physics P1 (6)
- Created by: haidee
- Created on: 02-05-12 19:45
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The scale of the universe
- Moon has a 3500km diameter
- Earth has a 12500km diameter
- Solar system has a 12 billion km diameter
- Milky way galaxy has a 100000light years diameter
- Universe has a 59 billion light years diameter
- Astronomical distances are so huge that measurements of distance in kilometres are exceedingly large
- So the unit of distance used is the light year which is the distance travelled by light in one year
- Light travels at 300 000 000 m/s
- One light year = 9 460 000 000 000 000m
Red and blue shifts
- Light from moving objects will appear to have different wavelengths depending on the relative motion of the source and the observer
- Observers looking at an object that is moving away from them see light that has a longer wavelength that it had when it was emitted (a red shift), while observers looking at an approaching source see light that is shifted to shorter wavelength (a blue shift)
- By measuring the amount of shift to the red, we can determine the rate at which objects…
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