NATS 1580 Lecture Notes - Lecture 5: Seismic Wave, Quiet Sun, Photosphere

• School: York University
• Department: Natural Science
• Course: NATS 1580
• Professor: Jagruti Pathak

Document Summary

~ nats 1580 sun, space weather and life on earth ~ The visible surface of the sun is called the photosphere. Opaque to visible light, and thus we see a sharp edge. The sun takes approx. a month to make a complete rotation. The equator rotates faster than the poles, with an equatorial rotation rate of about 25 days, while the poles rotate every 36 days. The average rotation rate of most importance to earth is about 27 days. High resolution images of the photosphere show that the sun"s visible surface is highly mottled, with dark and light regions called granules. Granulation is direct evidence of solar convection. Bright areas show a doppler blue shift indicating upward motion. Dark areas show a red shift indicating motion down into the solar interior. The granulation resulting from the convection covers the photosphere. The life time of a granule is 18 minutes.