Earth, stars, galaxies and space

Question 1

what is the diameter of earth?

Answer 1

The diameter of the Earth is 12,800km (7,953 miles)

Question 2

how many times bigger is the sun than the earth?

Answer 2

the diameter of the Sun is 109 times that of the Earth’s

Question 3

how far is the earth from the sun?

Answer 3

The Earth is 150 million km (93 million miles) from the Sun

Question 4

how far away is the closest star?

Answer 4

The distance to the nearest star is four light years.

Question 5

What is the source of the Sun’s energy?

Answer 5

Nuclear fusion

Question 6

Which is a method of measuring the distance to stars?

Answer 6

Parallax

Question 7

How old is the Universe?

Answer 7

14000 million years old

Question 8

what was the main evidence for Wegener’s theory of continental drift?

Answer 8

Continents seem to fit together

Question 9

What causes seafloor spreading?

Answer 9

Movement in the solid mantle

Question 10

Where are volcanoes and earthquakes likely to happen?

Answer 10

At the edge of tectonic plates

Question 11

Which is evidence for seafloor spreading?

Answer 11

Magnetic stripes on the seafloor

Question 12

The vibrations detected from the site of an earthquake are called…

Answer 12

seismic waves

Question 13

What are the layers in the Earth, starting from the middle?

Answer 13

Core, mantle, crust

Question 14

What is the unit of wave frequency?

Answer 14

Hertz, Hz

Question 15

what is the formula for wave speed?

Answer 15

wave length (m) x frequency (Hz) = wave speed (m/s)

Question 16

Which type(s) of wave can be detected on the other side of the Earth from an earthquake

Answer 16

P waves

Question 17

what is a P wave?

Answer 17

I wave that travels like a worm and shakes the ground up and down

Question 18

what is an S wave

Answer 18

a wave that travels like a whip lash and shakes the ground side to side.

Question 19

which is more destructive towards buildings, P waves or S waves? and why?

Answer 19

S waves. because building are designed to withstand up and down motion, not side to side motion.

Question 20

The Earth is one of the………….planets orbiting the Sun, and there are many other members of the Solar System including …………, moons and ……….. Data provides the answers to many questions on this subject, but some questions remain unanswered.

Answer 20

The Earth is one of the eight planets orbiting the Sun, and there are many other members of the Solar System including asteroids, moons and planets. Data provides the answers to many questions on this subject, but some questions remain unanswered.

Question 21

The Universe is considered to be …………..there is, though most of it is thought to be ………..

Answer 21

The Universe is considered to be everything there is, though most of it is thought to be empty.

Question 22

Much is now known about the Earth and the place of the Earth in the Universe, for example:
the diameter of the Earth is 12,800km (7,953 miles)
the diameter of the Sun is …….. times that of the Earth’s
the Earth is …………………….. from the Sun
the distance to the nearest star is ……….. ………
years.

Answer 22

Much is now known about the Earth and the place of the Earth in the Universe, for example:
the diameter of the Earth is 12,800km (7,953 miles)
the diameter of the Sun is 109 times that of the Earth’s
the Earth is 150 million km (93 million miles) from the Sun
the distance to the nearest star is four light years.

Question 23

asteroids are much smaller than planets, and …….. the Sun. Most of the asteroids are between …………………….. and J……….r, but some come close to the Earth. Our Moon is nearly ………….. of the diameter of the Earth
………… have different ……..to those of planets, spending much of their orbital time far from the Sun. Comets are similar in size to asteroids, but are made of …. and …… The ……..when the comet approaches the Sun, and forms the …….. …………

Answer 23

asteroids are much smaller than planets, and orbit the Sun. Most of the asteroids are between the planets Mars and Jupiter, but some come close to the Earth
moons orbit planets. Most are tiny. Only a few are as large as our Moon, which is nearly a sixth of the diameter of the Earth
comets have different orbits to those of planets, spending much of their orbital time far from the Sun. Comets are similar in size to asteroids, but are made of dust and ice. The ice melts when the comet approaches the Sun, and forms the comet’s tail.

Question 24

Nearly all of the mass in our Solar System is in the ……..

Answer 24

Nearly all of the mass in our Solar System is in the Sun.

Question 25

In stars larger than our ….. helium ……….can be fused together to create larger ………. nuclei. As the Earth contains many of these larger ……….., like carbon, …………, ……., etc, scientists believe that our Solar System was made from the ……………. of an earlier ……..

