P1 - The Earth In The Universe

Question 1

What does the solar system consist of?

Answer 1

The solar system consists of a star (the sun), eight planets, the asteroid belt, other various things like to planets comments dust and asteroids

Question 2

What is the difference between planets and stars?

Answer 2

Stars are huge, very hot and very far away. They give out lots of light. Planets are smaller and they just reflect sunlight falling on them.The planets in the solar system are also much closer to us than any star - except the sun.

Question 3

How old is the solar system?

Answer 3

About 5000 million years old

Question 4

How did the solar system form?

Answer 4

It was filmed over a long period of time from big clouds of dust and gas.for some reason, one cloud started to get squeezed slightly. Once the particles had moved a bit closer to each other, gravity took overand pull things closer and closer until the whole cloud started to collapse in on itself.at the centre of this collapse, particles came together to form a protostar. When the temperature got high enough, a process called fusion started – hydrogen nuclei joined together to make helium.this process gives out lots of heat and light, and so the sun was born. All of the chemical elements in the cloud with her year items on helium and hydrogen also formed in the stars but the fusion of different nuclei. Around the sun, material from the cloud containing hydrogen, helium and heavier elements started to come together and these clumps became planets.

Question 5

How do we know that the solar system is at least 4500 million years old?

Answer 5

The oldest rocks on earth are actually meteorites, which were formed not long after the birth of the solar system. These are about 4500 million years old. Therefore we know that the solar system is at least that old.

Question 6

Where does the Sun and other star’s energy come from?

Answer 6

The fusion of hydrogen nuclei

Question 7

What are asteroids and comets?

Answer 7

Stuff left over from the formation of the solar system

Question 8

What are asteroids?

Answer 8

Rocks between Mars and Jupiter that didn’t form a planet, but stayed as smallish lumps of rubble and rock.

Question 9

What are comets?

Answer 9

Balls of rock, dust and ice which orbit the sun in very elongated eclipses, often in different planes from different planets. The sun is the end of the orbit.
As the comet approaches the sun, it’s ice melts, leaving a bright tail of gas and debris which can be millions of kilometres long.

Question 10

What Galaxy is our solar system in?

Answer 10

The Milky Way. The sun is about halfway along one of the spa alarms in the Milky Way. The distance between neighbouring stars in the galaxy is usually millions of times greater than the distance between planets in our solar system.

Question 11

What is the universe is made up of?

Answer 11

Thousands of millions of galaxies, which are millions of times further apart than the stars that are within a galaxy. Therefore the universe is mostly empty space and really really BIG.

Question 12

What is a light year and how fast does light travel?

Answer 12

A light year is the distance that light travels through a vacuum in one year. Light travels at 300,000 km/s. A light year is a measure of DISTANCE not time.

Question 13

Put these into size order, smallest first:

• the distance from the sun to the nearest star
• the diameter of earths orbit, the distance from the milky way to the nearest the Galaxy
• diameter of the earth
• diameter of the Milky Way
• diameter of the sun
• the diameter of the solar system.

Answer 13

• diameter of the earth
• diameter of the sun
• diameter of the earth’s orbit
• diameter of the solar system
• distance from the sun to the nearest star
• diameter of the Milky Way
• distance from the milky way to the nearest Galaxy

Question 14

How old is the earth?

Answer 14

5000 million years old

Question 15

How old is the sun?

Answer 15

5000 million years old

Question 16

How old is the universe?

Answer 16

14,000 million years old

Question 17

How can scientists use parallax to measure the distance of stars?

Answer 17

Astronomers take pictures of the sky six months apart (when the earth is at opposite sides of its orbit). The apparent movement of a star between the two photos lets you work out how far away it is. Stars further away appear to move less.

Question 18

You can also get an idea of the distance to a star by measuring its brightness. What do you have to take into account when doing this?

Answer 18

Stars that look bright could either be close to earth but not actually that bright, or a long way away from earth and very bright.

Question 19

What causes problems when trying to detect light and what did scientists do to overcome this?

