Unit 1 Review: Vocabulary (Astronomy)

A set of vocabulary flashcards covering key astronomy terms from Unit 1 notes, including spectra, motion laws, and cosmic background concepts.

Spectral Lines

A dark or bright line in light, caused by atoms or molecules absorbing or giving off light at a specific color.

Red Shift / Blue Shift

A change in the color of light from a moving source. Red shift means it's moving away; Blue shift means it's moving closer.

Cosmic Background Radiation

Light leftover from the Big Bang, spread throughout the universe.

Big Bang Theory

The huge explosion that scientists believe started the universe.

Solar Nebula Hypothesis

The idea that the Sun and planets formed from a giant spinning cloud of gas and dust.

Rotation

An object spinning around its own center.

Revolution

When one object moves in a circle around another, like Earth going around the Sun.

Orbit

The path an object takes in space as it circles another object or point.

Ellipse

A flattened circle shape, like an oval.

Newton’s Law of Universal Gravitation

Every object in the universe pulls on every other object. The stronger the pull depends on how heavy they are and how close they are.

Newton’s First Law of Motion

An object will stay still or keep moving in a straight line at a steady speed unless something pushes or pulls it.

Newton’s Second Law of Motion

How much an object's movement changes depends on how strong the force pushing or pulling it is, and in what direction.

Newton’s Third Law of Motion

For every push or pull, there is an equal and opposite push or pull back.

Kepler’s First Law of Planetary Motion

Planets orbit the Sun in paths that are stretched circles (ellipses), with the Sun not quite in the middle.

Kepler’s Second Law

A line from a planet to the Sun sweeps out equal areas in the same amount of time, meaning planets speed up when closer to the Sun and slow down when farther away.

Kepler’s Third Law

The time it takes for a planet to orbit the Sun (its period) squared is directly related to how far it is from the Sun (its semimajor axis) cubed.

Electromagnetic Radiation

Energy that travels in waves, like light, radio waves, and X-rays, moving