Earth, Moon, Sun interactions

Question 1

Why do the sun and the moon appear to be the same size in the sky?

Answer 1

Because the angular size of the Sun and the Moon are exactly the same from the Earth (coincidence).

Question 2

Why do we not have a total solar eclipse every month?

Answer 2

The Ecliptic and the plane of Moon’s orbit around Earth are different.

Question 3

Describe a total solar eclipse.

Answer 3

• Occurs at new moon.
• The Moon passes directly in front of the Sun.
• Light from the Sun’s photosphere obscured if observer is in the umbra.

Question 4

What are Bailey’s Beads?

Answer 4

• Small bright spots of sunlight caused by Sun’s rays shining through valley’s on the Moon
• At the beginning and end of totality.
• Diamond ring effect.

Question 5

Describe a partial solar eclipse.

Answer 5

Moon only partly obscures light from the Sun. i.e. Earth’s surface lies in penumbra.

Question 6

What is a lunar eclipse?

Answer 6

• Occurs at full moon
• When Earth passes between Sun and Moon.
• Moon given reddish glow.

Question 7

What type of eclipse is most common and why?

Answer 7

A lunar eclipse because it is visible from most of the Earth’s Night Side.

Question 8

Why does the Moon appear red during a Lunar eclipse?

Answer 8

Because “blues bend best.”

Light from the Sun is refracted by the Earth’s atmosphere.

Question 9

In which direction does the Earth spin?

Answer 9

From west to east

Anticlockwise when observed looking down on the North Pole.

Question 10

What is a Sidereal Day?

Answer 10

• The actual time it takes for Earth to spin 360 degrees on its axis.
• The time taken for successive crossings for a given star across the observer’s meridian.
• It is 23h 56 min and 4.1 seconds.

Question 11

What is a Solar Day?

Answer 11

• This is exactly 24 h
• the time taken for successive crossings of the Sun across the Observer’s Meridian
• An extra 4 minutes is needed because the Earth has move slightly in Its orbit around the Sun.

Question 12

Name the Aurorae.

Answer 12

Aurora Borealis (Northern Lights)
Aurora Australis (Southern Lights)

Question 13

What causes the Aurorae?

Answer 13

• Electrons in the Solar Wind are accelerated by the Earth’s magnetic field at the poles.
• Atoms of Nitrogen and Oxygen in the upper atmosphere become excited.
• As they de-excite they emit particular wavelengths of light.