Solar Surface

1. Solar Surface

2. Sun Facts • The Sun is a gas cloud of mostly hydrogen and helium. • The age is about 5 billion years. • Diameter: about 100 times Earth’s • Volume: about 1,000,000 times Earth’s • Mass : about 300,000 times Earth’s • Density = mass/volume = 1.4 g/cm3 • water is 1.0 g/cm3, Earth is 5.6 g/cm3

3. Luminous Gas • We only see the surface of the sun. • Not a solid surface • Temperature 5,800 K = 10,000 °F • Hot enough for visible light • Gases extend upward for thousands of km.

4. Solar Atmosphere • The Sun’s atmosphere is divided into three layers. • Different temperatures and densities chromosphere corona photosphere Sun’s interior

5. Eye on the Sun • The Solar Dynamics Observatory is in orbit around the Earth. • Launched Feb 2010

6. Photosphere • The visible surface is the photosphere. • Brightest part of the sun • The photosphere has features that show convection. Granules: Dark areas are cool and are sinking. Light areas are hot and are rising. Supergranules: Doppler color shows rising and sinking.

7. The chromosphere is immediately above the photosphere. Temperature to 20,000 K Faint compared to photoshpere Red from hydrogen gas The chromosphere is the site of prominences of hydrogen gas. Chromosphere

8. Corona • The outermost layer of the sun is the corona. • It can be easily seen during total eclipses. • It is as bright as the full moon. • The gas is thin but heated to over 1,000,000 K.

9. Solar Wind • This solar wind streams away from the sun at high speed (300 to 800 km/s). • The solar wind distorts planetary magnetic fields. • Measured beyond Neptune