P7: Naked Eye Astronomy

jamiemcparlin
Mind Map by , created over 6 years ago

Physics (P7) Mind Map on P7: Naked Eye Astronomy, created by jamiemcparlin on 05/08/2013.

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jamiemcparlin
Created by jamiemcparlin over 6 years ago
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P7: Naked Eye Astronomy
1 The Earth Rotates on its axis
1.1 It does this West to East once in just under 24 hours
1.1.1 This causes the stars to appear to move East to West in the same amount of time
1.1.2 The sun, planets and moon also appear to move east to west across the sky, however the time they take to do this depends on their individual orbits
1.1.2.1 The sun appears to travel across the sky once every 24 hrs
1.2 A sidereal day is the time it takes for the earth to rotate 360 degrees on its axis
1.2.1
1.3 A solar day is the time from noon one day, to noon the next (i.e. 24 hrs)
1.3.1 The earth orbits the sun as well as rotating on its axis
1.3.1.1 It is this that makes the sidereal day 4 minutes shorter that a solar day
1.3.1.2 Different stars can be seen at different times of the year, depending on the position of the earth in the suns orbit
2 The Position of Astronomical Objects
2.1 The position of astronomical objects can be measured in terms of angles as seen from the earth.
2.1.1 Angles of "Declination" and "Right Ascension" describe the positions of stars in relation to a fixed point on the equator
2.1.1.1 Declination is measured south and north of the Equator
2.1.1.1.1 A star with Positive declination will be visible form the northern hemisphere
2.1.1.1.2 A star with Negative Declination will be visible from the southern hemisphere
2.1.1.2 Right ascension is measured around the celestial equator
2.2 Planets can be seen from earth with the naked eye, they look similar to stars but change their positions in a complicated pattern
2.2.1 When compared to backgrounds of fixed stars, planets appear ti move with a retrograde motion
2.2.1.1 This is because the earths smaller orbit causes it to overtake each of the outer planets at different times of the year.
2.2.1.1.1 This causes these planets to slow down against the star background and go into reverse
2.2.1.2 Retrograde motion- The apparent backwards motion of planets from west to east due to the combined motion of earth and the planets
3 The Moon
3.1 Whilst the Earth is rotating on its axis, the moon is orbiting the Earth in the same direction
3.1.1 Due to this, the moon appears to be moving East to West across the sky in a little over 24 hours, faster than the earth
3.2 The Lunar Cycle describes the moons appearance during its 28 day orbit
3.2.1 The moons shape during its orbit is due to the part of the moon that is visible to the earth
3.2.1.1 We are able to see the moon because of the suns light reflecting off it
3.2.1.1.1 The side facing away from the sun appears dark
3.2.1.1.2 The side facing towards the sun appears light
4 Eclipses
4.1 Solar Eclipse
4.1.1 This occurs when the moon passes between the earth and the sun
4.1.1.1 This results in the moon casting a shadow on the earth
4.1.2 Total Solar Eclipse
4.1.2.1 Occurs when the moon is directly in front of the sun and completely obscures the earths view of the sun
4.2 Lunar Eclipse
4.2.1 Occurs when the earth is between the sun and the moon
4.2.1.1 Results in the Earth casting a shadow on the moon
4.3 Lunar eclipses don't occur every month because the moon orbits the earth at a 5 degree angle to that of the earths orbit of the sun
4.3.1 An eclipse can only occur when the moon passes through the ecliptic ( the apparent path the sunlight traces out along the sky)
4.3.1.1 There are between 2 and 5 solar eclipses ever year
4.3.1.2 A total eclipse will only occur roughly ever 18 months

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