Answer 19

Earths atmosphere because it absorbs quite a bit of light coming from space before it can reach us. Also light pollution (e.g. light thrown upwards from street lamps) makes it hard to see dim objects. To overcome this scientists put the Hubble space telescope in space, where you don’t get these problems.

Question 20

Why do we see stars and galaxies as they were in the past?

Answer 20

Electromagnetic radiation (including light) travels at about 300,000 km/s in a vacuum. Because things are so far away, it takes longer for the light to reach us. For example the sun is about 150 million km away from earth, we see the radiation from the sun about eight minutes after it actually left.

Question 21

How do we know that distant galaxies are moving away from us?

Answer 21

When a galaxy is moving away from us the wavelength of the light from it changes, it becomes redder. This is called red shift. The greater the red shift, the faster it is moving away from us. The more distant a galaxy, the faster it moves away from us. All this provides evidence that the whole universe is expanding.

Question 22

The Big Bang theory, how would it have started?

Answer 22

All the matter and energy in the universe must have been compressed into a very small space. Then it exploded and started expanding, and the expansion is still going on now.

Question 23

How is the age of the universe estimated?

Answer 23

By looking at the current rate of expansion. We think the big bang probably happened about 14,000 million years ago. However it is difficult to estimate as it is hard to tell how much the expansion has slowed down since the big bang.

Question 24

What does the universe’s fate depend on and why are these things hard to measure?

Answer 24

How fast it is expanding and the total mass there is in it. It is hard to measure how fast it is expanding because the universe is huge and it is difficult to accurately measure the large distances involved. It’s hard to measure the total mass in the universe because most of it appears to be invisible. Astronomers can only detect this dark matter by looking at the way it affects the movement of things we can see.

Question 25

Earth is an active planet, how will it change in the future?

Answer 25

Mountains will erode and new ones will form. The map of the world will be very different - whole continents will have moved.

Question 26

How is rock worn down, and how is new rock made?

Answer 26

Rocks are worn down by erosion. New rock is formed when lava from volcanoes sets.

Question 27

What evidence is there that rock is constantly forming?

Answer 27

Fossils provide this evidence. The animals and plants couldn’t have dug themselves into the middle of rocks – the rocks must have built up around them.

Question 28

How can the age of the Earth be estimated by looking at rocks?

Answer 28

By looking at the oldest rocks on earth, which are about 4000 million years old, we can tell that earth been around for at least that long.

Question 29

What happens during the rock cycle?

Answer 29

Particles are eroded from existing rock and get washed in to sea, they then settle as sediment. Over time, these sediments get crushed together to form sedimentary rocks. These can then get pushed to the surface and the cycle starts again. The sedimentary rocks can also descend into the heat and pressure inside the earth. If they descend, the structure of the rock can change completely as it gets heated and crushed.

Question 30

What observations lead to Wegener’s theory of the Continental drift?

Answer 30

Fossils of very similar plants and animals had been found on opposite sides of the Atlantic Ocean. Most people thought this was because the continent had been linked by land bridges, which had sunk and been covered by water as the earth cooled. As well as this people wondered why the coastlines of Africa and South America matched up so well and why fossils from sea creatures had been found high in the Alps.

Question 31

What was Wegener’s original hypothesis and what evidence did he find to back this up?

Answer 31

Africa and South America had previously been one continent which had then split. Evidence for this included matching layers in the rocks on different continents, and similar fossils in both South America and South Africa. His theory was that about 300 million years ago there had been one supercontinent – which he called Pangaea. According to Wegener, Pangaea broke into smaller chunks, and these chunks (our modern day continents) are still slowly drifting apart.

Question 32

Why wasn’t Wegener’s theory of the Continental drift accepted at first?

Answer 32

The main problem was that Wegener’s explanation of how the drifting happened wasn’t convincing, and the movement wasn’t detectable. Wegener claimed that the continent’s movement could be caused by tidal forces and the earth’s rotation – but other geologist showed that this was impossible. Also, it probably didn’t help that Wegener wasn’t a proper geologist – he was a meteorologist.

