Newton's laws of motion 1. a body at rest remains at rest and a body in motion remains in uniform motion in a straight line unless acted upon by an external force
2. the acceleration of a body is directly proportional to the applied force and is in the direction of the straight line in which the force acts 3. for every force there is an equal and opposite force or reaction
Newton's law of universal gravitation - any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
matter - physical substance in general, as distinct from mind and spirit; (in physics) that which occupies space and possesses rest mass, especially as distinct from energy
planet - a celestial body moving in an elliptical orbit around a star
interstellar - occurring or situated between stars.
star - A huge ball of gas held together by gravity. The central core of a star is extremely hot and produces energy. Some of this energy is released as visible light, which makes the star glow. Stars come in different sizes, colors, and temperatures. Our Sun, the center of our solar system, is a yellow star of average temperature and size.
black hole
- a region of space having a gravitational field so intense that no matter or radiation can escape
cosmic microwave background - the thermal radiation left over from the time of recombination in Big Bang cosmology
electromagnetic spectrum - the range of wavelengths or frequencies over which electromagnetic radiation extends
energy - the ability to do work
galaxy - a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction
interstellar medium (ISM) - the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space
light year - a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles).
spectroscopy - the branch of science concerned with the investigation and measurement of spectra produced when matter interacts with or emits electromagnetic radiation.