A massive, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter.

Galaxy

A giant cloud of dust and gas in space, often a region where new stars are born.

Nebula

A massive, luminous sphere of plasma held together by gravity.

A system of two stars that orbit around a common center of mass.

A group of stars that are gravitationally bound together.

An astronomical event that occurs during the last stages of a massive star's life, resulting in a spectacular explosion.

A region of space where the gravitational pull is so strong that nothing, not even light, can escape from it.

A small celestial body that orbits the Sun and has a visible coma (atmosphere) and tail when close to the Sun.

A small rocky body orbiting the Sun, mostly found in the asteroid belt between Mars and Jupiter.

A celestial body that orbits a star, has sufficient mass for its gravity to make it nearly spherical, and has cleared its orbit of other debris.

A natural satellite that orbits a planet.

A celestial body that orbits the Sun, is nearly spherical, but has not cleared its orbit of other debris.

A planet that orbits a star outside the Solar System.

An extremely luminous active galactic nucleus powered by a supermassive black hole.

A highly magnetized, rotating neutron star that emits beams of electromagnetic radiation.

A contracting mass of gas that represents an early stage in the formation of a star.

A substellar object that is not massive enough to sustain nuclear fusion of hydrogen in its core.

A small, dense remnant of a star that has exhausted its nuclear fuel and collapsed.

A dying star that has exhausted the hydrogen in its core and expanded in size.