Stars and Planets

Flashcards about Stars and Planets

What is a star?

A ball of gas held together by its own gravity.

What counteracts the force of gravity trying to collapse a star?

The pressure of hot gas and/or radiation in the star's interior.

How do stars begin?

Gas and dust in a nebula collapse under their own gravity to form a protostar.

What process occurs when a protostar becomes hot and dense enough?

Nuclear fusion occurs.

What is a Main Sequence Star?

A star that achieves stable Hydrogen fusion in its core.

How does a star's size affect its lifespan?

The larger the star, the faster it uses its fuel and the shorter its life.

What happens when a star's Hydrogen supply runs out?

It will start using Helium, causing it to expand into a red giant or super giant.

What happens to a star less than 8 solar masses when it runs out of fuel?

It will begin to shed excess mass in planetary nebulae.

What remains at the center of a Planetary Nebulae?

A White Dwarf star.

What happens to stars bigger than 8 solar masses?

Their outer layers collapse in while the core rapidly expands, forming a supernova explosion.

What is a Neutron Star?

A very small, very dense, and very hot star.

What happens if what's left after a Super Nova is LESS than 3 Solar Masses?

It will form a Neutron Star.

What happens if what’s left after a Super Nova is MORE than 3 Solar Masses?

A Black Hole forms.

What is Apparent Magnitude?

How bright a star appears to us on Earth, dependent on distance.

What is Absolute Magnitude?

The actual brightness of a star, independent of distance.

What is Parallax?

The apparent movement of objects at different distances due to movement of the observer.

What defines a Planet?

Orbits the sun, is round, and has cleared its orbit of debris.

What defines a Moon?

A celestial body that orbits a planet.

What are Nebulae?

Clouds of gas and dust located within galaxies.

What are Constellations?

A group of stars forming a pattern in the night sky.

What are Galaxies?

Systems of millions or billions of stars held together by gravity.

What is a Comet?

Object moving in space with a core of ice and dust.

What is a Meteor?

Matter from outer space burning up in Earth's atmosphere.

What is an Asteroid?

Small rocky body orbiting the sun.

What are Quasars?

Objects thought to be formed when black holes pull in stars and gas, releasing energy.