An infinite extension of three-dimensional space filled with matter which clumps together via gravity forming astronomical objects of various size such as galaxies, solar systems, stars, planets, and asteroids.
Matter
Our universe consists of hydrogen fused in the hearts of stars forming increasingly massive elements.
Atomic Elements
Individual atoms made of electrons, neutrons, and protons. The periodic table of elements lists all currently known atoms: pubchem.ncbi.nlm.nih.gov/periodic-table
Molecular Elements
Clumps of molecules made of two or more atoms of the same element bonded together.
Compounds
A substance made of two or more different elements combined in a fixed ratio.
Astronomical Objects
Naturally formed clumps of matter populating our universe including, but not limited to:
Definitions
- 1 solar mass = 1.989x10^30kg
- 1 Jupiter mass = 1.898x10^27kg
Galaxies
Vast systems consisting of stars, star clusters, planetary systems, interstellar gas and dust, and dark matter, all bound together by gravity; often featuring a central supermassive black hole.
Supermassive Black Holes
Extremely massive black holes typically found at the centers of galaxies >100,000 solar masses.
Black Holes
Objects whose gravity is so strong that nothing, not even light, can escape. The minimum size of a hydrogen fusing star is ~80 Jupiter masses, the Schwarzschild radius of a black hole born from this star would be ~2.26 kilometers.
Solar Systems
Objects typically made of one or more stars and/or black holes orbited by planets, dwarf planets, asteroids, and comets.
Stars
Objects whose mass are capable fusing hydrogen (>80 Jupiter masses.)
Brown Dwarf
Objects whose mass are incapable fusing hydrogen (>80 Jupiter masses,) but capable of fusing deuterium (<13 Jupiter Masses).
Gas Giant
Objects whose mass are incapable of fusing deuterium (<13 Jupiter masses) but greater than 10 Earth masses.
Planets
Objects whose mass are incapable of fusing deuterium (>13 Jupiter masses,) with sufficient self-gravity to pull themselves into a mostly spherical shape, and have cleared their neighboring region of planetesimals.
Dwarf Planets
Objects with insufficient mass for their self-gravity to form a mostly spherical shape (>400 kilometers,) hasn't cleared its neighboring region of planetesimals, and isn't the satellite of a planet.
Asteroids
Rocky/metallic objects whose radius is >1 meter with insufficient mass for their self-gravity to form a mostly spherical shape (<400 kilometers) and is not a comet.
Comets
Objects whose radius is >1 meter consisting mainly of ice, dust and gas smaller than (<400 kilometers) typically forming a coma and tail while close enough to a star.
Meteoroids
Objects whose radius is <1 meter.