Light, Dark Matter, and the Universe

Infrared light

Used to observe the center of the Milky Way, as it can penetrate dust clouds.

Dark matter

Composes about 85% of the Milky Way's mass, inferred through gravitational effects.

Big Bang

The hot and dense state in which the universe began.

Recombination

Process when charged particles combine to form neutral atoms, occurred 380,000 years after the Big Bang.

Cosmic Noon

Peak of star formation activity in galaxies, approximately 3 to 4 billion years after the Big Bang.

Cosmic Microwave Background (CMB)

Faint glow of radiation from the early universe, observable in the microwave part of the electromagnetic spectrum.

Local Group

Includes the Milky Way, Andromeda Galaxy, and smaller galaxies.

Virgo Supercluster

Larger cosmic structure containing the Local Group.

Hubble Time

Estimate of the age of the universe based on the Hubble constant, currently around 13.8 billion years.

Redshift

Galaxies moving away from each other, causing their light to shift toward longer wavelengths.

Hubble's Law

Linear relationship between recession velocity and distance of galaxies.

Expansion of the Universe

Rate described by the Hubble constant, currently accelerating possibly due to dark energy.

Protons

Positively charged particles found in atoms.

Electrons

Negatively charged particles found in atoms.

Neutral atoms

Atoms with an equal number of protons and electrons.

Gravitational effects

Inferences made based on the gravitational interactions between objects.

Expansion of the universe

Increase in the scale of space between galaxies over time.

Dark energy

Mysterious form of energy causing the accelerated expansion of the universe.

Hubble constant

Constant of proportionality in Hubble's Law, relating recession velocity and distance.

Microwave part of the electromagnetic spectrum

Range of electromagnetic waves with longer wavelengths than visible light.