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PLANET EARTH

LEARNING OUTCOME

Describe and explain what planet Earth would look like from space.

Planet Earth and astronomy resources. Click here to open and select any resources you need.

From space planet Earth looks like a blue and white disc against a starry background. The colour comes from the world’s oceans which reflect the blue colour back into space. The white colour comes from the clouds. The clouds are just huge amounts of water vapour existing as very tiny droplets in the atmosphere.
Also visible is the brown and green of the world’s continents.

The shape of the Earth is a geoid. This means it is a sphere which is slightly squashed as if someone was pressing against both the North and South poles. Only half of the Earth is lit up at any onetime, this is because planets do not produce their own light and the Earth is relying on the Sun for its light. The planet therefore is reflecting the Sun’s light back into space, making Earth appear illuminated from outer space. 

The earth is spinning like a top. It rotates about its axis which runs from the north to the south. The Earth is slightly tilted at an angle of approximately 23°. The Earth
takes one day to rotate about its axis and 365% days to orbit the Sun. This is why we have a leap year. We don’t have Y4 of a day so we catch up the day every 4 Earth
years. The orbital path around the Sun is 24 hours elliptical in shape.

The Earth is the only place in our solar system that we know has life. Its unique position in terms of the distance from the Sun means water can exist as a liquid. This is essential for life to exist.

SUN

Energy travels from the Sun to Earth. Mainly as light and heat, which is what we notice.

                         
The side of Earth that faces the Sun is in daytime.  The other side that faces away is in night time.

The Earth is spinning like a top. It rotates about its axis which runs from the north to the south. The Earth is slightly tilted at an angle of approximately 23°. The Earth takes one day to rotate about its axis and 365% days to orbit the Sun. This is why we have a leap year. We don’t have 0.25 (one quarter) of a day so we catch up the day every 4 Earth years. The orbital path around the Sun is 24 hours elliptical in shape.

The Earth is the only place in our solar system that we know has life. Its unique position in terms of the distance from the Sun means water can exist as a liquid. This is essential for life to exist.

Planet Earth Crossword

The Earth takes 365.25 days to orbit the Sun in an elliptical orbit.

Learning Outcome

Describe and explain the seasons and tides of planet Earth.

The Seasons
The seasons are determined entirely by the tilt of the Earth which is at an angle of approximately  23° to the vertical. This means over the course of a year the angle facing the Sun changes by  approximately 23°. As a result the Sun is higher in the sky over the southern half of the Earth for half  of the year. The days are longer and the nights are shorter. During the other half of the year the Sun  is lower in the sky meaning that days are shorter and the nights are longer. Accordingly there is less  warming during winter because of the shorter days. The angle of tilt also means during winter that  the Sun’s rays have farther to travel and therefore aren’t able to warm the Earth as much as they can  during summer.

Southern Winter (The sun is not directly overhead  in the middle of winter and the  sunlight travels and spreads over  a greater distance.) Equator Southern Summer (The sun is directly overhead  in the middle of summer.) 23° Moon’s Gravitational Pull / Sun’s Gravitational Pull

 

The Tides
The tides are caused mainly by the  influence of the moon. The Sun also  has an effect but to a lesser degree.  The tides are caused because of the  gravitational pull of the Moon pulling  the water towards it. As the Moon  orbits the Earth the rising water  follows the Moon around. A spring  tide occurs every few weeks when the  Sun and the Moon are both aligned  together on one side of the Earth  and they are pulling together. The  gravitational pull of the Moon has  very little effect on the land.

Learning Outcome 

Understand the position and movement of planet Earth within the solar system.

 

The Earth is orbiting the Sun. The Earth is therefore a satellite of the Sun. The Earth takes 365.25  days to orbit the Sun and is just under 150 million kilometres away from the Sun on average.  The orbital path around the Sun is not a circle but is in fact an ellipse. One rotation or orbit around  the Sun is the time we have defined as one year. The midway point between the summer and  winter seasons during the year are called the solstices.

The Earth is the third planet from the Sun and is one of the eight planets of the solar system.  The solar system is composed of 4 inner planets and 4 gas giants. The inner planets in order from the Sun are:

• Mercury            • Venus             • Earth             • Mars

The gas giants in order from the Sun but further from the Sun than the inner planets are:

• Jupiter             • Saturn             • Uranus             • Neptune

The Earth has one natural satellite which is called the Moon. The gravitational pull of the Moon  is 1/6th that of the Earth because the Moon is much smaller than the Earth. The Earth is a large  spinning sphere in space, but is slightly squashed inwards at the poles. This near-spherical shape  is called a geoid. The Earth is tilted at an angle of approximately 23° from its axis. This angle of  rotation of the Earth means that during one half of the year one hemisphere of the Earth is tilted  closer to the Sun. During the other half of the year the other hemisphere is tilted closer to the Sun.  This explains why we have seasons.

The Earth is rotating on its axis eastwards at approximately 1600 kilometres per hour. This speed  of this rotation is not noticeable because everything is travelling along with the Earth at the same  speed. One complete rotation of the Earth on its axis takes almost 24 hours. During this rotation  one side of the Earth will be dark and the other side will be in sunlight. This explains why we have  night and day.

The top and bottom regions of the Earth are called the North and South poles. The North Pole is  called the Arctic and the South Pole is called Antarctica. They are very cold as they don’t receive any  direct sunlight. This explains the ice and snow of these regions as the Sun has a very limited heating  effect. Direct sunlight does heat up other areas of the Earth such as the equatorial regions where the  Sun is almost directly overhead. Because of the distance from the Earth to the Sun light from the Sun  takes approximately 8 minutes to reach the Earth.The sunlight is travelling at 3 x 10^8 m/s.

The gravitational attraction of the Moon, but also to a lesser degree the Sun, causes the Earth’s  tides. The Earth’s oceans are pulled by gravity to the Moon as the Moon orbits the Earth. This causes  the rise and fall of the oceans.