Earth, stars, galaxies and space Flashcards

Question

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 1

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.

Answer 2

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

Answer 3

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.

Answer 4

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.

Answer 5

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.

Answer 6

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.

Answer 7

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

Answer 8

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.

Answer 9

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.

Answer 10

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.

Answer 11

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.

Answer 12

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.

Answer 13

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

Answer 14

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?

Answer 15

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.

Answer 16

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.

Answer 17

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.

Answer 18

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.

Answer 19

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

Answer 20

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

Answer 21

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.

Answer 22

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

Answer 23

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.

Answer 24

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

Answer 25

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.

Answer 26

The distance travelled by a wave is calculated using this equation: Distance = speed x time

Answer 27

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.

Answer 28

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

Answer 29

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.

Answer 30

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.

Answer 31

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.

Answer 32

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.

Answer 33

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.

Answer 34

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.

Answer 35

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.

Answer 36

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

Answer 37

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.

Answer 38

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.

Answer 39

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

Answer 40

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

Answer 41

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.

Answer 42

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.

Answer 43

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.

Answer 44

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.

Answer 45

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.

Answer 46

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

Answer 47

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.

Answer 48

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

Answer 49

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.

Answer 50

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

Answer 51

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.

Answer 52

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.

Answer 53

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

Answer 54

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

Answer 55

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.

Answer 56

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

Answer 57

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

Answer 58

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

Answer 59

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.

Answer 60

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

Answer 61

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

Answer 62

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

Answer 63

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

Answer 64

the distance to the nearest star is four light years.

Answer 65

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.

Answer 66

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

Answer 67

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

Answer 68

rock that cuts across another is younger)

Answer 69

radioactive dating

Answer 70

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.

Answer 71

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