Units and Measurements in Space

These flashcards cover key vocabulary and concepts from the lecture on measuring distances in space and the structure of galaxies.

Kilometers (km)

A unit of measurement equal to 1,000 meters, often used to measure distances on Earth.

Astronomical Unit (AU)

A unit of distance equivalent to the average distance between the Earth and the Sun, about 149.6 million kilometers.

Light-year (ly)

The distance that light travels in one year, approximately 9.46 trillion kilometers.

Proxima Centauri

The closest star to the Sun, located about 4.2 light-years away.

Gravitational forces

The attractive forces exerted by objects with mass, responsible for keeping celestial bodies in orbit.

Black hole

A region in space with a gravitational pull so strong that nothing, including light, can escape from it.

Spiral galaxies

Galaxies characterized by spiral arms radiating from the center; the Milky Way is an example.

Elliptical galaxies

A type of galaxy that is oval in shape and lacks spiral arms, containing older stars.

Irregular galaxies

Galaxies that do not have a defined shape, often containing young stars and abundant gas and dust.

Milky Way galaxy

The galaxy that contains our solar system, characterized by a flat disk and spiral arms.

Quasar

A highly luminous and active galactic nucleus powered by a supermassive black hole, emitting massive amounts of energy.

Nebula

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

Supernova

A powerful explosion that occurs when a star exhausts its nuclear fuel and dies, often resulting in the creation of neutron stars or black holes.

Dark Matter

A mysterious form of matter that does not emit light or energy, making it invisible and detectable only through its gravitational effects.

Dark Energy

A form of energy that is thought to make up about 68% of the universe, driving its accelerated expansion.

Redshift

The phenomenon where light from an object is shifted toward the red end of the spectrum, indicating that the object is moving away from the observer.

Hubble's Law

The observation that the farther away a galaxy is, the faster it is moving away from us, supporting the Big Bang theory.

Cosmic Microwave Background (CMB)

The afterglow radiation from the Big Bang, now detectable as a faint microwave signal in every direction of the universe.

Solar System

The group of celestial bodies, including the Sun, planets, and their moons, that are bound by gravity.

Exoplanet

A planet that orbits a star outside of our solar system.