What tool is typically used to measure distances to celestial objects?

The tool that is typically used to measure distances to celestial objects is a radar or laser rangefinder. These instruments utilize the principles of radar or laser technology to send out waves or beams towards an object and measure the time it takes for the signal to return after reflecting off the object.

In astronomy, laser ranging can be particularly effective for measuring distances within our solar system. For instance, ranging missions can determine the distance to the Moon with great precision. Radar can also be utilized to measure the distances to various asteroids and planets by bouncing radio waves off their surfaces and calculating the distance based on the time taken for the signal to return.

In contrast, a barometer measures atmospheric pressure and is not related to celestial distances. An altimeter measures altitude above a specific reference point, typically used in aviation, and has no application in measuring distances to celestial bodies. While telescopes are essential for observing and studying these objects in detail, they do not measure distances directly but rather collect light from distant objects for analysis.