Space

Question 1

Name all the planets in the solar system in order from the sun?

Answer 1

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

Question 2

What orbit and shape are most planets in our solar system?

Answer 2

Each in an oval shaped with an elliptical orbit

Question 3

Name the rocky planets?

Answer 3

the four inner planets (Mercury, Venus, Earth and Mars), which are small, rocky, dense planets, close to the Sun;

Question 3

Name the gas giants?

Answer 3

the four outer planets (Jupiter, Saturn, Uranus and Neptune), which are large balls of gas, far from the Sun. They are called the gas giants.

Question 3

How were the inner planets formed?

Answer 3

When the solar system formed, rocks (and other dense, heavy materials in the dust cloud such as iron and uranium) tended to gather closer to the Sun, and these materials combined together to form the inner planets.

Question 4

How were the outer planets formed?

Answer 4

Lighter gaseous substances gathered together further away from the Sun and formed the outer gas giants

Question 4

What conditions must be met for a planet to from?

Answer 4

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

Its gravitational field must also be strong enough to ‘clear the neighbourhood’, pulling smaller nearby objects into its orbit.

Question 4

What is a moon?

Answer 4

A body orbiting a planet is called a satellite.

The Moon is a natural satellite that orbits planet Earth.

Many planets have moons, and some planets have many moons - Saturn has more than 50.

Question 5

What is dwarf planet?

Answer 5

Pluto is a dwarf planet.

The gravitational field of a dwarf planet is not strong enough to ‘clear the neighbourhood’, so there may be other objects in its orbit around the Sun.

Question 5

What is an asteroid?

Answer 5

Asteroids are made of metals and rocky material.

There are many asteroids in our solar system which orbit the Sun in oval or egg-shaped elliptical orbits which can take millions of years to complete.

There are large numbers of asteroids orbiting the Sun in the asteroid belt between Mars and Jupiter. There are also many in a region beyond Neptune called the Kuiper Belt.

Vary in size from a few meters to several hundred kilometers across.

Question 6

What is a comet?

Answer 6

Made of ice, dust and rocky material.

As a comet approaches the Sun, it begins to vaporise, which means that it turns into a gas, It then produces a distinctive tail.

Has an elongated orbit and is 1-30 km in diameter.

Question 7

What are differences between asteroids and comets?

Answer 7

Asteroids are made up of metals and rocky material.

Comets are made up of ice, dust and rocky material.

Both asteroids and comets were formed early in the history of the solar system about 4.5 billion years ago.

Question 8

What is an artificial satellite?

Answer 8

An artificial satellite is a man-made body placed in orbit round the earth or another planet in order to collect information about it or for communication purposes.

Question 8

What are artificial satellites sued for?

Answer 8

communications – satellite television and phone calls;

Earth observation - including weather forecasting, tracking storms and pollution, spying and satellite photography;

navigation - including the Global Positioning System (GPS);

astronomy – looking into outer space from our solar system.

Question 8

Types of artificial satellites?

Answer 8

polar orbits;
geostationary orbits.

Question 9

Explain polar orbits?

Answer 9

Polar orbits take the satellites over the Earth’s poles.

The satellites travel very close to the Earth - as low as 200 km above sea level, so they must travel at very high speeds - nearly 8000 m/s.

Question 9

Explain geostationary orbits?

Answer 9

Geostationary satellites take 24 hours to orbit the Earth, so the satellite appears to remain in the same part of the sky when viewed from the ground.

These orbits are much higher than polar orbits (typically 36,000 km) so the satellites travel more slowly (around 3 km/s).

Question 9

What are polar orbits used for?

Answer 9

Polar orbits are often used for earth-mapping, as well as for some weather satellites.

Question 10

What are geostationary used for?

Answer 10

Geostationary orbits are used for communication and broadcast satellites.

Question 11

When was the solar system formed and from what?

Answer 11

The Solar System was formed around 4.6 billion years ago from a giant cloud called a nebula, mainly made up of hydrogen gas and dust.

Question 12

Explain how our sun was formed from a nebula?

Answer 12

The nebula collapsed under its own gravity and, as it did, temperature and pressure increased.

It became denser and rotated more rapidly, spiralling inwards.

Eventually gravity compressed the hydrogen so much that the temperature reached about 15 million 0C.

At this temperature and pressure nuclear fusion began and our Sun was born.

Question 13

What is the hot core centre of a nebula called?

Answer 13

The hot core in the centre is called a protostar.

Question 14

What is accretion?

Answer 14

The collapsing and joining together of gas and dust under gravity is called accretion.

Question 15

Why is the sun stable?

Answer 15

The gravitational collapse inwards is balanced by the outward expansion due to heat and radiation pressure from the fusion reactions.

The Sun is expected to be a main sequence star for billions of years.

