I was taking pictures of the sky for about 30 minutes at night and it is about 35 degrees Fahrenheit. The pictures started to get really blurry and figured it might be because of the temperature. I brought it inside and there was condensation on the lens. I'm a beginner and I fear I really messed up but my instinct was to grab a lens cloth and wipe the lens, but that only created a smear. Then I detached the lens (looking at the internet, I'm now realizing I did pretty much everything wrong), just for a couple seconds because I wanted to see if there was condensation on the other side of the lens. I put it back on, turned off the camera and left it there. Do you think I might have let condensation occur on the sensor itself because of those few seconds where I detached the lens? I'm kind of worrying simply because I don't have a lot of experience with condensation and cameras. Will there be any permanent damage to the camera or lens?
Do you think I might have let condensation occur on the sensor itself because of those few seconds where I detached the lens?
There's a good possibility that opening the inside of the camera body allowed warm, moist air into the camera and caused more condensation than would otherwise have occurred. Some would have probably happened anyway.
Assuming the mirror was down and the shutter curtain was closed, the sensor stack probably did not have any direct contact with the air you let into the mirror box. After all, there's a light tight barrier between the mirror box and the sensor when the shutter is closed. Making sure the inside of the camera is completely dried out before operating the shutter should prevent any of the moisture from getting directly on the sensor.
The best thing to do now is put the camera and lens in a warm, dry, dust free place and let them dry out for a couple of days. Then put the battery back in the camera¹ and test it to see what you get. Testing for water spots on the front of the sensor stack is a lot like testing for dust spots. Cleaning the front of the sensor stack if it has water spots is also a lot like using any of the wet swab methods to clean dust off of sensor.
¹ Any time you suspect there is moisture in your camera, the first order of business should be to remove the battery until it is dried out.
The only way to know whether your camera has been damaged is to check it after the water has evaporated. It's likely your camera will continue to function normally, though with a slightly shorter life-span that it would have had otherwise. If you expect this to occur frequently, you should consider using weather resistant gear.
Condensation is pure water. If a surface is free of solutes, pure water will evaporate without leaving a mark. However, you'll need to clean off whatever you might have smeared onto the lens when you wiped it.