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OCR 21 Century Science
Triple Science Physics Unit 7…read more

Slide 2

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What's In This Power point?
Looking into space
Astronomical Objects
The Lunar Cycle
Solar and Lunar Eclipses
A Solar Eclipse
Convex Lenses
Ray Diagrams
Using Parallax
Distance and Brightness
The Curtis-Shapley Debate
The Debate Continued
The Hubble Constant…read more

Slide 3

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Looking Into Space
The Earth rotates West to East every
24 hours.
The Stars around us appear to move East to West in 23
hours 56 minutes.
The time taken for planets, the moon and the Sun to pass
East to West across the sky is affected by their relevant
A Sidereal day is the time it takes for the Earth to rotate
360' on it's axis.
A solar day is the time from noon to noon, e.g. 24 hours
A sidereal day is 4 minutes shorter than a solar day.…read more

Slide 4

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Astronomical Objects
We can see different correlations of stars depending on
whether we are in the southern or northern hemisphere
and what time of year it is.
We can see stars because of the angle of declination and
ascension, is an astronomical object is declining we can
see it from the southern hemisphere whereas if a object
ascends we can see it in the northern hemisphere.
Planets look similar to stars
in the night sky however they
change in complex patterns
against the fixed pattern of
the stars.
Venus, Jupiter and the Moon…read more

Slide 5

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The Lunar Cycle
The lunar cycle is the Moon's appearance on Earth during it's 28
day orbit.
We can only see the moon because light from the Sun is
reflected from it, this is what gives us the different stages.
This means that we only ever see one side of the Moon and the
other side will never be seen from Earth.
The different phases of the
Moon are:
Dark face (new moon)
Light face (full moon)
Waxing or waning (all the points
between)…read more

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Solar and Lunar Eclipses
A solar eclipse occurs when the Moon passes
between the Earth and the Sun. This can occur
during a new moon.
Eclipses don't occur every month because the Moon
is at a 5' inclination to the Earth in it's orbit.
A total eclipse is when the Earth's view of the Sun is
totally obscured because of the Moon.
A lunar eclipse is when the Earth casts a shadow on
the Moon as it is between the Moon and Sun.
There are only 2 to 5 lunar eclipses a year.…read more

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Kiran Malhan


very helpful!
Thanks a lot :)

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