Answer 25

In stars larger than our Sun helium nuclei can be fused together to create larger atomic nuclei. As the Earth contains many of these larger atoms, like carbon, oxygen, iron, etc, scientists believe that our Solar System was made from the remains of an earlier star.

Question 26

what can be fused together to create larger atomic nuclei.

Answer 26

In stars larger than our Sun helium nuclei can be fused together to create larger atomic nuclei.

Question 27

As the gas falls together, it gets ….. A star forms when it is … enough for a …… The Sun is very large. Its diameter is ….. times the Earth’s. The Sun is the source of nearly all the energy we receive. For many years, it was a mystery as to where this came from and this baffled the leading scientists. It is now understood that the……… …………….is the energy source. In ……………. ………….. smaller nuclei come together and form …………..nuclei. For example ………… ………..are joined together to make ………… ………… This releases enormous amounts of energy. . reaction to start. This releases ……. , and keeps the star …. The outward pressure from the ………… hot …………is balanced by the force of the star’s …………. This happened about …………years ago. This is quite recent in the history of the Universe, which is currently believed to be …………years old.

Answer 27

How stars and planets are formed:
As the gas falls together, it gets hot. A star forms when it is hot enough for a nuclear fusion reaction to start. This releases energy, and keeps the star hot. The outward pressure from the expanding hot gases is balanced by the force of the star’s gravity. This happened about 5 billion years ago. This is quite recent in the history of the Universe, which is currently believed to be 14 billion years old.

Question 28

The…………that distant stars and galaxies produce gives us information about the d………… to stars, and about how they are …………. In the future, this may allow us to find out if life exists on planets around some of these stars.

Answer 28

The radiation that distant stars and galaxies produce gives us information about the distances to stars, and about how they are changing. In the future, this may allow us to find out if life exists on planets around some of these stars.

Question 29

Powerful telescopes allowed astronomers to answer a question that had baffled scientists since the astronomer ………… (1473-1543) first suggested that the Earth moved …………. If the Earth moves, you would expect to see a different view of the stars at different times of the year, in the same way as the room you are in looks slightly different if you move your head to one side. That is to say everything seems to move in the opposite direction to your head, but the objects close to you seem to move more. This effect is called ………….

Answer 29

Powerful telescopes allowed astronomers to answer a question that had baffled scientists since the astronomer Copernicus (1473-1543) first suggested that the Earth moved around the Sun. If the Earth moves, you would expect to see a different view of the stars at different times of the year, in the same way as the room you are in looks slightly different if you move your head to one side. That is to say everything seems to move in the opposite direction to your head, but the objects close to you seem to move more. This effect is called parallax.

Question 30

So if the Earth was moving, why did the stars always look the same?

Answer 30

The answer to the question was revealed by more powerful telescopes. These showed that nearby stars do seem to move from side to side and back every year when compared with very distant stars, but that the amount of movement is tiny.

Question 31

Telescopes in space, such as the ………………Space Telescope, can observe the whole sky. They are above light pollution and above dust and clouds in the atmosphere. What are the disadvantages? .

Answer 31

However, they are difficult and expensive to launch and maintain. If anything goes wrong, only astronauts can fix them.

Question 32

What is a light-year ?

Answer 32

A light-year is the distance light travels in a year. Light travels very fast (300,000 km/186,282 miles per second), and takes only about eight minutes to reach us from the Sun. It takes over four years to reach us from the next nearest star (Proxima Centauri), and 100,000 years to cross the Milky Way galaxy. We say that the distance to the next nearest star is four lightyears, and the diameter of the Milky Way is 100,000 light years.

Question 33

When initial distances to stars were being established more than one method was employed. After establishing distances of nearby stars using the parallax method, what other method was used?

Answer 33

After establishing distances of nearby stars using the parallax method, the ‘brightness method’ was used to approximate distances to further stars. Other methods were also used.

Question 34

What is the assumptions with the parallax method ?

Answer 34

with the parallax method an assumption made is that during the total time in which the measurement is taking place, distance remains constant between the two stars.

Question 35

What explanations can be developed to illustrate the theory that the dinosaurs were destroyed by an asteroid impact?

Answer 35

asteroids are small objects orbiting the Sun
some asteroids have orbits close to the Earth
the dinosaurs died out at about the same time as a large crater was made in Mexico.

