Physics

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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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