space physics

Question 1

state the order of the planets in the solar system

Answer 1

mercury
venus
earth
mars
jupiter
saturn
uranus
neptune

Question 2

categorise the planets into small rocky planets and large planets

Answer 2

• mercury venus earth and mars are small rocky planets

- jupiter saturn uranus and neptune are larger planets

Question 3

state the location of dwarf planets and give an example of a dwarf planet

Answer 3

dwarf planets can be found beyond orbit of neptune and an example is pluto

Question 4

describe what is meant by a moon

Answer 4

moons are natural satelites which orbit planets
most planets in the solar system have atleast one moon
some planets have a large number of moons

Question 5

describe what is meant by a galaxy

Answer 5

• a galaxy is a massive group of stars
  the milky way galaxy consists of hundreds of billions of stars and the universe consists of hundreds of billions of galaxies

Question 6

describe how a star is formed

Answer 6

stars are formed from clouds of dust and gas
scientists call this cloud of dust and gas a nebula
the gas inside a nebula is mainly hydrogen
in the first stage, gravity causes the cloud of dust and gas to collapse
as the dust particles move faster, the temperature rises to millions of degrees celsius.
scientists call collapsing cloud of hot gas and dust a protostar
if temperature of a protostar gets high enough, hydrogen nuclei join together to form helium this is known as nuclear fusion
protostar has now turned into a star (nuclear fusion is now releasing a huge amount of energy

Question 7

what is meant by a protostar

Answer 7

protostar- collapsing clouds of hot gas and dust

Question 8

describe the forces acting within a star

Answer 8

force of gravity acts inwards and tends to make star collapse
energy from nuclear fusion creates a force acting outwards, this tends to make the star expand

Question 9

why do scientists say that the forces acting within a star are at equillibrium

Answer 9

the force of gravity acting inwards, is balanced by the force of nuclear fusion acting outwards.

Question 10

describe the life cycle of stars that are the same size as the sun

Answer 10

-in the main sequence star, hydrogen nuclei join together to make laarger nuclei such as helium.
at some stage, the hydrogen in the star begins to run out
the outward force due to fusion energy is less than the inward force due to gravity
this causes star to collapse inwards
the collapse of the star causes temperature to rise
now helium nuclei fuse together to form heavier elements
star expands into a red giant at some point red giant stops fusing helium
star shrinks into a white dwarf
because white dwarf is no longer carrying out fusion it cools down
eventually stops releasing any energy and becomes a black dwarf

Question 11

describe life cycle of star larger than the sun

Answer 11

once these stars run out of hydrogen they expand into a red super giant.
once again helium nuclei fuse together to produce heavier elements
red supergiants stop carrying out fusion nucear fusion and explode
explosion is called supernova
temperature of supernova is high enough for elements heavier than iron to be produced
when supernova explodes, elements are distributed across universe
black hole gravity is so large that not even light can escape
neutron star- consists of densely packed neutrons.

Question 12

when can elements heavier than iron be produced

Answer 12

elements heavier than iron can only be produced in a supernova

Question 13

what do scientists call the earth orbiting the sun

Answer 13

a circular obit

Question 14

what holds the Earth in its orbit

Answer 14

-the force of gravity acting between the sun and the Earth holds the Earth in its orbit

Question 15

planets orbit the sun and what does the force of gravity do

Answer 15

planets orbit the sun and the force of gravity holds them in their orbit

Question 16

the moon is a natural satelite which orbits planets. what holds the moon in its orbit

Answer 16

the force of gravity holds the moon in its orbit

Question 17

what are artficial satelites

Answer 17

artificial satelites are man made

Question 18

what are geotstationary satelites

Answer 18

• artficial satelites that orbit once every 24 hours

- they always point to the same part of the Earth (other artifical satelites orbit more frequently)

Question 19

the force of gravity holds objects in their orbit. in the case of circular orbits the force of gravity leads to…..

Answer 19

-a changing velocity but not a change in speed

Question 20

velocity is the speed of an object in a given direction. as an object moves in its orbit its direction is constantly changing so this means its velocity is constantly changing as well. but what is constant

Answer 20

the speed is still constant, the force of gravity is changing the velocity but not the speed

Question 21

if the speed of a satelite increases what happens to the radius of the orbit

Answer 21

it decreases

Question 22

why does the radius of the orbit decrease when the speed increases

Answer 22

-because at a higher speed the satelite needs a greater force of gravity to stop it from flying off into space. so by moving closer to the earth, the gravitational force on the satelite is greater and so the satelite remains in stable orbit

Question 23

in the 1900s, astronomers were looking at the light emitted from different galazies
what did they detect

Answer 23

light from very distant galaxies had an increased wavelength compared to light from closer galaxies

Question 24

why are there dark lines in the spectrum

Answer 24

certain elements in the sun absorb light at specific wavelengths
those wavelengths appear as dark lines

Question 25

what do scientists call the red shift

Answer 25

light from distant galaxies has an increased wavelength, they have moved slightly towards the red end of the spectrum

Question 26

what does the red shift tell us

Answer 26

galaxies are moving away from each other
because the galaxies are moving away, the light waves are stretched
their observed wavelength has increased

Question 27

galaxies that are further away have a bigger….

Answer 27

red shift

so these galaxies are moving faster than ones that are closer

Question 28

nearby galaxies have a small red shift showing us that they are moving away
more distant galaxies have a larger red shift they are moving away….

Answer 28

faster

Question 29

what provides evidence that the universe is expanding

Answer 29

distant galaxies are moving faster than nearby galaxies.

Question 30

how do scientists believe the universe began ( big bang theory)

Answer 30

as a very small, hot dense region that expanded into the universe

Question 31

scientists had assumed that gravity would cause expansion to slow down. however observations of supernovae show that its expanding at an increasing rate
what have scientists suggested might be an explanation for this

Answer 31

the universe may contain matter and energy we cannot detect called dark matter and dark energy