Term
| What percent of the Earth is water? |
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Definition
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Term
| What percentage of the Earth is land? |
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Definition
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Term
| Give 3 reasons why life on Earth exists. |
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Definition
- We have a magnetic field which deflects solar particles from the Sun.
- Our atmosphere also absorbs harmful rays from space.
- Our planet is positioned in a habitable zone, where water can exist as a liquid to support life. This is a region far enough from the Sun to stay warm, but not near enough to evaporate.
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Term
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Definition
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Term
| Give 5 reasons why astronomers knew that the Earth was round. |
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Definition
- The Moon is round
- The shadow of the Earth on the Moon during a lunar eclipse is round
- Travellers going north or south see different stars not visible from elsewhere
- Travellers recording shadows at different angles on the same date
- Tall ships appear to 'sink' as they move over the horizon
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Term
| Who was Eratosthenes and what did he did he discover? |
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Definition
| Eratosthenes was a Greek mathematician and the librarian of Alexandria in Egypt. He learnt that in the town of Syene, to the south, the Sun appears at the zenith (the highest point in the sky) on the summer solstice – it was well know that its reflection could be seen directly down a deep well. By observing and measuring shadows in Alexandra, he calculated that the Sun was over 7.12 degrees from the Zenith on the same date. This is approximately 1/50th of a circle. |
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Term
| What is the Rotation Time of the Earth and what is this known as? |
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Definition
| 23 hours, 56 minutes known as the Siderial Day |
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Term
Why do we see the Sun rise in one place and set in another? |
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Definition
| Because the Earth goes around the Sun and rotates on its axis East to West. |
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Term
| Explain the term - 'Tropics' |
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Definition
A region where the Sun is directly overhead in the zenith at least once a year, and lie between approx. 23.5N & S. |
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Term
Explain the term - 'Equator' |
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Definition
| The line of latitude directly through 0o . The area above the equator is called the Northern Hemisphere and the area below is called the Southern Hemisphere. |
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Term
Explain the term - 'Latitude' |
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Definition
| How far North or South a position is. Measured from 0o at the equator and 90o+ at the North Pole or 90o- at the South Pole. |
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Term
Explain the term - 'Longtitude' |
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Definition
| How far East or West a position is. Measured from 0o at the meridian and 180o+ Eastwards or 180o- Westwards. |
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Term
| Explain the term - 'Poles' |
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Definition
| The pole is a point on the surface of the Earth at the axis of rotation, and both poles are located at 90o from the equator. |
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Term
| Explain the term - 'Zenith' |
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Definition
| The Zenith is a point directly above the observer's head. The opposite of Zenith is the Nadir, the point directly below the observers feet. |
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Term
| Explain the term - 'Horizon' |
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Definition
| The horizon is the furthest visible point of the Earth's surface from the observer's position. |
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Term
| Explain the term - 'Meridian' |
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Definition
| An imaginary line intersecting the pole to the observer's zenith. |
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Term
| State three benefits of the Earths Atmosphere. |
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Definition
1. Oxygen allows humans and animals to breathe
2. Protects us from harmful ultraviolet radiation from the sun
3. Makes the climate and temperature of the Earth consistent
Other points may include:
1. It spreads and scatters light from the sun
2. Protects us from micro meteorites collisions |
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Term
| State three drawbacks from the Earths atmosphere. |
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Definition
1. It holds greenhouse gases that retain the heat of the sun which is necessary for life on Earth however the man made gases contribute to global warming
2. Clouds regulaly obscure astronomical viewing
3. It refracts light which makes inaccurate observations of stars
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Term
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Definition
White light is made up of 7 different colours red,orange, yellow, green, blue, violet & indigo. This light travels at different wavelenghts. Some colours are better at passing through gases (red - longwavelength, indigo - shortestwavelength). When protons from the sun travel into our atmosphere some of this light (blue, violet & indigo) bounce off the nitrogen and Oxygen therefore light is scattered. As a result of this we see blue as it is more dominent than violet & indigo. |
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Term
| What is Optical Pollution? |
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Definition
| Light from human sources that obscures the view of the night sky. |
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Term
| What is Chemical Pollution? |
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Definition
Man-made and natural chemicals that obscure the night sky.
Human Pollution comes from manufacturing and production industries etc
Natural Pollution comes from volcanoes and gases from the mantle passing through the crust into the atmosphere. |
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Term
| What is the order of the electromagnetic spectrum largest to smallest? |
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Definition
| Radio waves, Infared waves, Visible light, Ultraviolet, X rays, Gamma rays. |
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Term
| What is a Refractor Telescope? |
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Definition
| A convex lens at the end of a tube to bring an image into focus at a point. Another convex lens (eye piece) is used at the opposite end of the tube to magnify the image. |
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Term
| What is a Reflector Telescope? |
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Definition
| It is a telescope that collects light at one end of a tube and reflects it off a concave mirror. It is brought to a focus by a secondary mirror at a 45o and magnified using an eye piece. |
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