Site Glossary

motion toward or away from an observer.

A telescope that detects radio waves from space using large dish antennas.

Electromagnetic waves with the longest wavelengths.

the unpredictable fluctuations or variations that occur when making measurements.

Horizontal displacement from launch to landing.

refers to the measurement of how something changes or progresses over time.

often expressed as a ratio of two different quantities, such as distance over time or change in a variable over time.

Time between detecting a situation and responding.

An evaluation of whether an answer’s sign, size, units and meaning are plausible.

a small, relatively cool type of star.

A large, expanded star formed after a Sun-like star exhausts the hydrogen in its core.