The Changing Sun
 

The Sun changes on many different timescales.

On geological timescales of billions of years, the Sun slowly brightens. Eventually, the Sun will expand and become a red giant, ungulfing Mercury, Venus, the Earth, and perhaps Mars. Five billion years from now, Pluto will be a balmy world with oceans 300 miles deep!
 
On human timescales of months to years, the Sun also changes. As in terrestrial storms, sunspots come and go over weeks to months. The average number of spots varies over a 22 year period known as the sunspot cycle. Several SSP scientists study these changes.
 
On shorter timescales of days, the Sun forms giant prominences and ejects pulses of material into the Solar System. These solar storms affect satellites orbiting the Earth and can disrupt telephone service, interfere with radio/TV broadcasts, and produce surges in the electric power grid. SSP scientists study these phenomena using satellites, including UVCS
 
Finally, the Sun pulsates. Leighton & Noyes discovered a 5 minute oscillation in the 1960's. Since then, astronomers have identified other oscillations with periods of minutes to hours. Several SSP scientists study the origin of these pulsations.

All of these variations teach us how the Sun works and how the changing Sun affects the Earth and other objects in the Solar System.

 
 

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