1.4 Earth Sun Moon Intetactions Flashcards
How long is a lunar month?
29.5 days
Why is the moon visible
Because it reflect sunlight
Why is a lunar moth 2.2 days longer that the moons orbital period
The extra time is needed to bring the moon sun and earth in alignment so the phases can start again
What is the correlation between the moon and sun that we have eclipsed
The sun is about 400 times fute her distant than the Moore and the sun is about 400 times larger in diameter so the angular size of the sun and moon are almost exactly the same
What’s a total solar eclipse?
The moon must be new and its when the moon directly passes in front of the sun, it can obscure light from the photosphere and produce a dark shadow in the umbra. Solar prominences are also visibly, temperature drops, we can see Corona
What are Baileys Beads
Small bright spots of sunlight caused by the Suns Ray’s shining through valleys on the moon - only visible at the end or beginning of a total solar eclipse - when just one bead is visible it’s know as the diamond ring effect
Why don’t solar eclipses occur every month?
Becuase the plane of the moons orbit is tilted by 5 degrees to the plane of the earths orbit around the sun, this means at most new moons the moon is either above or below the sun in the sky
What is the umbra in a total solar eclipse
The total shadow, if this observer was in a place of umbra he would be looking at a total solar eclipse
What’s the penumbra of a solar eclipse?
A partial shadow, the observer may not be in line with sun and moon so only sees a partial solar eclipse
What’s a lunar eclipse?
Shen the earth casts a shadow on the full moon and prevents sunlight from reaching it, they don’t occur every month due to moons plane but occur more often sure to earths shadow being larger and the moon falling into this area is more possible
How long can a total lunar eclipse last for?
30mins to an hour
What happens to the moon in a total lunar eclipse
The moon appears red/copper as light from the sun passes through the atmosphere and around the waste of the earth and since most blue light I scatters the red light is left behind and refracted by the earths atmosphere and illuminates the moon
What other shadow can be seen in a partial lunar eclipse
The curves shade of the earth
What are the 3 types of eclipse
Total - when it’s completely covered/ shadowed depending on which type of eclipse
Partial- when is partially covered or shadowed
Annular - when there’s a ring left around the luminous object being covered
Which way does the earth spin?
West to east
Which direction does the sun rise and set
Rises in east sets in west
What’s a sidereal day?
23hr 56min and is the time taken for a star to cross over the observers meridian and reach the same point the following day - 360 degree spin
What’s a solar day?
24h And its how long it takes for the SUN to go through the observers meridian and be there next day
its 4 mins longer due to the earth orbiting the sun at 1 degree every four minutes meaning we need an extra 4mins to allow the sun to return to the same position in the sky
According to a shadow stick when would solar noon be
When there is the smallest shadow as this is when the sun is highest in the sky
What’s apparent solar time?
It’s the physical sun - but it doesn’t move across the sun in a uniform manner due to our elliptical orbit and our polar axis being tilted - making time incorrect
What’s the mean solar time?
The time we set our clocks by, it’s imaginary and it’s done so we can pretend the sun is moving uniformly across the sky
What’s the equation of time? (Equation to fix apparent solar time)
EOT = apparent solar time - mean solar time (GMT)
Mean solar time = apparent solar time - EOT value
Apparent solar time =mean solar time + EOT value
How can you calculate longitude?
At apparent solar time on the Greenwich meridian, for every 4 minutes you are LATER of this time you are 1 degree west of Greenwich and for every 4 minutes EARLIER of that time you are 1 degree east
Why does the sun rise and set at different times during the year?
Earth’s tilt on its axis, the path of the Sun across the sky varies, and therefore, the rising and setting time changesThe reason for this is that the Earth’s axis is not perpendicular to its orbit: depending on the time of the year, either the northern or the southern hemisphere is tilted towards the Sun making the rising and setting times change
How is aurorae caused
By electrons from solar wind that have accelerated to high speeds in earth magnetic field, exciting atoms and molecules of oxygen and nitrogen in the upper atmosphere, as they de-excite or decelerate they emit light at certain wavelengths
What are the northern lights other know as
Aurora Borealis
What are the southern lights other known as
Aurora Australis
How long is a solar eclipse
7mins or less