Question 33

What new evidence caused Wegener’s theory of the Continental drift to be accepted?

Answer 33

Scientists investigated the mid-Atlantic ridge, they found evidence that magma rises up through the sea floor and solidifies to form underwater mountains that are roughly symmetrical either side of the ridge. This suggested that the sea floor was spreading by a few cm per year. Even better evidence that the continents are moving apart came from the magnetic orientation of the rocks. As the liquid magma erupts out of the gap, iron particles in the rock tend to align themselves with earths magnetic field, and as it cools they set in position. Every half million years or so the earth’s magnetic field swaps direction – and the rock on either side of the ridge as bands of alternate magnetic polarity, symmetrical about the ridge. This was convincing evidence that the new sea floor was being created and continents were moving apart.

Question 34

What is earth’s core made out of?

Answer 34

Mainly iron and nickel

Question 35

What is the structure of the earth?

Answer 35

The earth is almost spherical and has a layered structure. There is a crust mantle and core.

Question 36

What is continental crust and oceanic crust?

Answer 36

Continental crust is what forms land, and oceanic crust is underneath oceans.

Question 37

Describe mantle

Answer 37

Mantilla has all the properties of a solid, except that it can flow very slowly. It flows in the convection currents.

Question 38

Why does mantle flow in convection currents?

Answer 38

Because of heat from the core and heat from radioactive decay in the mantle.

Question 39

What can tectonic plates cause?

Answer 39

Earthquakes, volcanoes – where plates meet magma is produced, which can rise up, forming volcanoes. When plates mountains are also formed when plates crash with each other. These processes also contribute to the rock cycle – pushing rock down, or up to Earth’s surface.

Question 40

What happens when there is an earthquake?

Answer 40

It produces wave motions (shock waves) which travel on the surface and inside the earth. We record these seismic waves all over the surface of the planet using seismographs.

Question 41

What do seismologists do?

Answer 41

Seismologists measure the time it takes for the shock waves to reach each seismograph. They also note which parts of the earth don’t receive the shock waves at all.

Question 42

What are the two different types of seismic waves that travel through earth?

Answer 42

P–waves and S–waves

Question 43

What is the difference between P-waves and S-waves?

Answer 43

P-waves travel through solids and liquids, S-waves only travel through solids. P-waves travel faster than S-waves. P-waves are longitudinal, S-waves are transverse.

Question 44

What happens when seismic waves reach a boundary between different layers of the earth?

Answer 44

Some waves will be reflected. The waves will also change speed as the properties (e.g. density) of the mantle and core change. This change in speed causes the waves to change direction – which is refraction. Most of the time the waves change speed gradually, resulting in a curved path. But when the properties change suddenly, the wave speed changes abruptly, and the path has a kink.

Question 45

What can a seismograph tell us about the layers of the earth?

Answer 45

The fact that P-waves change direction abruptly about halfway through the earth, indicates that there is a sudden change in properties – as you go from the mantle to the core. The fact that S-waves are not detected in the cores shadow tell us that the outer core is liquid – S-waves only pass through solids. S-waves do travel through the mantle, which shows that it’s solid.

Question 46

What do waves do?

Answer 46

All waves are basically just disturbances that are caused by a vibrating source. They carry and transfer energy in the direction that the wave travels, but do not transfer matter.

Question 47

What is frequency?

Answer 47

The number of complete waves passing a certain point per second OR the number of waves produced by a source each second.

Question 48

What is frequency measured in?

Answer 48

Hertz (Hz). 1Hz is one wave per second.

Question 49

What are transverse waves? Give examples of these

Answer 49

In transverse waves the vibrations are at 90° to the direction of travel of the wave. Most waves are transverse e.g. light and all other EM waves, waves on strings, S-waves.

Question 50

What are longitudinal waves? Give examples of these

Answer 50

In longitudinal waves the vibrations are along the same direction as the wave is travelling. Examples of longitudinal waves include sound and ultrasound and P-waves.

Question 51

What is the equation for wave speed?

Answer 51

Speed(m/s) = frequency(Hz) x wavelength(m)