Data statements tell you facts, and may contain measurements.

Explanations seek to explain the data, and formulating an explanation requires imagination and creativity. One explanation is that an asteroid collision may have killed off the dinosaurs. The asteroid impact would have created dust that blocked out light and heat from the Sun.

Question 36

A good explanation will explain data, and link together things thatwere not thought to be related. What else should it make ? Use this in relation to the extinction theory of dinasours
asteroids often contain the rare metal iridium - data
a huge asteroid impact would send iridium dust throughout the world - prediction
sedimentary rocks from the time the dinosaurs died out contain iridium - data
when the asteroid crashed, the iridium came from the dust tha tblocked out the Sun - explanation.

Answer 36

Predictions

A good explanation will explain data, and link together things thatwere not thought to be related. It should also make predictions.
asteroids often contain the rare metal iridium - data
a huge asteroid impact would send iridium dust throughout the world - prediction
sedimentary rocks from the time the dinosaurs died out contain iridium - data
when the asteroid crashed, the iridium came from the dust tha tblocked out the Sun - explanation.

Question 37

The asteroid theory is not the only one about the death of the dinosaurs. Others are what?

Answer 37

The asteroid theory is not the only one about the death of the dinosaurs. Other are:
there were huge volcanic eruptions in India at the time the dinosaurs died out - data
big volcanic eruptions cause dust clouds thatblock out the Sun - data
the big Indian eruptions could have killed out the dinosaurs by cooling the Earth - explanation

Question 38

Not all scientific questions have answers at this time. For some of the questions there is not enough data yet. What is an example of this question? And give an example of a questions, where there may never be the data you need?

Answer 38

is there life on distant planets? For other questions, there may never be the data you need. An example of this is: what happened before the ‘Big Bang’ when the Universe was created?

Question 39

List 4 things you know about Galaxies?

Answer 39

1) Galaxies contain thousands of millions of stars.
2) For many years, it was thought that our galaxy, which is the Milky Way, was the only one that existed, and that the blurry nebulae that could be seen were clouds of dust and gas in the Milky Way.
3) Observations of many of these nebulae by astronomers such as Edwin Hubble showed they were in fact galaxies outside the Milky Way
4) and that distant galaxies are all moving away from us.

Question 40

Whose observations led to the ‘Big Bang’ explanation of the beginning of the Universe? What date did it set this at ?

Answer 40

Hubble’s observations led to the ‘Big Bang’ explanation of the beginning of the Universe, and set a date for this at 14,000 million years ago.

Question 41

What is believed to be the future of the Universe ?

Answer 41

the Universe will continue to expand in the way it is at the moment. Perhaps gravity will eventually win and pull all the fleeing galaxies back together again. Better observations of very distant galaxies and a better understanding of the mysterious ‘dark matter’ are needed before these will be understood.

Question 42

The astronomer Edwin Hubble (1889-1953) did what? What did he find?

Answer 42

The astronomer Edwin Hubble (1889-1953) measured the distance to many galaxies, and also the speeds with which they are moving away from us. He found a strong correlation between these factors.

Question 43

What correlation is summed up in Hubble’s Law?

Answer 43

This correlation is summed up in Hubble’s Law which says that the speed at which a galaxy moves away from us is proportional to its distance from us.

The causal link which explains this law is that space itself is expanding.

As the Universe expands, galaxies that are already further apart will increase in separation even more, and so move away at higher speeds

Question 44

What is red-shift?

Answer 44

The development of powerful telescopes allowed astronomers to see distant galaxies. The light observed was shifted towards the red end of the spectrum. This phenomenon is known as red-shift. The degree to which light has been shifted indicates how fast the galaxies are moving away

Question 45

what are P-waves (P stands for primary)?

Answer 45

P-waves (P stands for primary) arrive at the detector first. They are longitudinal waves which mean the vibrations are along the same direction as the direction of travel.

Question 46

Other examples of longitudinal waves are?

Answer 46

Other examples of longitudinal waves include sound waves and waves in a stretched spring.

Question 47

What is Amplitude?

Answer 47

As waves travel, they set up patterns of disturbance. The amplitude of a wave is its maximum disturbance from its undisturbed position. Take care: the amplitude is not the distance between the top and bottom of a wave. It is the distance from the middle to the top.

