Topic 3- The Earth Moon Sun System Flashcards
What causes tides
The gravitational attraction of the moon and sun pulls on earth the water on earths surface is pulled and the water causes tides
What causes high and low tides
The moon pulls water on earths surface nearest it and there is a force equal to this on the other side of the earth pulling the water out
What causes spring tides
When the sun moon and earth are in a line there are more dramatic differences in tides high tides are higher and low tides are lower
What causes neap tides
When the moon is at a right angle to earth then tides are less dramatic high tides are lower and low tides are higher
How long is a cycle of precession
26000 years
What causes precession
As the earth is not a perfect sphere and the sun and moon have a gravitational influence on earth and this combined with the earths bulge causes a wobble in earths tilt
What has precession caused
The celestial pole star to move and change and the sun to rise at a different time
How many times further away is the sun from us that’s the moon
400 times
How many times smaller is the moon that the sun
400 times
What is the mean diameter of sun
1400000 km
What is the average distance of the moon from earth
385000
What is the average distance of sun from earth
150 million
‘What type of stars had a special place in ancient Egyptian culture
Circumpolar stars
What did circumpolar stars mean to ancient Egyptians
As the stars were always in the sky it symbolised a place of heaven and the afterlife
Why were small shafts in the pyramids align with circumpolar stars
So the pharaoh buried inside spirit could go to the after life
On the pyramid Where did the shafts point to
The rotation path of Orion and the old NCP Thuban
What is new grange
Located in Ireland and is the site of an ancient burial ground built 5000 years ago
When does light enter the passage at new grange
4 minutes after sunrise on the winter solstice
When would the light of entered the passage at new grange when it was built
At exactly sunrise on the winter solstice
What was Stonehenge used to mark
It is highly likely to have been used to mark the sunrise of the summer solstice
What is an eclipse
When the shadow of a celestial body such as the earth or moon obscures the light of another object in space
What are the 2 main types of eclipse
A solar eclipse
A lunar eclipse
When do eclipses occur
When the sun moon and earth are lined up with one another
What is the term used for 3 or more celestial objects are aligned
Syzygy
What time of phase does the moon need to be in for an eclipse to happen
Full and new
How many times does the moons orbit intersect the ecliptic during one orbit
Twice an orbit
How far away is the moon eclipses from the ecliptic
5%
What is the term used when the moons orbit intersects with the ecliptic
Nodes
Where do the nodes go from
One goes from north - south and is called the descending node
One goes from south to north and is called the ascending node
How long does a solar eclipse last
Up to 7 minutes and 30 seconds
How long does a lunar eclipse last
Up to 1 hour and 45 minutes
What is a partial eclipse
The partial solar eclipse can be seen when moon moves into the disc of the sun but does not block it entirely
How many points of contact are there in a partial eclipse
2
What is an annular eclipse
The appearance of a ‘ ring of fire’ when the moon is further away from earth so the smaller moon does not cover suns disc entirely
Where is the focus of the umbra during an annular eclipse
Above the earths surface
When does a lunar eclipse take place
When moon enters earths shadow
Why is a lunar eclipse longer than a solar eclipse
Because the earth is bigger than the moon meaning the moon has to travel further to get out of earths shadow
What phase does the moon need to be for a lunar eclipse
Full moon
Who was Eratosthenes
A Greek mathematician and was a librarian of Alexandria in Egypt
What did Eratosthenes work out
The circumference of earth
What did Eratosthenes learn about near the town of syene
He leant that just to the south the sun appears at the zenith on the summer solstice
By observing and measuring shadows on the same day in Alexandra he calculated what
That the sun was over 7.12 degrees from the zenith
How much is 7.12 degrees of circle in a fraction
1/50 th
What was the disrptance of the two cities
5000 stadia
What calculation did Eratosthenes make
Multiplied the distance by the angle
What other thing did Eratosthenes work out
The diameter of the earth
Who was Aristarchus
Greek astronomer who first proposed that the earth orbited the sun
What allowed Aristarchus to determine that the earth was twice the size of moon
A lunar eclipse allowed him to study the shadow of earth over moon
He measured the width of both sun and moon and determined how many degrees of arc in width
2 degrees
How did Aristarchus try to understand the distances involved of the sun and moon from earth
He attempted to triangulate the moon sun and earth
What phase of the moon did Aristarchus use to measure the angle between moon and sun
Quarter phase
What was the angle that Aristarchus found from measuring the angle from the moon to sun during a quarter phase
87 degrees
How many times time further away, that Aristarchus calculated, was the sun than the moon
Between 18 and 20 times
How many degrees of arc are the moon and sun
1/2 degree
What is the actual angle sun of the sun and moon at a quarter phase
89.5 degrees
What was Aristarchus accurate in
In understanding that there was the same ratio between distance and size
What two monument help Eratosthenes calculate circumference of earth
Column at Alexandra
Well at syrene
