OCR 21st Century Science P7 - Observing the Universe - Topic 2 - Mapping the heavens

An 11 slide powerpoint presentation on topic 2 of the OCR 21st century science P7 specification. It's as brief as humanly possible. Have fun! :D

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  • Created by: Aithne M
  • Created on: 15-04-11 21:27

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Slide 1

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f u n!
ha t
P7 ­ Observing the :P

Slide 2

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A few facts
The Sun appears to travel across the sky once every 24h (a
solar day)
The Moon moves slightly slower, reappearing every 24h 49m
The Moon's complete orbit around Earth occurs every 28
The stars appear to travel across the sky once every 23h
56m (a sidereal day)…read more

Slide 3

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Constellation: a group of stars that form a pattern in the sky
Some constellations seen on a winter night are different from
those on a summer night. This is because the Earth travels
half way around its orbit every six months. This means that
every six months, you see an opposite half of the sky
Each day, a particular star rises 4 minutes earlier. After six
months, those extra minutes add to 12 hours, so that a star
rising at dusk in June sets at dusk in December…read more

Slide 4

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Retrograde Motion
Against the background of stars, planets tend to move
steadily in one direction. However, at times they appear to
slow down and move in reverse. This is retrograde motion.…read more

Slide 5

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Solar eclipse: the Moon blocks the Sun's light
Lunar eclipse: the Moon moves into the Earth's shadow
Region of total darkness: umbra
Region of partial darkness: penumbra
If the Moon's umbra touches the surface of the Earth, a solar
eclipse is seen from inside the area of contact
If the Moon passes into the Earth's umbra, a lunar eclipse is
seen…read more

Slide 6

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Parsecs and parallax angles
A second of an arc is 1/3600 of a degree. This is a parsec.
A parsec is an object whose parallax angle is 1 second of an
An object whose parallax angle is 2 seconds of an arc is at a
distance of 0.5 parsec
One parsec is equal to about 31000000000000 km
:O If you
managed to take
that in on your
first read!…read more

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Slide 10

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This resource is really useful :)


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