Question 48

What is a Wavelength?

Answer 48

The wavelength of a wave is the distance between a point on one wave and the same point on the next wave. It is often easiest to measure this from the crest of one wave to the crest of the next wave, but it doesn’t matter where as long as it is the same point in each wave

Question 49

What is the frequency of a wave ?

Answer 49

The frequency of a wave is the number of waves produced by a source each second. It is also the number of waves that pass a certain point each second. The unit of frequency is the hertz (Hz). It is common for kilohertz (kHz), megahertz (MHz) and gigahertz (GHz) to be used when waves have very high frequencies. For example, most people cannot hear a high-pitched sound above 20kHz, radio stations broadcast radio waves with frequencies of about 100MHz, while most wireless computer networks operate at 2.4GHz.

Question 50

The distance travelled by a wave is calculated using this what equation?

Answer 50

The distance travelled by a wave is calculated using this equation:

Distance = speed x time

Question 51

What is the equation for wave speed?

Answer 51

wave speed = frequency x wavelength

wave speed = frequency x wavelength

For example, a wave with a frequency of 100Hz and a wavelength of 2m travels at 100 x 2 = 200m/s.

The speed of a wave does not usually depend on its frequency or its amplitude.

Question 52

How old is the Earth? When is there evidence that living things existed on Earth ?

Answer 52

the Earth is about 4,500 million years old
there is evidence that living things existed on Earth at least 3,500 million years ago
no one was there to record how life began

Question 53

What is the main theory about how life on earth began?

Answer 53

Through the study of simple organisms and the chemistry of living things, we can develop scientific theories about how life on Earth began. The main theory is that living things developed from molecules that could replicate, or copy, themselves, rather like DNA does.

There are two possible origins for these replicating molecules:
they were produced by the conditions on Earth at the time
they came from somewhere else, such as another planet in our Solar System, or further out in space.

Over many millions of years these molecules joined with other molecules, becoming gradually more complex and dependent on each other. The process of evolution by natural selection eventually led to all of the different living things that we see on Earth today.

Question 54

How did molecules become more complex ?

Answer 54

Over many millions of years these molecules joined with other molecules, becoming gradually more complex and dependent on each other. The process of evolution by natural selection eventually led to all of the different living things that we see on Earth today.

Question 55

Who was Charles Darwin?

Answer 55

Charles Darwin was an English naturalist who studied variation in plants and animals during a five-year voyage around the world in the 19th century. He explained his ideas on evolution in a book called, ‘On the Origin of Species’, published in 1859.

Question 56

What is the basic idea behind the theory of evolution?

Answer 56

The basic idea behind the theory of evolution is that all the different species have evolved from simple life forms. These simple life forms first developed more than 3 billion years ago (the Earth is about 4.5 billion years old). The timeline below shows some of the key events in the evolution of life on Earth, from the first bacteria to the first modern humans.

Question 57

What is Natural selection?

Answer 57

The theory of evolution states that evolution happens by natural selection. The key points are that:
individuals in a species show a wide range of variation
this variation is because of differences in their genes
individuals with characteristics most suited to the environment are more likely to survive and reproduce
the genes that allow these individuals to be successful are passed to their offspring.

Question 58

What can variation be caused by?

Answer 58

You need to remember that variation can be caused by both genes and the environment. But it is only variation caused by genes that can be passed on to the next generation.

Question 59

In Darwin’s theory, what sort of variation can be passed on to the next generation.?

Answer 59

You need to remember that variation can be caused by both genes and the environment. But it is only variation caused by genes that can be passed on to the next generation.

Question 60

What have Farmers used selective breeding for?

Answer 60

Farmers have used selective breeding for centuries to increase milk yield in cattle, produce larger eggs from chickens and obtain more grain from wheat.

Question 61

What are Mutations ?

Answer 61

Mutations are changes that can occur in genes. These changes are random and can be caused by background radiation and chemicals that we come into contact with, for example the chemicals in cigarette smoke.

Question 62

What happens with a mutuation?

Answer 62

Sometimes these changes can be so severe that the cell dies, sometimes the cell can divide uncontrollably and become cancerous, and sometimes the changes are small and the cell survives. Very rarely the changes may even be beneficial to us and produce new and useful characteristics.

Question 63

When are mutations passed on ?

