Earth & Motion
Universe & Beyond
Stars & Energy
Orbits & Shapes
Scientific Theories
100

The imaginary line Earth spins on.

What is the axis?

100

The theory that the universe began as a single point and has been expanding ever since.

What is the Big Bang Theory?

100

The process in which lightweight hydrogen nuclei combine into heavier helium nuclei.

What is fusion?

100

The shape of a planet’s orbit.


What is an ellipse?

100

This theory explains the origin and expansion of the universe.


What is the Big Bang Theory?


200

This is Earth’s circular movement around its axis.

What is rotation?

200

The path described by one celestial body in its revolution around another.

What is an orbit?

200

The type of nuclear reaction in which a massive nucleus splits into smaller nuclei, releasing energy.

What is fission?

200

The Sun is not at the center of Earth’s orbit but at one of these points.

What is a focus?

200

This theory states that stars and planets formed from a cloud of gas and dust.

What is the Nebular Theory?

300

This is Earth’s orbital movement around the Sun.

What is revolution?

300

This term describes an elongated circle or oval, such as a planet’s orbit.

What is an ellipse?

300

This process powers stars, including our Sun.

What is fusion?

300

The path a satellite takes around Earth.

What is an orbit?

300

his effect explains how sound or light waves change frequency when the source moves toward or away from an observer.

What is the Doppler Effect?

400

The reference point for latitude, located at 0°.

What is the equator?

400

The Sun, stars, and planets are all part of this vast system.

What is the universe?

400

his energy reaction is used in nuclear power plants, not in stars.

What is fission?

400

The imaginary line around which Earth rotates.

What is the axis?

400

When light from an object in space shifts toward shorter wavelengths, it appears this color.

What is a blue shift?

500

The point between two objects where they balance each other.

What is the barycenter?

500

The study of celestial objects beyond Earth’s atmosphere.

What is astronomy?

500

The balance between fusion pushing out and gravity pulling in defines this stage in a star’s life.

What is equilibrium?

500

This term describes a planet’s tilt, affecting seasons.

What is axial tilt?

500

The idea that planets move in elliptical orbits was proposed by this scientist.

Who was Kepler?