Astrophysics and Cosmology

energy transmitted by photons across the electromagnetic spectrum.

The complete range of electromagnetic radiation, arranged by wavelength or frequency.

an oval-shaped closed curve with two foci.

A rounded galaxy made mostly of older stars with little gas or dust.

A spectrum containing bright lines produced by excited atoms or ions.

the minimum initial speed required to escape a body's gravitational influence without further propulsion.

The boundary around a black hole beyond which escape is impossible.

a planet orbiting a star outside our Solar System.

The idea that the distances between most galaxies increase over time because space itself is expanding.

The increase in distance between most galaxies as space itself expands.