Earth Sciences 1086F/G Lecture Notes - Lecture 4: Chromosphere, Photosphere, Astronomical Unit

• School: Western University
• Department: Earth Sciences
• Course: Earth Sciences 1086F/G
• Professor: Phil Mc Causland

Document Summary

Geocentric model - earth is at the centre of the solar system! Heliocentric model - sun is at the centre of the solar system! Perihelion - point of nearest approach of a planet to the sun! Photosphere - visible outer layer of a star! Sun"s atmosphere changes from being transparent to opaque over a few hundred kilometres! Size of the sun is usually meant as the region surrounded by the photosphere! Chromosphere - layer of gases surrounding photosphere (approx 2500km thick) invisible to eye! Chromosphere merges into outermost layer of sun, corona! Corona is only visible during a total solar eclipse! 1. 4 million km in diameter (109 times earth"s)! Sun contains approx 99. 8% of solar system mass! Rotation is oblately shaped (equatorial diameter > polar diameter)! 1 astronomical unit (au) is mean distance from earth to sun (150 million km)! The chemical composition of the sun is found using spectroscopy!