Our Place in the Universe Vocabulary

Flashcards covering key terms from the lecture notes on Our Place in the Universe.

Universe

Everything; the entirety of space and time.

Galaxy

A gravitationally-bound system that consists of stars, gas, dust, and dark matter.

Solar system

A gravitationally-bound system made up of a star (or two or possibly more) and all the planets, moons, comets, asteroids, dwarf planets, gas, and dust that orbit it.

Massive

Contains lots of stuff (matter), but not necessarily bigger in size (radius).

Light-year

The distance light travels in one year, used to measure vast distances in the Universe.

Cosmological principle

The assumption that the physical laws that apply here on Earth apply everywhere else in the Universe.

Hypothesis

An idea that can explain a phenomenon.

Theory

A hypothesis that tests have failed to disprove.

Physical law

A theory that has been very well tested and is of fundamental importance.

Occam’s razor

When faced with competing hypotheses that explain observations equally well, the one that requires the fewest assumptions should be used.

Scientific method

A systematic way of testing new ideas.