Unit 3- Earth-Moon-Sun System

Question 1

How did Aristarchus find the distance of the Earth to the Moon?

Answer 1

He noticed that when he held his thumb up at arms length he could cover the Moon’s disc.
Therefore, he made an equation that was- tan 1= radius of the moon/ distance to the moon.
Thus, d= radius of the moon/ tan 1
1760/ tan 1= 1.008* 5 to the power of 5 to 3 sig figs
Or, 100800km

Question 2

What is the mean diameter of the Sun?

Answer 2

1*10 to the power of 6

Question 3

How was the size of the moon discovered?

Answer 3

U1-U2= time taken for the Moon to move through its own diameter
U1-U3 or U2-U4= time taken for the Moon to move through the Earth’s diameter
SO. U1-U2/U3-U4= diameter of the Moon/ diameter of the Earth
So, the moon was around 0.32-0.4 times smaller than the size of the earth
In modern days, it was discovered to be 0.27

Question 4

What is the mass of the: Earth, Moon and Sun?

Answer 4

Earth= 5.6* 10 to the power of 24
Moon= 10 to the power of 22
Sun= 10 to the power of 30

Question 5

What does it mean for the Moon to wax or wane?

Answer 5

When it waxes, it means that it ‘grows’
When it wanes, it means that it ‘shrinks’

Question 6

What are tides?

Answer 6

They are the periodic rising and falling of large bodies of water. Wind and currents move the surface, which causes waves.

Question 7

How are tides formed?

Answer 7

Gravitational attraction of the moon causes oceans to bulge up in the direction of the moon, and another one bulges out on the opposite side because the Earth is also being pulled towards the moon (and away from the water on the far side)

Question 8

Why are there 2 tides per day?

Answer 8

Moon travels around Earth, they both orbit the sun. Combined gravitational force makes the world’s oceans rise and fall. It happens twice because the Earth if rotating while this is happening.

Question 9

Why are there 2 tides per day?

Answer 9

Moon travels around Earth, they both orbit the sun. Combined gravitational force makes the world’s oceans rise and fall. It happens twice because the Earth if rotating while this is happening.

Question 10

When do SPRING TIDES happen (what PHASE OF THE MOON)

Answer 10

During a FULL or HALF moon

Question 11

What are spring tides?

Answer 11

When the high tides are very high and low tides are very low. They are also known as strong tides, and they occur when the Earth, Sun and Moon are in line. Gravitational forces from the Moon and Sun both contribute to the tides.

Question 12

What are spring tides?

Answer 12

When the high tides are very high and low tides are very low. They are also known as strong tides, and they occur when the Earth, Sun and Moon are in line. Gravitational forces from the Moon and Sun both contribute to the tides.

Question 13

When do NEAP TIDES occur (what PHASE OF THE MOON)

Answer 13

During the QUARTER PHASES

Question 14

Describe what happens in neap tides

Answer 14

The Sun and Moon are at right angles so the bulges in the sea cancel each other. This means there is a smaller distance between high tides and low tides, AKA neap tides. They are especially WEAK. They occur when the gravitational forces of the Moon and Sun are perpendicular to one another.

Question 15

How long is Earth’s precession?

Answer 15

25,772 years (26,000 years)

Question 16

What is precession?

Answer 16

Gravity induced slow and continuous change in the orientation of an astronomical body’s rotation axis

Question 17

What are the effects of precession?

Answer 17

1.) Positions of the SCP and the NCP appear to move in circles against the backdrop of the stars, completing one circle every 25,772 years.

Question 18

What are the effects of precession?

Answer 18

1.) Positions of the SCP and the NCP appear to move in circles against the backdrop of the stars, completing one circle every 25,772 years. This means that Polaris isn’t the permanent ‘north star’, and that over time there will be a different ‘north star’
2.) The Earth’s rotation on its axis has a slight “wobble”, and it takes around 26,000 years to complete a 360 degree “wobble”. This is known as PRECESSION OF THE EQUINOXES or AXIAL PRECESSION

Question 19

What are the causes of precession?

Answer 19

1.) Earth being an oblate spheroid
2.) Interaction with complex gravitational fields of the Sun and Earth, causing “wobbling” of the Earth’s axis

Question 20

How often are star positions republished?

Answer 20

Every 50 years

Question 21

What does Right Ascension (RA) mean?

Answer 21

The method of indicating a Star’s direction from the Earth

Question 22

What is the effect of precession on a star’s RA?

Answer 22

It will cause a slight shift, meaning the stars will slowly change direction from the Earth

Question 23

What are solar eclipses?

Answer 23

The MOON COMPLETELY BLOCKS THE SUN in perfect alignment BETWEEN the Earth and the Sun. The SHADOW OF THE MOON passes over certain parts of the Earth so a total solar eclipse can be seen

Question 24

What phase does the moon have to be for a solar eclipse to happen?

Answer 24

NEW MOON

Question 25

What is a lunar eclipse?

Answer 25

When the SUN EARTH and MOON ALIGN WITH EARTH IN BETWEEN and the Moon passes into the EARTH’S SHADOW. It’s not black, but reddish copper, making it a BLOOD MOON

Question 26

Why does the moon turn red during a total lunar eclipse?

Answer 26

The blue light gets scattered outwards, and the red wavelengths are refracted, thus bent inwards.
NOTE: THE SHORTER THE WAVELENGTH, THE HIGHER THE FREQUENCY
shortest wave length to longest wavelength= Violet, Indigo, Blue, Green, Yellow, Orange, Red

Question 27

When is a partial lunar eclipse occurring?

Answer 27

When the Moon passes into the Earth’s umbra, and into the penumbral shadow

Question 28

Where does the observer have to be to observe: 1.) A solar eclipse 2.) A partial solar eclipse

Answer 28

1.) In the umbra
2.) In the penumbra

Question 29

What is a: 1.) Photosphere 2.) Corona 3.) Chromosphere 4.) Prominences

Answer 29

1.) The visible side of the sun
2.) Sun’s outer atmosphere
3.) Portion of the Sun’s atmosphere located between the photosphere and the corona
4.) Eruptions occurring on the solar surface

Question 30

What happens during an annular eclipse?

Answer 30

The sun’s photosphere is visible as a bright ring around the moon’s edges

Question 31

Why do annular eclipses occur?

Answer 31

The moon is in the apogee of it’s orbit, meaning it’s further away from the Earth