Exploring the Universe Flashcards

Flashcards for reviewing astronomy terms from lecture notes.

Star

An astronomical object that consists of a sphere of matter radiating heat and light, held together by gravity.

Solar System

A star and all natural objects that travel in orbit around it.

Galaxy

Groups of millions of stars held together by gravitational forces.

Nuclear Fusion Reaction

When small atoms join together to make a bigger atom, releasing energy in the process.

Orbit

A regular, repeating path that one object in space takes around another one.

Nebulae

Regions of intergalactic clouds of dust and gas in which stars are formed.

Protostar

A dense ball of gas that hasn’t developed into a star.

Red Giant

A small star that fuses helium, causing its outer layers to expand.

White Dwarf

The remains of the core of a small star after it has stopped fusion.

Red Supergiant

A large star that fuses helium, causing its outer layers to expand.

Supernova

An explosion of a red supergiant star.

Neutron Star/Pulsar

The remains of the core of a large star, made of densely packed neutrons.

Black Hole

An object that has gravity so strong that even light can’t escape it.

Absolute Magnitude (Brightness)

The total energy radiated by a star per second.

Apparent Magnitude (Brightness)

The brightness of a star when it is measured from Earth.

Big Bang model

The most accepted idea for how the universe began, stating that the universe started very hot and dense, then quickly expanded.

Accretion

Growing by collecting more matter using gravity.