Astronomy

Question 1

Explain why the weight and value of g differ between the surface of earth and other celestial bodies

Answer 1

The bigger the mass of the planet the stronger the gravitational pull
w = mg -> more gravity causes an increase in weight

Question 2

What is the order of planets in the solar system in terms of distance from the sun

Answer 2

1- Mercury
2- Venus
3- Earth
4- Mars
5- Jupiter
6- Saturn
7- Neptune

Question 3

What is the geocentric model

Answer 3

that the Earth is the center of the universe, with the sun and planets revolving around it

Question 4

Why did people believe the geocentric model

Answer 4

Lack of technology: to the naked eye, it appeared that the Sun, Moon, planets, and stars all revolve around the Earth

Question 5

What is the heliocentric model

Answer 5

theory that places the SUN as the center of the universe, and the planets orbits around it

Question 6

What evidence is there for the heliocentric model

Answer 6

• Earth orbits the sun faster than mars, so we undertake it, so it appears to reverse its direction in the sky
• Galileo observing moons orbiting Jupiter showed not everything orbited the Earth

Question 7

Describe the planetary orbits

Answer 7

As the planets orbit the gravitational force causes the planet to change direction constantly so the speed is constant while the velocity is always changing
* The force causes the planet to accelerate without increasing its speed

Question 8

Explain how, for a stable orbit, the radius must change if
orbital speed changes

Answer 8

• If the planet moves closer to the sun -> its orbital radius decreases
• The gravitational attraction to the sun increases
• (Force increases, and so does acceleration, which causes an increase in velocity)
• So, the orbital speed of the planet increases

Question 9

What is steady state

Answer 9

says that the Universe has always existed, and that the Universe is expanding and constantly creating matter

Question 10

What is the big bang theory

Answer 10

• the Universe began from a very small region that was extremely hot and dense
• Then there was a giant explosion, which is known as the Big Bang
• This caused the universe to expand from a single point, cooling as it does so, to form the universe today

Question 11

What is evidence for the big bang theory

Answer 11

• Red shift
• Cosmic background radiation

Question 12

What is Cosmic background radiation

Answer 12

leftover radiation from the Big Bang or the time when the universe began

Question 13

What is red shift and how does it prove the universe is expanding

Answer 13

• Light appears red shifted from galaxies which are moving away from the earth
• The more red shifted the light from a galaxy is, the faster the galaxy is moving away from Earth

Question 14

What are the differences between Steady state and the Big bang theory

Answer 14

• The big bang theory believes that the universe always changes
• Steady state theory believes it is and always has been exact same

Question 15

How do all stars begin as

Answer 15

Nebulas

Question 16

How do stars SIMILAR size to the sun develop

Answer 16

1. red giant star
2. white dwarf
3. black dwarf

Question 17

How do stars of BIGGER mass to the sun develop

Answer 17

1. red super giant star
2. supernova
3. a neutron star, or a black hole (depending on size)

Question 18

Describe the evolution of stars though the nebula

Answer 18

A star forms from massive clouds of dust and gas in space, also known as a nebula which is pulled together by gravity

Question 19

Describe the evolution of stars though the star

Answer 19

The star is at this stable phase in its life

Question 20

Describe the evolution of stars though the red giant

Answer 20

When all the hydrogen has been used up in the fusion process, larger nuclei begin to form and the star may expand to become a red giant.

Question 21

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Answer 21

When all the nuclear reactions are over, a small star like the Sun may begin to contract under the pull of gravity. In this instance, the star becomes a white dwarf which fades and changes colour as it cools.

Question 22

how does the balance between thermal expansion and gravity affect the life cycle of stars

Answer 22

• pressure from hot gases pushed the star outwards,
• gravity pulls it inwards.
• if the pressure from the hot gases is stronger than the gravity, the star will expand.
• if it is weaker than the gravity, the star will contract.

Question 23

why are some telescopes located outside the Earth’s atmosphere

Answer 23

• telescopes in orbit around the Earth give much clearer images than ground-based telescopes (since clouds and dust in the air do not interfere with the image).
• also, the atmosphere absorbs some of the radiation they are designed to detect.

Question 24

How have methods of observing the universe changed over time

Answer 24

The invention of the telescope meant that much more detailed observations could be made, and it became possible to see objects much further away.