Question 16

What is the life cycle for a star with about the same mass as our sun?

Answer 16

Protostar - Main sequence star - Red Giant Star - White dwarf - Black dwarf

Question 17

What is the life cycle for a star with about greater mass than our sun?

Answer 17

Protostar - Massive Main sequence star - Red Super Giant Star - Supernova - Black hole or Neutron Star

Question 18

What is a red giant star?

Answer 18

When all the hydrogen has been used up in the fusion process, larger nuclei begin to form and the star may expand to become a red giant

Question 19

What is a white dwarf?

Answer 19

When all the nuclear reactions are over, a small star like the Sun may begin to contract under the pull of gravity. In this instance, the star becomes a white dwarf which fades and changes colour as it cools.

Question 19

What is a supernova?

Answer 19

An explosion in which the outer layers of the star are ejected. The star will shine as supernova for a relatively short period of time with the brightness of 10 billion suns. After the supernova the remaining core of the star may collapse further.

Question 20

What is a black hole

Answer 20

Rather, it is a great amount of matter packed into a very small area. A black hole is made when the centre of a very big star falls in upon itself, or collapses. All the matter of the star becomes squeezed into a tiny space and the force of gravity increases greatly. There is such a strong gravitational field in a black hole that nothing can escape from it, including electromagnetic radiation such as light.

Question 21

When does a black hole or neutron star from?

Answer 21

Depending on the mass at the start of its life, a supernova will leave behind either a neutron star or a black hole.

Question 22

What is nuclear fusion?

Answer 22

In a main sequence star, hydrogen nuclei fuse together to form helium nuclei. Two hydrogen nuclei fuse to produce a helium nucleus and a neutron

Question 22

What evidence is there that earth was formed from a supernova?

Answer 22

The presence of gold and other heavier elements such as uranium in the Earth is evidence that the solar system was formed from the remains of a supernova.

Question 23

What evidence is there that our solar system was formed at the same time?

Answer 23

The orbits of the planets are more or less in the same plane They all revolve around the sun in the same direction.

Question 24

What is a centripetal force?

Answer 24

Any force which causes objects to move in a circular path is called a centripetal force.

Question 24

How are the orbits of the inner and outer planets different?

Answer 24

The orbits of the inner planets are almost circular but that of the outer planets are much more elliptical.

Question 25

How does the centripetal force increase?

Answer 25

* The mass m of the object increases * The speed v of the object increases * The radius r of the orbit decreases

Question 26

What is the history of the heliocentric model?

Answer 26

Copernicus in the early part of the sixteenth century proposed the heliocentric model In 1610 Galileo Galilei used a telescope to record observations of the stars and planets and his work supported the sun centred model proposed by Copernicus but that many opposed his views. Then in June1633 the Roman Catholic Inquisition forced Galilei to recant his publicsupport for the heliocentric model

Question 26

What models for our solar system were accepted and now used?

Answer 26

The first accepted model of the solar system was the Geocentric Model (with the earth at the centre) a model which was accepted as true for almost 2000 years as opposed to the Heliocentric Model (with the sun at the centre instead of the earth) which is now the accepted model,

Question 26

When did the church change its mind on the heliocentric model?

Answer 26

1992 and the church changed its position and admitted that the Solar System is heliocentric.

Question 27

How long is our sun going to be stable for?

Answer 27

Note that in a star this state lasts for 10000 million years and that the sun is about halfway through this stage in its life cycle.

Question 28

How many stars are in our galaxy and what is it called?

Answer 28

There are about 100 000 000 stars in our galaxy which is called the Milky Way

Question 29

When was the Big Bang?

Answer 29

It is estimated that the Big Bang occurred 12 – 15 billion years ago.

Question 29

What shape is the Milky way and where is our solar system?

Answer 29

Milky Way is a slowly rotating spiral shaped galaxy and that our Solar System is close to the ends of one the arms of the spiral

Question 30

Explain the doppler effect?

Answer 30

If the object is moving towards an observer, the waves are shifted to a higher frequency, shorter wavelength. If the object is moving away from an observer, the waves are shifted to a lower frequency, longer wavelength. This happens with light as well as sound.

Question 30

Astronomers have found that the further from us a star is, the more its light is red-shifted, what does this mean?

Answer 30

The further away a galaxy is, the faster it is moving away.

Question 31

What is a red shift?

Answer 31

Light is shifted towards the long wavelength, red end of the spectrum. - other galaxies are moving away from our galaxy; - the Universe is expanding.

Question 32

What is the evidence for the big bang?

Answer 32

1. Galaxies should move outwards. Light from stars in other galaxies is red-shifted, this indicates that other galaxies are moving away from ours. 2. More distant galaxies should move away faster. More distant galaxies have greater red-shift, this indicates that more distant galaxies are moving away faster than nearer galaxies. 3. Heat energy left over from the Big Bang should now be thinly spread across the whole Universe. CMBR is everywhere at a temperature of about -270°C. CMBR is the remains of the heat energy from the Big Bang, spread thinly across the whole Universe.

