Unit 2 Flashcards
Astrology
Belief that the star arrangement affects our everyday life.
Astronomy
The study of space
Constellations
Groups of stars developed by ancient Greeks
They don’t exist because stars are at different distances
Early practical uses of stars
- timelines were used depending on where the stars were in the sky
- caleneder depending on which stars appeared in the night sky
- directions like North Star
Geocentric theory
The earth was the centre of universe and everything revolves around us.
The stars were one single plane (same distance away)
Copernicus
Heliocentric theory.
Believed earth was not the centre but the sun was.
He had no proof to support his hypothesis.
Three key scientists who showed proof for heliocentric theory.
Kepler, Galileo, and Newton.
Kepler
Proved that objects in space must be at different distances.
Galileo
Improved the telescope and used it to first look at stars and planets
Newton
Proved that the sun has enough mass to hold objects in orbit.
Sun is the centre
Rotation
Turning of the earth on its own axis
Sidereal day
Rotation relative to stars in space is faster than 24 hours. ( 23 hrs 56 min)
Revolution
Movement of earth around the sun
Circumpolar constellations
- Constellations found more north and south
- appear to make circles in the night sky
Rising and setting constellations
Te constellations found along the suns path = zodiac constellations
-closer to equator
What do stars emit?
particle radiation and non particle radiation
Light travels at
300 000 km/s
Heliocentric theory
Earth was not centre but sun was
How many constellations
88
Revolution takes
365 1/4 days
How long does rotation take
Rotation takes 24 hours but a sidereal day takes 23 hrs 56 min
What causes seasons
When northern hemisphere is tilted towards the sun it is summer
When northern hemisphere is tilted away from sun it is winter
Spectroscope
Used to observe the properties of visible light.
Divides light into its component colours
Hubble telescope
- Launched in 1990
- Reflecting telescope
- Moves around earth approximately 100 minutes.
- No atmosphere so a clear image
- it costed a lot of money
Optical telescopes
Increase the size of the object we are looking at
Make objects appear brighter
Observe visible light
Disadvantages and advantages for refracting telescopes
They are not limited in size. The bigger the mirror the clearer the image
Can built very large so is expensive
