1000 10cm blocks in 1m3 of rock. 600m3 is a surprisingly small area: all you need is an area of rock 1m deep that is larger than 30mx20m. Loads of them in the world! The super version would be about 60 times that, which still isn't actually that much.
Once I've got everything in space, and connected together in the grip, the actual firing is pretty trivial. I can calculate the trajectories in advance, and then I'm just firing 10 10cm blocks of rock at the atmosphere every second, a rate that is will within achievable limits. I'll probably need to be firing some sort of rocket out the other side to maintain orbit, but it only needs to last for 10 seconds. As soon as that's happened I don't really care what happens, my light show is finished! Or I could be a little bit more careful, keep the mechanism up there and have scheduled viewing, maybe a bit of MarioKart.
There's one final problem though: Everything else in orbit. There is a massive amount of crap in orbit around the earth, so much so that people are starting to get worried about whether it will become impossible to launch anything soon without a catastrophic collision with existing debris. The major snag in this project would be anything that drifted between the launching platform and the earth during the firing period. That would totally mess up the effect.
Note: Obviously, a lot of this stuff is incredibly complicated and would probably never be pulled off due to the complications involved. It is, however, still possible, it would just require a massive amount of luck!