Site Glossary

the magnitude of uncertainty associated with a measurement or calculation, independent of its sign or direction.

often represented by a positive value and is typically expressed in the same units as the measurement itself.

A spectrum containing dark lines where specific wavelengths have been absorbed by a cooler gas.

the rate at which an object changes its velocity over time.

(g) – Approximately 9.8 m/s² downward near Earth's surface.

A sensor used to measure acceleration.

hot material orbiting and falling toward a compact object.

technology that corrects astronomical images for distortions caused by Earth's atmosphere.

A drag force that opposes motion through air.

a method of representing or transmitting information using continuous, varying physical quantities.

How bright a star appears from Earth.