Physics
- Created by: Quincy Washington
- Created on: 07-05-10 20:21
Why did people think that the Earth was the centre of the universe?
-The Sun, Moon and Stars seemed to orbit around the Earth.
What is a sidereal day?
-The time taken for a star to return to the same position in the sky.
How long is a sidereal day?
-23 hours and 56 minutes
For a star to get to the same position in the sky, what degree does the Earth have to spin?
-360°
The Sun and Moon appear to cross the sky at different ******.
-Speeds
The Sun and Moon appear to cross the sky from **** to ****.
-East to west
The Sun seems to move **** slowly across the sky than distant stars.
-More
What is a solar day?
-The time taken for the Sun to appear at the same position in the sky.
How long is a solar day?
-24 hours
How much longer is a solar day compared to a sidereal day?
-4 minutes longer
Why are solar and sidereal days different?
-The Earth orbits the Sun as well as spinning on its axis.
Why does the Earth need to spin slightly more than 360° before the Sun appears at the same position in the sky?
-The Earth orbits the Sun in the same direction as it spins.
How long does it take for the Moon to appear at the same position in the sky?
-25 hours
Why does it take the Moon longer to appear at the same position in the sky than the Sun?
-The Moon orbits the Earth in the same direction as the Earth is rotating.
As the Earth moves around the Sun, the direction we face changes slightly each ***.
-Day
What is an Earth year?
-The time it takes the Earth to orbit the Sun once.
“We can see a different patch of sky each night – we see different stars” – True or False?
-True
How does the moon glow?
-Reflects light from the Sun.
What fraction of the moon is lit up, and what fraction is shadow?
-50/50
What sort of moon do you see when the whole of the –lit-up surface is facing the Earth?
-Full moon
What sort of moon do you see when the dark half faces us?
-New moon
When do eclipses happen?
-When light from the sun is blocked
What is a lunar eclipse?
-No direct sunlight can reach the Moon.
What is a solar eclipse?
-When the Moon blocks out the sunlight.
Why don’t eclipses happen often?
-The Moon is at a slight angle to the Earth’s orbit around the Sun. So the Sun, Moon and Earth do not line up to cause a lunar or solar eclipse.
Why do partial eclipses happen more often than total eclipses?
-The Sun, Moon and Earth do not have to line up perfectly in partial eclipses.
How are the positions of star measured?
-Angles seen from the Earth.
What are the 2 fixed positions that astronomers measure from?
-The Pole Star, the…
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