Exploring the Universe

Flashcards about the universe.

What are stars?

Huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores, held together by its own gravity.

What are solar systems?

A group of planets, meteors, or other objects that orbit a large star.

What are galaxies?

Sprawling systems of dust, gas, dark matter, and anywhere from a million to a trillion stars held together by gravity, often containing supermassive black holes at their centers.

What does our solar system include?

The Sun, eight planets, five officially named dwarf planets, hundreds of moons, and thousands of asteroids and comets.

What kind of galaxy is the Milky Way?

A barred spiral galaxy with two major arms and two minor arms.

Why is the light year used as an astronomical measurement of distance?

To have a more practical unit for measuring vast distances in space.

What is a fusion reaction?

A nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.

How does a fusion reaction produce energy in the core of a star?

Fusion reactions in the core convert hydrogen into helium, releasing a tremendous amount of energy in the process.