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. Chromosphere 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.

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