Section 5 - Astronomy

Question 1

Order of planets?

Answer 1

Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune

Question 2

Example of a dwarf planet ?

Answer 2

Pluto

Question 3

What are moons and how do they orbit earth ?

Answer 3

Moons are natural satellites and orbit earth in a circular orbit.

Question 4

What’s a satellite?

Answer 4

A satellite is an object that orbits a second massive object.

Question 5

What type of force is gravity?

Answer 5

Gravity is a centripetal force.

Question 6

How does a satellite stay in orbit?

Answer 6

A satellite stays in orbit because Gravity it pulls it down but because they’re moving sideways they constantly fall around the earth because it’s a sphere

Question 7

How is the moon accelerating and staying at the same speed at the same time ?

Answer 7

Because it’s changing direction and velocity takes into account direction

Question 8

What’s an asteroid?
Where are they usually found ?

Answer 8

Asteroids are lumps of rocks and metals that orbit the sun.
Asteroids are usually found in asteroid belts.

Question 9

What are comets?
What type of orbits do they have?

Answer 9

Comets are lumps of ice and dust that orbit the sun

They have highly eliptical orbits

Question 10

What’s the geocentric model?

Answer 10

The earth is in the centre of our solar system

Question 11

Why did the geocentric model become a thing?

Answer 11

Because people didn’t have telescopes and saw the moon and sun travelling across the sky every day.

Question 12

Who created the geocentric model?

Answer 12

The Greeks

Question 13

What was the heliocentric model?
What did it originally say?

Answer 13

Said the sun was at the centre of the solar system.
It originally said earth and all the planets orbited the sun in perfect circles

Question 14

How did galieo prove the geocentric model wrong?

Answer 14

Whilst looking at Jupiter he noticed there was stars near it.
When he looked back, they never moved away
This proves not EVERYTHING orbits the earth and could only be explained by it orbiting the sun

Question 15

What does the new heliocentric model change?

Answer 15

The planets orbits are eliptical not circular.
The planets orbit the sun

Question 16

What force creates orbits ?

Answer 16

Gravity

Question 17

Why is an object moving in a circular orbit constantly accelerating?
What force causes this?
In which direction does this force act?

Answer 17

-Because its velocity is changing.
-centripetal force
-towards the centre of a circle

Question 18

If the object wasn’t moving, what would the centripetal force cause it to do?

Answer 18

It would towards whatever it was orbiting

Question 19

What does gravitational field strength depend on?

Answer 19

Mass
Density

Question 20

Where would an object weigh more on, the earth or the moon?

Answer 20

The earth

Question 21

What happens to the gravitational field strength as you get closer to a planet?

Answer 21

It gets stronger

Question 22

What’s needed to balance a strong force when someothing orbits something in a circular motion?

Answer 22

A larger instantaneous velocity

Question 23

For an object in a stable orbit, if the speed changed what else must change?

Answer 23

The radius of its orbit must change if the speed its orbiting at changes

Question 24

How do stars initially form?

Answer 24

From a cloud of dust and gas called a nebula

Question 25

How’s a protostar formed?
What happens as the protostar gets denser?

Answer 25

Gravity pulls dust and gas together.
The temperature rises and hydrogen nuclei undergo nuclear fusion to form helium.

Question 26

How’s a main sequence star formed?
What happens to a stars time on main sequence the heavier it is?

Answer 26

-The outward pressure by thermal expansion balances the force of gravity pulling everything inwards.

• the heavier a star is the shorter its time on main sequence is.

Question 27

How’s a red giant or red supergiant formed?
Why does it turn red?

Answer 27

-The hydrogen in the core runs out, the core of the star is compressed till it’s dense and hot enough to expand the outer layers of the star.

• it turns red because it cools

Question 28

How’s a white dwarf formed after being a red giant?

Answer 28

Ejects it outer layers and leaves behind a hot, dense, solid core

Question 29

How’s a supernova formed after a red supergiant?

Answer 29

Big stars undergo more fusion. They expand and contract several times before exploding?

Question 30

What two things can form after a supernova?

Answer 30

A neutron star
A black hole

Question 31

How does a black hole form?

Answer 31

The exploding supernova throws it outer layers of dust and gas. This leaves behind a neutron star. If it’s big enough it will collapse into a black hole

Question 32

Describe how evidence has changed our ideas of the universe (heliocentric and geocentric models)

Answer 32

-Telescopes support the heliocentric model

-gelileos observations of the moons orbiting Jupiter

-meaning not everything orbits the sun

• satellite observations

-computer modeling

-heliocentric model verified by voyager missions