Nuclear ___ is the energy source for all stars. It occurs in their core.
Hubble discovered that the universe is expanding by measuring the ___ of the light from distant galaxies.
sun-centered model, where everything orbits the sun
are used to analyze the spectrum of light from stars and planets
the distance light travels in a year
He showed that the planet's orbits are elliptical (not circular).
The sun will become a red giant when it runs out of ___.
Stars are “born” in clouds of gas and dust called ___.
The speed of ___is 300,000,000 meters per second.
Stars emit all of the ___ of the electromagnetic spectrum.
model of the universe that had everything orbiting Earth, in circular orbits
The farther away a galaxy is, the ___it is moving away from us.
brightest object in the night sky
The ___ part of Earth is its solid iron core.
The ___ radiation (microwave) is an imprint of the “Big Bang” on the entire universe.
The ___ of a star’s light can tell us its temperature, composition, whether it is moving towards us or away from us, and how fast it is rotating.
Main sequence stars, like the Sun, are fusing ___ into helium in their core.
The universe is almost 14 ___ years old.
The square of a planet’s orbital ___is equal to the cube of its average distance from the sun in AU.
Once it has run out of helium, it will stop all fusion, shed its outer layers, and become a ___ dwarf.