our place in universe

star

large, glowing ball of gas that generates heat and light through nuclear fusion

planet

moderately large object that orbits a star, shining by reflected light; can be rocky, icy, or gaseous

frost line

separates where water vs rocky planets can form

moon/satellite

an object orbiting a planet

asteroid

relatively small and rocky object that orbits a star, often non spherical

comet

relatively small and icy object orbiting a star, developing tails at certain distance

nebula

interstellar cloud of gas and/or dust emitting light from emission spectra, being heated up, etc.

galaxy

great island of stars in space, held together by gravity and orbiting a common centre, often black hole; ~10^9 stars

cluster

enormous cluster of galaxies, gas, and dark matter; ~ 10^14

universe

sum total of all matter and energy, including everything within and between all galaxies

composition of cosmos

65% dark energy, 30% dark matter, 4% free hydrogen and helium, 0.5% starts, 0.3% ghostly neutrinos, 0.03% heavy elements

astronomical unit

average distance between the Earth and the Sun / 8 light minutes

light year

distance that light can travel in a year

parsec

distance from the Sun to an astronomical object that has a parallax angle of one arcsecond; ~3.26 ly