Astronomy Lesson: Stars & Sun Review

Flashcards covering the definition of astronomy, distance measurements in space, travel times to celestial bodies, galaxy characteristics, and the origins of the universe.

What is the definition of Astronomy?

The scientific study of the Universe.

What two units do astronomers use to measure distance in space?

Light year and Astronomical unit.

When would an astronomer choose to use a Light Year over an Astronomical Unit?

They would use light years when distances get too big for the shorter astronomical units.

According to the travel table, how long would it take a Jet traveling at $600\,mi/hr$ to reach Mars?

$8$ years $10$ months.

How long would it take a Rocket traveling at $25,000\,mi/hr$ to reach Proxima Centauri, the nearest star outside our sun?

$114,155.2$ years.

How long does it take for a Sunbeam traveling at $186,300\,mi/sec$ to reach the Andromeda Galaxy?

$2.5$ million years.

What is the definition of a galaxy?

A collection of stars, dust, and gas bound together by gravity.

What are the three possible shapes of a galaxy?

Spiral, irregular, and elliptical.

How long ago do astronomers believe the universe began?

$13-15$ billion years ago (approximately $14$ billion years).

What specific evidence do astronomers use for the Big Bang Theory that involves a change in the frequency of a wave?

The Doppler Effect.

How long does it take sunlight (Sunbeam) to reach the Moon and the Sun?

It takes $1.2\,sec$ to reach the Moon and $8.5\,min$ to reach the Sun.

How long would it take a Jet traveling at $600\,mi/hr$ to reach the Moon?

$16.5$ days.

How long would it take a Rocket traveling at $25,000\,mi/hr$ to reach the Sun?

$4$ months.