Distances: Crash Course Astronomy #25

What did ancient people believe the stars were?

• Gods in the sky

• Distant suns

• Holes in a huge crystal sphere

• Fireflies that got stuck in the black sky

Who calculated the circumference of the Earth over 2000 years ago?

• Aristotle

• Eratosthenes

• Ptolemy

• Galileo

What phenomenon did Eratosthenes use to calculate the Earth's circumference?

• The constellations

• The shadow of a stick at noon

• The Sun shining directly down a well at the summer solstice

• The phases of the Moon

What unit is used to measure the average distance from the Earth to the Sun?

• Astronomical Unit

• Kilometer

• Light year

• Parsec

What method is used to measure the distance to stars using the Earth's orbit?

• Doppler Effect

• Redshift

• Parallax

• Spectroscopy

Which star was the first to have its parallax successfully measured?

• Betelgeuse

• 61 Cygni

• Alpha Centauri

• Sirius

What is the distance light travels in a year called?

• Galactic mile

• Astronomical Unit

• Light year

• Parsec

How far away is Proxima Centauri, the nearest star to the sun?

• 100 light years

• 1000 light years

• 11.4 light years

• 4.2 light years

What is a parsec based on?

• The average distance from the Earth to the Sun

• The diameter of the Milky Way

• The angle a star shifts over the course of a year

• The distance light travels in a year

What did the ancient Greeks use to start measuring the universe?

• The distance to the nearest star

• The size of the Earth

• The distance to the Sun

• The size of the Moon