Cosmology key terms

Doppler shift

The change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source.

redshift

The increase in wavelength (and corresponding decrease in frequency) of light from an object moving away from the observer, indicating the object's recession.

redshift

The phenomenon where light from an object moving away from an observer is shifted to longer wavelengths, indicating the object's recession.

Doppler effect

The change in frequency or wavelength of waves in relation to an observer moving relative to the wave source.

redshift

The phenomenon where light from an object moving away from an observer is shifted to longer wavelengths, indicating the object's recession.

Doppler effect

The change in frequency or wavelength of waves in relation to an observer moving relative to the wave source, used to determine the motion of astronomical objects.

Doppler redshift

The increase in wavelength (or decrease in frequency) of light from an object moving away from the observer, indicating that the object is receding.

Gravitational redshift

The increase in wavelength of light escaping from a gravitational field, resulting from the effects of gravity on light as it moves away from a massive object.

Hubble's law

Hubble's law: an A-Level Physics term used in Hubble's law. It supports the objective to state and apply Hubble's law. by linking a measurement, observation or model to the correct astrophysics conclusion rather than using a generic space-science definition.

redshift

redshift: a specific A-Level Physics term for Hubble's law. Use it to support state and apply Hubble's law. by linking the named observation, graph, spectrum or measurement to the correct astrophysics conclusion. This definition is intentionally tied to Hubble's law, so it is not a generic astronomy label.

Hubble's Law

The law stating that the velocity of a galaxy is directly proportional to its distance from Earth, indicating the expansion of the Universe.

Redshift

The phenomenon where light from an object moving away from an observer is shifted to longer wavelengths, providing evidence for the expanding Universe.

Hubble's Law

Hubble's Law: an A-Level Physics term used in Hubble's law. It supports the objective to estimate the age of the Universe from Hubble constant values. by linking a measurement, observation or model to the correct astrophysics conclusion rather than using a generic space-science definition.

Hubble Constant

Hubble Constant: a specific A-Level Physics term for Hubble's law. Use it to support estimate the age of the Universe from Hubble constant values. by linking the named observation, graph, spectrum or measurement to the correct astrophysics conclusion. This definition is intentionally tied to Hubble's law, so it is not a generic astronomy label.

redshift

The phenomenon where light from an object moving away from an observer is shifted to longer wavelengths, indicating that the object is receding.

Hubble's law

A law stating that the recessional velocity of galaxies is directly proportional to their distance from Earth, supporting the theory of an expanding universe.

Quasar

A highly luminous object powered by a supermassive black hole at the center of a galaxy, emitting enormous amounts of energy, often observed at great distances.

Redshift

Redshift: an A-Level Physics term used in Quasars. It supports the objective to describe key observational features of quasars. by linking a measurement, observation or model to the correct astrophysics conclusion rather than using a generic space-science definition.

high redshift

A phenomenon observed in light from distant galaxies, indicating that they are moving away from us, which implies they are at a large distance due to the expansion of the Universe.

large distance

large distance: an A-Level Physics term used in Quasars. It supports the objective to explain why high redshift implies large distance. by linking a measurement, observation or model to the correct astrophysics conclusion rather than using a generic space-science definition.

quasar luminosity

The intrinsic brightness of a quasar, which is linked to the energy output from its active galactic nucleus.

active galactic nuclei

The central region of a galaxy that is extremely bright due to the presence of a supermassive black hole, often associated with quasars.

quasar

A highly luminous object powered by a supermassive black hole at the center of a galaxy, emitting vast amounts of energy.

redshift

The phenomenon where light from an object moving away from the observer is shifted to longer wavelengths, indicating the object's recession.

Transit Method

A technique used to detect exoplanets by observing the dimming of a star's light as a planet passes in front of it.

Light Curve

A graph that shows the brightness of a star over time, used to identify the presence of exoplanets through periodic dips in brightness.

Doppler shift

The change in frequency or wavelength of a wave observed when the source and observer are in relative motion.

Redshift

An increase in wavelength (or decrease in frequency) of light from an astronomical object, indicating it is moving away from the observer.

Transit depth

The fractional decrease in a star’s brightness when a planet passes in front of it, indicating the planet’s size relative to the star.

Transit duration

The time interval over which the star’s brightness is reduced during a planetary transit, providing information about the planet’s orbital speed and distance from the star.