Notes

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Slide 1

Facts about the Sun & Sunspots Is 93 million miles from Earth Is about a million miles across Is just a huge ball of glowing gas – it’s not solid Is 5 billion years old, another 5 billion to go Is a medium-size star, one of about 2 billion in our galaxy Is covered with sunspots, which come and go At “Solar Max”, there are lots of spots Solar Max was about four years ago In two or three years, at “Solar Min”, there will be no spots!

Sunspots are BIG!

Sunspot history

Galileo’s drawings showed sunspots, & they moved! Galileo made a drawing each day, in the summer of 1612.  Try to do this yourself this summer! Here 36 drawings are put together into a “movie”.

How did Galileo know those spots were on the Sun?

Galileo used common sense to figure out that these dark spots were on the Sun, not planets or airplanes Study how the shapes of the spots change as they move from the center of the Sun’s disk to the edge

The Sun would look a lot different if your eyes could see X-rays! If your eyes could see X-rays, you would not see sunspots.  You would see the Sun’s corona.

What Galileo didn’t know: The Sun rotates faster near its Equator Equator: 25 days Pole: 35 days The Sun’s magnetic field gets all twisted up, and then it erupts

Scientists call these eruptions Coronal Mass Ejections (CMEs) A CME is a cloud of hot gas, weighing billions of tons, which erupts from the Sun at a speed up to millions of miles per hour. CMEs occur almost every day, but most go off in other directions, not toward Earth.

CMEs busting out all over This 16-day sequence during a very active period shows that CMEs happen often and they go in all directions.

S shapes in the X-ray corona CMEs often come from regions shaped like an S or reverse-S.  The S shown here erupted several times during the two days of the movie clip.

S marks the spot animation The S shapes store lots of energy.  A large CME releases about 100,000 times more energy than the world uses in a year.

How to recognize an Earth-bound CME

When CMEs hit Earth

Sometimes spacecraft get fried

Sometimes the power goes out

Sometimes beautiful auroras occur     Often called the northern lights, these sometimes colorful light shows in the night sky can sometimes be seen from here in Montana.

How can we prepare for CMEs? improve space weather monitoring & predictions conduct research on the Sun-Earth connection build stronger satellites and more protected systems take operational precautions in response to warnings

Web sites about Solar Max Sunspots and the Solar Cycle http://www.sunspotcycle.com • about sunspots, solar flares, and the latest news about the solar cycle. NOAA’s Space Environment Center http://www.sec.noaa.gov/Education/ • about current weather conditions in space near Earth, and more – the how and why of the effects of the Sun on Earth. Solar Storms and Their Human Impacts http://image.gsfc.nasa.gov/poetry/storms/storms.html • about effects of solar storms on satellites and power systems Max Millennium page at MSU - Bozeman http://solar.physics.montana.edu/max_millennium/press • a page of links to these and many other sites