Answer 63

Passing on mutations

If these changes occur in normal body cells, the changes are lost when we die. But if the changes occur in our sex cells such as sperm and ova, there is the possibility that the changes in the gene will be passed onto the next generation.

It is when these changes are passed on to the next generation that natural selection can either ensure that they are selected if they are useful, or disappear from the gene pool if they are not

Question 64

What causes a new species to be created?

Answer 64

The combined effect of these mutations, environmental changes, and natural selection, can sometimes produce changes in the organism that are so great that a new species is produced. This does not happen very often and only occurs when the mutated organism can no longer breed with the original species and is capable of producing fertile offspring

Question 65

Darwin was not the only person to develop a theory of evolution. Who else did ?

Answer 65

Jean-Baptiste Lamarck was a French scientist who developed an alternative theory at the beginning of the 19th century. His theory involved two ideas. These are:
the law of use and disuse
the law of inheritance of acquired characteristics.

Question 66

Lamarck’s theory cannot account for all the observations made about life on Earth.what couldn’t it account for?

Answer 66

Lamarck’s theory cannot account for all the observations made about life on Earth. For instance, his theory would predict that all organisms gradually become complex, and simple organisms disappear.

Darwin’s theory can account for the continued presence of simple organisms.

Question 67

what is the story of the Peppered moths?

Answer 67

Before the Industrial Revolution in Britain, most peppered moths were of the pale variety. They were camouflaged against the pale birch trees they rested on. Moths with a mutant black colouring were spotted easily by birds and eaten. This gave the white variety an advantage, making them more likely to survive and reproduce.

Airborne pollution in industrial areas blackened the birch tree bark with soot. This meant the mutant black moths were now camouflaged, while the white variety became more vulnerable to predators. It gave the black variety an advantage. They were then more likely to survive and reproduce. Over time, the black peppered moths became far more numerous in urban areas than the pale variety.

Question 68

How does DNA support the theory of evolution?

Answer 68

Scientists can now examine the DNA from different species of organism and use the data produced to see how closely related the two species are to each other. By collecting a lot of this data, scientists can compare the results with conventional ideas about how organisms have evolved. What they found was that DNA data supported the conventional theory of evolution.

Question 69

what did Darwin notice on the Galapagos ?

Answer 69

Darwin noticed that different islands in the Galapagos had different types of finches adapted to eating the type of food found on each island. It was only when Darwin produced his theory of evolution by natural selection that these two unrelated facts were linked together.

Question 70

The Sun is very large. Its diameter is ….. times the Earth’s. The Sun is the source of nearly all the energy we receive.

Answer 70

The Sun is very large. Its diameter is 109 times the Earth’s.

Question 71

What is the energy source of the sun? How does it create energy?

Answer 71

It is now understood that the nuclear fusion is the energy source. In nuclear fusion, smaller nuclei come together and form larger nuclei. For example hydrogen nuclei are joined together to make helium nuclei. This releases enormous amounts of energy.

Question 72

Why is a certain level of uncertainty found in the results?

Answer 72

As methods were reliant on each other, a certain level of uncertainty is found in the results.

Question 73

What is understood about the beginning and end of the Universe?

Answer 73

There are many questions left unanswered about the beginning and end of the Universe. Observations suggest it contains a lot of ‘dark matter’ that cannot be seen, and this is not yet clearly understood.

Question 74

What was early Earth like?

Answer 74

early Earth was hotter and the atmosphere consisted mostly of carbon dioxide (with other gases such as ammonia and methane).

Question 75

Everything we know about stars and galaxies has come from what>

Answer 75

Everything we know about stars and galaxies has come from the light, and other radiations, that they give out. This has become more difficult to see from the Earth’s surface, as light pollution from towns and cities interferes with observations of the night sky.

Question 76

What are nebulae ?

Answer 76

Looking at the sky with the naked eye shows the Sun, Moon, stars, planets and a few cloudy patches called nebulae. When telescopes were invented and developed, astronomers could see that some of the nebulae were in fact groups of millions of stars. These are galaxies.

Question 77

The Earth is just one of how many planets orbiting the Sun, which is a ? . The orbits all lie in the same plane, and the planets all go round in the same direction.

