Earth Sciences 1086F/G Chapter Notes - Chapter 2: Main Sequence, Local Group, Orion Arm
7 Dec 2014
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Distance travelled by light in one year measure distances in space: light travels 9. 5 x 10^12 km/year. However, value too large: measure distances in terms of number of light years, ex: when looking at a star that is approx. 1 million light-years away, really looking at light that existed 1 million years ago looking back in time. Measuring light years: up to 500 light years distant, trigonometric parallax, determine distances to nearby stars, trigonometric parallax. Apparent change in an object"s position when viewed from two different vantage points, and the difference in angles between two lines of sight can determine the distance to the star. Must know distance between two view points and angle. 1 au = 150 million km = distance from earth to sun. 500 to 500 million might years distant: hertzprung-russell diagram. Brightness of stars: relating luminosity of stars to temperature (related to colour) Use calibrated colour chart determine exact colour to know temperature.
