How do astronomers measure the distance between two celestial bodies?

Celestial distances are huge, so it really is amazing that we can measure the distance between Earth and another far-off celestial body.
One method of doing this is to use parallax. Parallax uses an apparent shift in motion when two different viewing angles are used. A simple illustration uses a moving car. Most people have gone on some kind of road trip before. When you look out the window, objects that are close to the car seem to zoom past the car quite quickly, but objects far from the car barely seem to move at all. We can measure the distances to objects with his concept. Stop the car, take a picture of a tree with a mountain in the background. Drive down the road a bit, and take another picture. This will cause the position of the tree to shift relative to the position of the mountain. The key is to then know how far you drove down the road. Knowing that information, you can use some fairly simple math to calculate the distance to the tree. For astronomy, replace the car with planet Earth and the tree with another star. Earth's first location would be location "A," and the second location would be where Earth is on our orbit 180 days later. Closer stars will appear to move more than more distant stars, and astronomers will work the same kind of math to calculate distances.
For stars that are much farther, we have to use Cepheid variable stars because we know they are a standard brightness. The farther away they are, the dimmer they will appear. The final method is to use the red shift caused by the Doppler effect.
https://www.space.com/30417-parallax.html