There are many other members of our Solar System:
asteroids are much smaller than planets, and orbit the Sun. Most of the asteroids are between the planets Mars and Jupiter, but some come close to the Earth
moons orbit planets. Most are tiny. Only a few are as large as our Moon, which is nearly a sixth of the diameter of the Earth
comets have different orbits to those of planets, spending much of their orbital time far from the Sun. Comets are similar in size to asteroids, but are made of dust and ice. The ice melts when the comet approaches the Sun, and forms the comet’s tail.

Answer 77

The Earth is just one of the eight planets orbiting the Sun, which is a star.

Question 78

Do the orbits all lie in the same plane? and go round in the same direction?

Answer 78

The orbits all lie in the same plane, and the planets all go round in the same direction.

Question 79

There are many other members of our Solar System - what are they?

Answer 79

asteroids are much smaller than planets, and orbit the Sun. Most of the asteroids are between the planets Mars and Jupiter, but some come close to the Earth
moons orbit planets. Most are tiny. Only a few are as large as our Moon, which is nearly a sixth of the diameter of the Earth
comets have different orbits to those of planets, spending much of their orbital time far from the Sun. Comets are similar in size to asteroids, but are made of dust and ice.

Question 80

What forms the comets tail?

Answer 80

The ice melts when the comet approaches the Sun, and forms the comet’s tail.

Question 81

Nearly all of the mass in our Solar System is in the what? .

Answer 81

Nearly all of the mass in our Solar System is in the Sun.

Question 82

The sun is the source of nearly all energy we receive. What is the source of the sun’s energy ?

Answer 82

It is now understood that the nuclear fusion is the energy source. In nuclear fusion, smaller nuclei come together and form larger nuclei. For example hydrogen nuclei are joined together to make helium nuclei. This releases enormous amounts of energy.
hydrogen nucleus + hydrogen nucleus → helium nuclei

Question 83

why do scientists think that our planet was made from the remains of an earlier star?

Answer 83

In stars larger than our Sun helium nuclei can be fused together to create larger atomic nuclei. As the Earth contains many of these larger atoms, like carbon, oxygen, iron, etc, scientists believe that our Solar System was made from the remains of an earlier star.

Question 84

What is sun is the diameter of the sun compared to earth?

Answer 84

he Sun is very large. Its diameter is 109 times the Earth’s.

Question 85

the diameter of the Earth is ?

Answer 85

the diameter of the Earth is 12,800km (7,953 miles)

Question 86

the diameter of the Sun is ?

Answer 86

the diameter of the Sun is 109 times that of the Earth’s

Question 87

the Earth is how far from the Sun?

Answer 87

the Earth is 150 million km (93 million miles) from the Sun

Question 88

the distance to the nearest star is>

Answer 88

the distance to the nearest star is four light years.

Question 89

Rocks provide evidence for changes in the Earth. Who presented his idea of a rock cycle to the Royal Society and when? What were his ideas?

Answer 89

In 1785 James Hutton presented his idea of a rock cycle to the Royal Society. He detailed ideas of erosion and sedimentation taking place over long periods of time, making massive changes to the Earth’s surface.

Question 90

What makes massive changes to the earth’s surface?

Answer 90

He detailed ideas of erosion and sedimentation taking place over long periods of time, making massive changes to the Earth’s surface.

Question 91

Geologists can use other evidence from the rocks themselves such as:

Answer 91

looking at cross-cutting features
using fossils
deepness of the rock (younger rocks are usually on top of older ones).

Question 92

what are cross-cutting features? (rock that cuts across another is younger)

Answer 92

rock that cuts across another is younger)

Question 93

How do you get evidence that is more accurate about the age of rocks

Answer 93

radioactive dating

Question 94

When the magma oozing out of mid-ocean ridges solidifies into rock, the rock records what?

Answer 94

The typical speed of seafloor spreading is slow: about 10 cm per year. When the magma oozing out of mid-ocean ridges solidifies into rock, the rock records the direction of the Earth’s magnetic field. The Earth’s magnetic field changes with time, and sometimes even reverses its direction. These changes are recorded in the rocks. The same magnetic patterns are seen on both sides of the mid-ocean ridges.

Question 95

Magnetic changes are recorded in the rock. What happens to the Earth’s magnetic field with time?

Answer 95

The Earth’s magnetic field changes with time, and sometimes even reverses its direction. These changes are recorded in the rocks.

Question 96

Are the same magnetic patterns seen on both sides of the mid-ocean ridges?

Answer 96

yes