2. Yr9 Astro Stuff (basic definitions)

Question 1

What is a universe?

Answer 1

Large collection of billions of galaxies

Question 2

What is a galaxy?

Answer 2

Large collection of billions of stars

Question 3

What galaxy is our solar system within?

Answer 3

Milky Way

Question 4

What are asteroids?

Answer 4

• small pieces of rocks which orbit the sun between mars and jupiter

Question 5

What are comets?

Answer 5

Rock / ice / methane / ammonia a few km in diameter

Orbit the sun in highly eccentric ellipses

Question 6

What do gravitational forces do?

Answer 6

• cause moons to orbit planets
• planets to orbit sun
• causes artificial satellites to orbit earth
• causes comets to orbit the sun
• gravitational force keeps them moving in curved paths (orbits)

Question 7

Why do comets travel faster when they are closer to the sun?

Answer 7

Gravitational forces are larger when the objects are closer
Farther away from sun - maximum GPE and lower KE

Closer to sun- lower GPE and maximum KE

Question 8

Describe the differences in the orbits of comets moons and planets?

Answer 8

• comets have highly elliptical orbits around the sun
• moons have circular orbits
• planets have slightly elliptical orbits

Question 9

What is the orbital speed equation?

Answer 9

Orbital speed = circumference (distance travelled) /orbital period (time to orbit once)

Orbital speed=
2πr (radius is distance from planet to sun) /T

Question 10

How to convert years to hours?

Answer 10

365 x 24 = 8760 hours