Space

Question 1

Name the planets in our solar system in order

Answer 1

Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune

Question 2

What is our galaxy called?

Answer 2

The Milky Way

Question 3

In general, as the distance from the Sun increases:

Answer 3

• the temperature decreases
• the time taken to orbit the Sun increases

Question 4

What are natural sateillites?

Answer 4

moons that orbit planets

Question 5

What is the heliocentric model?

Answer 5

the Sun is in the centre of the solar system and all of the planets and other objects in the system orbit the Sun

Question 6

Why do larger planets have rings?

Answer 6

• they have stronger gravitational field strength so attract debris

Question 7

What are bigger vs smaller planets made of?

Answer 7

bigger - mostly gas
smaller - mostly rock

Question 8

How is a planet formed?

Answer 8

For a planet to form, its own gravity must be strong enough to make it round or spherical in shape.

Question 9

What was the geocentric model?

Answer 9

The Earth was at the centre and planets moved around it.
Sun and moon orbited earth too.

Question 10

What did we think orbits were like in the past?

Answer 10

• we thought orbits were perfect circes with a fixed backdrop of starts

Question 11

What is an asteroid?

Answer 11

• made of metals and rocky material
• these orbit the Sun in highly elliptical orbits

Question 12

What is a comet?

Answer 12

• similar to asteroids, but are made of rocky material, dust and ice
• As a comet approaches the Sun, it begins to vaporise, which means that it turns into a gas. It then produces a distinctive tail

Question 13

What happens when a sateillite is moving too slowly and too fast?

Answer 13

slow - attraction is too strong and it falls towards Earth
fast - gravitational attraction is too weak and it moves away into space

Question 14

Evidence for heliocentrism

Answer 14

1) Mars’ retrograde motion. Earth rotates faster than Mars so we undertake it. Appears to reverse its direction in the sky.

2) Galileo observed moons orbiting Jupiter. Shows not everything orbits the Earth

3) Kepler observed planets orbit in ellipses (not circles)

Question 15

Explain how an orbit works.

Answer 15

• Gravitational force acts on a planet at a right angle to velocity of planet
• causes planet to accelerate towards the sun
• Planet speed doesnt change but it changes direction
• constant change of direction (as it is moving in a circle ish)
• means change in velocity (even if speed is constant)
• This is acceleration of the planet
• Means a force must be acting on it - gravitational force

Question 16

How does orbit change with distance from the sun?

Answer 16

• The gravitational attraction between two objects decreases with distance.
• This means that the closer the two objects are to each other, the stronger the force of gravity between them.
• If the force between them is greater, a greater acceleration will occur.
• The greater the acceleration, the greater the change in velocity - this causes the object to move faster.
• This means that objects in small orbits travel faster than objects in large orbits.

Question 17

What are the orbits that artifical sateillites have?

Answer 17

• polar orbits
• geostationary orbits

Question 18

What is a polar orbit and a geostationary orbit?

Answer 18

Polar - take the satellites over the Earth’s poles. Travel close to Earth at high speeds

Geostationary - higher and more slowly. Take 24 hours to orbit Earth.

Question 19

Life cycle of a star the same size as the sun/smaller

Answer 19

• Nebula (cloud of dust and gas)
• Gravity causes dust cloud to compress - become more hot and dense
• Forms protostar (high temp and pressure causing nuclear fusion)
• Nuclear fusion keeps the core of the star hot as it releases large amounts of energy
• Protostar becomes a main sequence star (outward pressure caused by fusion balances with outward pressure from mass)
• Forms a red giant (unstable and big)
• Ejects outer laters and becomes a white dwarf
• Cools into a black dwarf

Question 20

Life cycle of a star bigger than the sun

Answer 20

• Nebula (cloud of dust and gas)
• Gravity causes dust cloud to compress - become more hot and dense
• Forms protostar (high temp and pressure causing nuclear fusion)
• Nuclear fusion keeps the core of the star hot as it releases large amounts of energy
• Protostar becomes a main sequence star (outward pressure caused by fusion balances with outward pressure from mass)
• Forms a red supegiant (fusion occurs with heavier elements, creating elements geavier than iron - causes supergiant to become very big and collapse in on itself - supernova)
• Ejects outer laters
• Forms a neutron star or a black hole
• Forms black hole if it is extremely heavy

Question 21

What is a black hole?

Answer 21

Extremely dense point in space that has such a strong gravitational field that not even light can escape it.

Question 22

What is a main sequence star?

Answer 22

stable, with balanced forces keeping it the same size all the time
- gravitational attraction tends to collapse the star
- radiation pressure from the fusion reactions tends to expand the star
- forces caused by gravitational attraction and fusion energy are balanced

Question 23

What happens in a supernova?

Answer 23

During the majority of a star’s lifetime, hydrogen nuclei fuse together to form helium nuclei. As the star runs out of hydrogen, other fusion reactions take place forming the nuclei of other elements.

Elements that are heavier than hydrogen and helium are formed. Elements heavier than iron are formed in the supernova explosions of high mass stars

When the supernova explodes, all the elements produced are thrown out into the Universe

Question 24

What is red shift?

Answer 24

the increase in wavelength of light from objects that are moving away from you

observed wavelength is higher than waht it usually is

• light appears red shifted from galaxies moving away from Earth

v=fλ
if λ increases, f must decrease

Question 25

How does red shift provide evidence for the expanding universe?

Answer 25

• since further away galaxies are more red shifted, they must be moving at faster speeds away from Earth
• Galaxies are acelerating, so the universe must be expanding

Question 26

What is the big bang theory?

Answer 26

about 13.8 billion years ago the whole Universe was a very small, extremely hot and dense region. From this tiny point, the whole Universe expanded outwards to what exists today

Question 27

What is evidence supporting the big bang theory?

Answer 27

1) Red shift - further away galaxies are more red shifted. Further away=faster moving

2) CMBR (Cosmic Microwave Background Radiation) - the remains of the thermal energy from the Big Bang, spread thinly across the whole universe. About -270 °C

Question 28

What is dark energy?

Answer 28

• it is thought to cause the Universe to expand faster all the time
• astronomers have calculated that to make the Universe accelerate as observed, dark energy must account for 68 per cent of the Universe
• Provides an explanation for distant galaxies moving away increasingly faster

Responsible for the acceleration of the expansion of the universe

Question 29

What is dark matter?

Answer 29

• unknown material that explains why some galaxies rotate too quickly for the mass of their stars. (this would suggest that there is mass in the Universe that is invisible to the instruments used by scientists)
• Scientists only know it is there because it has gravity that affects objects nearby
• unknown substance providing the gravitational force that holds galaxies together