Question 33

What is the big crunch?

Answer 33

If the gravitational pull of all the galaxies is strong enough it might stop the galaxies moving away from each other and pull them back together so that at some stage in the distant future there might be a ‘big crunch’ as all the matter in the Universe collapses to meet and collide at one point

Question 34

What is a big bounce?

Answer 34

In this model the ‘Big Crunch’ is followed by the ‘Big Bang ‘of a new Universe and this eventually stops expanding and contracts so that another ‘Big Crunch’ occurs followed by another ‘Big Bang’ giving a cyclical universe An accelerating Universe suggests that this is not the most likely outcome.

Question 34

What is a big freeze?

Answer 34

In this scenario the universe continues to expand and run down and with entropy increasing that over a scale of 1014 years that the temperature across the Universe would approach 0K. The Universe would be too cold to sustain life. All that would remain would be burned out stars, cold dark planets and black hole.

Question 35

When was the first artificial satellite launch and when was the first person who travelled around the earth in a spacecraft?

Answer 35

Note that the first artificial satellite was launched into earth orbit in October 1957 Note that the first person travelled in a spacecraft around the earth in April 1961

Question 36

When did we first visit the moon?

Answer 36

1969 three astronauts travelled the 400 000 km journey to the moon which took four days and that two of them Neil Armstrong and Edwin (Buzz) Aldrin walked on the surface of the moon.

Question 37

Explain the limitations of space travel?

Answer 37

The nearest star to Earth, Proxima Centauri, is about 4 x 1013 km or 40 trillion km away. The speed of space travel is too slow. With present technology it would take over 81,000 years to travel between Earth and Proxima Centauri. There are problems of logistics – how to carry enough food, water, oxygen water and fuel to make long flights possible. Costs are very high. Leaving planet Earth is an expensive business because of the technology involved. Long periods of weightlessness is not good for the human body. It brings about muscle wasting and bone loss. It can also stop some important cells doing their job properly also Space radiation can cause cancer and is hard to shield against.

Question 37

What has the Hubble done and how?

Answer 37

Note that the Hubble Space Telescope has allowed us to find out that some other stars have planets which orbit around them. This has come about by close observation of stars whose light has been changed because of the presence of an orbiting planet.

Question 38

What project searches for extra-terrestrial life?

Answer 38

SETI Project (Search for Extra-Terrestrial Intelligence) involves many scientists using radio telescopes to search for meaningful radio signals. The SETI Project has recruited people from around the world to use their home computers to help in the analysis of radio signals from distant galaxies.

Question 39

What happens to the luminosity and frequency of hot objects as their temperature increases?

Answer 39

All hot objects, including stars, emit a continuous range of radiation in the electromagnetic spectrum. The luminosity (brightness) and peak frequency of this radiation increases as the temperature of the object increases

Question 40

How frequencies of pure elements relate to colour.

Answer 40

When atoms in a pure element are excited (given lots of energy) they give off light at fixed and characteristic frequencies. These frequencies directly relate to the colour - from low frequency infrared, through the visible spectrum, and up to high frequency ultraviolet.

Question 41

What are emission line spectra?

Answer 41

These emission line spectra are like a chemical fingerprint for that element. They are caused by the movement of electrons between energy levels in the atoms. Hydrogen has the simplest emission spectrum.

Question 41

How do we know hydrogen is present in the sun?

Answer 41

The gaps in the spectrum from the Sun correspond exactly to the lines in the emission spectrum for hydrogen. This means that there is hydrogen present in the Sun, which is absorbing light of specific frequencies.

Question 42

How do emission line spectra allow us to establish if life is possible on certain planets.

Answer 42

If there is to be life on another planet, then the element oxygen must exist in their atmosphere. Thus, the presence of oxygen, which can be detected from the light from these distant galaxies / planets, enables us to establish if life is possible or not.

Question 42

What is a light year?

Answer 42

The distance light travels in a year

Question 43

How is the distance of one light year calculated.

Answer 43

As light travels at constant speed, the distance light travels in a year can be calculated using the equation: Distance = speed x time Speed of light = 300,000,000 m/s = 3 x 108 m/s time = 1 year = 365 x 24 x 60 x 60 = 31,536,000 s 1 light year = 3 x108 m/s x 31,536,000 s = 9.46 x 1015 metres 1 light year = 9.46 x 1015 m

Question 44

What distance is one light year?

Answer 44

1 light year = 9.46 x 1015 m

Question 45

What evidence supports that our solar system was formed from the same large nebular?

Answer 45

Orbit in the same direction and on the same plane