Chapter 5 - The Earth in Space Flashcards
How does day and night work?
The Earth spins on its axis. This means that the area which is exposed to light and area which is not are caused by the Earth spinning every 24 hours.
The Earth rotates from west to east so we see the sun rise in the east and set in the west
How can we use a Foucault pendulum to show the spinning of the Earth?
A scientist called Leon Foucault made a pendulum with a 67m long pendulum with a mass of 28 kg. He hung the pendulum off a tall building so that it was only 1m from the ground and then swung the pendulum. The pendulum swung for a long time as it was so heavy and over time, the direction of the swing seemed to change against a scale on the floor. The only explanation was that the pendulum was swinging in the exact same way but the earth was spinning underneath it.
What are seasons?
We divide the 365 days on Earth into four season; summer, winter, autumn and spring. In countries near the poles, there is a big change between summer and winter but near the equator, there isn’t much difference.
How can we explain seasons?
Seasons happen because of the Earth’s axis, with tilt of 23.5 degrees. The tilt doesn’t change, so for 6 month the north pole is tilted towards the sun and for the rest 6 months, the south pole is tilted towards the sun.
What does the Earth’s axis explain?
The Earth’s axis explains:
1. Different day lengths in Summer and Winter
2. Different temperatures in summer and winter
3. The varying height of the SUn in the sky in summer and winter.
Does the length of the day change?
Yes, when an area goes from summer to winter, the days get shorter and the sun starts hitting at and angle.
The tilt of the axis means that in regions in the arctic circle and in antarctica, the sun doesn’t set in the summer. These places are known as the land of the midnight sun. In winter, in these places the sun does not rise at all, we call this a polar night.
Why does the temperature change?
The temperature is hotter in the summer because the sun is in the sky for longer and the sun’s rays are concentrated over a smaller area, at a 90 degree angle. This means that the surface heats up faster and the temperature increases more quickly, as more energy hits the surface.
Why does the height of the sun change in the sky?
This happens because of the Earth’s tilted axis.
Why do the stars flicker at night?
Stars flicker at night because the light changes direction when it travels through the Earth’s atmosphere.
What are planets?
Planets are objects that are in orbit around stars. You can see Mercury, Venus, Mars, Jupiter, and Saturn with a naked eye but you can’t see Uranus and Neptune.
What is a moon?
The moon is made of rock and orbits the Earth. It is an object that orbits a planet. It is called a natural satellite. Moons can be big or small. It is seen through reflected light.
What are comets?
A comet is an object which orbits the sun, it is made from ice and dust. We can see it through reflected light. Some comets come back again and again.
What are meteors and meteorites?
When a particle of dust or a piece of rock called a meteor enters the Earth’s atmosphere, it burns up. A piece of rock that survives to the ground is called a meteorite.
You see a meteor shower when the Earth moves through the dust left by a comet.
Tiny meteorites hit the surface of the Earth all the time. If you go outside about a dozen will land on you every hour.
What are man-made objects in the sky?
There are thousands of artificial satellites orbiting the Earth, many are part of the Global positioning System, which pinpoints locations on Earth using many satellites. You can sometimes see these satellites near dawn or dusk when they reflect light from the sun. The biggest and brightest of all of these is the International Space Station.
What does our solar system contain?
Our solar system contains four inner planets, four outer planets, ann asteroid belt and some dwarf planets in the asteroid belt and beyond the outer planets.
