The Sun is not a static body, but very active.The Sun is not a static body, but very active. Solar activity can have dramatic effects on the EarthSolar activity can have dramatic effects on the Earth Our Sun: Our Turbulent Active Star

Understand how the Sun affects the Earth and the solar system Understand how stars work Understand more about the laws of nature The Sun is the only star known to grow vegetables. (Dr.Philip Scherrer, Stanford University) SOHO SDO Why Study the Sun? STEREO

Ask Students: “How does the Sun Change?” Answers (selected answers from and 8th grade classroom) –Changes height in the sky –Changes in intensity –Changes in temperature –Changes distance from the Earth Many of these are “changes” of the Earth Students consider the Sun itself to be pretty constant. –Not a bad assumption but certainly not correct –Solar Constant: W/m2

What makes the Sun hot? Fusion in the Sun’s core produces heat/energy 6 protons -> He + 2 protons + 2 electrons + 2 neutrinos + energy

The Sun’s Roiling Surface Like fudge or oatmeal cooking, the Sun’s surface boils up with heat, then crashes down Size of Earth, for comparison

As the Sun turns Like the Earth, the Sun rotates. However, unlike the Earth, the Sun has a complex rotation mechanism. Approximately 5 months worth of images from 2001

Sunspots denote regions of strong magnetic fields. They appear dark because they are relatively cooler than the surface. Sunspots

What color is the Sun? 1

The Sun appears white to us but it radiates in all wavelengths (visible and nonvisible “colors”) The electromagnetic spectrum

The Sun in Another Light Extreme Ultraviolet image of the Sun at 195 Angstroms Visible Light has wavelengths between 4000 and 7000 Angstroms

Plasma emission traces out magnetic fields in the solar corona Seeing Magnetic Field lines

Solar prominence dwarfs Earth in size Huge flare of 28 October 2003 Common during the Sun’s active periods Solar Eruptions

The 11 year sunspot cycle A regular cycle of sunspot numbers over the past 300 years. The amount of magnetic activity on the Sun varies in an 11 year cycle.

Dramatic changes occur during the solar cycle X-ray and magnetic activity compared

Explosions on the Sun (Coronal Mass Ejections) A billion tons of hot gas being launched from the Sun. White circle in image indicates size and location of Sun, which is blocked by a metal disk in the instrument. Coronagraphs- Artificial Eclipses

A solar “wind” streams into the solar system and shapes Earth’s magnetosphere

The Sun generates Space Weather in our solar system Solar activity can have a dramatic impact on communications, satellites, and astronauts.

Solar activity causes colorful aurorae

Space Weather affects the Moon and other planets we hope to explore. Mars Aurorae on Neptune, Saturn, and Jupiter

Solar and Space Weather Links on the Web NASA Link –SOHO: –SDO: –STEREO: Stanford Solar-Center: –SID home page: CISM Home Page: Windows to the Universe: Exploritorium: SWPC: