Slide 1

Facts about the Sun

is 93 million miles from Earth

sends its light to Earth in about 8 minutes

is made of 92% Hydrogen, 7% Helium, and 1% other gases

is 5 billion years old, another 5 billion to go

is a medium-size star, one of about 2 billion in our galaxy

has an 11-year cycle of solar activity

The Sun is big!

The Sun is almost a million miles across.

Names of things on the Sun

The Sun is the source of all our energy

Every second, millions of protons in the Sun's core collide with other protons due to powerful pressures to produce helium nuclei in a fusion reaction that releases energy.

The Sun’s energy comes from its core

The powerful fusion process that provides the Sun’s energy takes place in its core. Once generated, this energy passes out through the stable radiative zone (bright yellow) to the turbulent convection zone (gold).

You can see different parts of the Sun by looking in different colors

Different colors of light come from gases at different temperatures. The white light you see with your eye comes from the cool photosphere and sunspots; X-rays come from the hot corona.

The Sun’s rotation

The Sun rotates about every 27 days. Over a 10 day period, while Sun rotates, it reveals several regions of magnetic activity. Many changes take place – the Sun is far from constant.

The green color used here is false – it is simply added so scientists can easily know which wavelength was used.

Sunspots

Darker and cooler areas on the Sun are caused by strong magnetic fields. They last from several hours to several months. The number of spots you can see goes up and down with the rise and fall of the solar cycle (11 years).

Sunspots underlie coronal active regions

As we look at the Sun in various colors, we can see the relationship between features of the million-degree corona and those of the 6000-degree photosphere, such as sunspots, that underlie them.

The Sun’s magnetic field

The Sun is strongly affected by magnetic forces. The red arrows show the polar field lines of the Sun’s global magnetic field. The orange field lines show the magnetic field lines of the active regions. Each active region has its own pair of North and South polarities. The field lines joining them form the graceful arching loops seen in Yohkoh X-ray images.

Coronal Active Regions

This dramatic Yohkoh X-ray image of the Sun’s corona was taken in 1991, a few years after the last solar maximum. It was chosen by a poll of readers of Sky and Telescope magazine (January 2000) as one of the 10 most inspiring astronomical images of the century.

The Solar Cycle

The Sun follows an 11-year activity cycle. One indicator of solar activity is the number of sunspots. This chart shows that the Sun should approach its peak level or “solar maximum” around mid-2000.

Comparing the Sun: 1996 to 1999

By comparing images of the Sun over two years apart, you can see a dramatic difference in its activity levels. This increase is caused by the emergence of more and stronger magnetic fields. (Sun observed in extreme ultraviolet light.)

A Coronal Mass Ejection (CME)

A CME is a cloud of hot magnetized gas, weighing billions of tons, which is launched from the Sun at a speed up to millions of miles per hour. The CME shown in the sequence at the right was launched over an 8-hour period in 1996.

CMEs are caused by the breaking apart of magnetic forces. These occur almost every day, but most go off in other directions, not toward Earth.

Strong CME and proton blast

Near the end of this two-day movie, a solar flare occurs. The flare propels high-energy protons from the Sun to the spacecraft (92 million miles away) within just one hour. When the protons hit the spacecraft’s sensors, they cause a pattern of white specks, or “snow”

Solar flares from an active region

This movie captures the dynamics of a solar storm building up then blasting big solar flares twice over a 4-day period. Flares are intense and impulsive explosions on the Sun that propel high-energy protons into space.

CMEs busting out all over

This 16-day sequence during a very active period shows that CMEs occur often and in many directions..

How to recognize an Earth-bound CME

Sigmoids in the X-ray corona

CME’s tend to be launched from regions shaped like an S or reverse-S, called “Sigmoids. The sigmoid shown here erupted several times during the two days of the movie clip.

S marks the spot animation

The twisted magnetic fields of sigmoids store energy.

Space weather: a CME approaching Earth

It takes 2 to 4 days for a CME blast to reach Earth, as it expands up to 30 million miles wide. The white lines show the space filled by Earth’s magnetic field – the magnetosphere.

Earth’s Magnetosphere and a CME

Normal shape

Earth’s magnetosphere reacting to a CME

This supercomputer model was created by taking data from a number of instruments and developing a visualization of how the magnetosphere responded to a CME on Jan. 10, 1997. The clip shows a four hour period.

Auroras often occur when a CME hits Earth

Often called the northern or southern lights, these often colorful and flashing light displays in the night sky are mostly seen at high latitudes near the poles. They are caused by the impact of fast moving electrons from outer space (our magnetosphere) on the Earth's upper atmosphere.

Spectacular aurora

The auroral oval

Most locations can only see aurora when the solar wind is active due to solar storms. Then the Earth’s magnetic field directs energized particles into oval rings (see dotted line) near the poles that thicken and spread towards the equator.

CME impact on Earth’s magnetosphere

Seen on Earth as aurora, the impact of a CME on Earth’s magnetic field is captured in an ultraviolet video from the perspective of a spacecraft. The red areas indicate the most intense magnetic activity.

Aurora as seen from space

Powerful magnetic storm: 1989

In 1989, near the last solar maximum, a very strong solar storm impacted the Earth’s magnetosphere. Quebec, Canada lost power for 9 hours and power, navigational and communications systems around the world were upset. This computer model shows how the storm moved in just a few minutes. (Red means highest level).

When CMEs impact our magnetosphere

.

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

Many related Web sites can be explored

Windows to the Universe

http://www.windows.umich.edu/

• engaging Web-site that spans the Earth and Space sciences. Offers
classroom activities and resources.

NASA’s Education Program

http://www.hq.nasa.gov/education/

• introduces educators to NASA’s extensive resources available

NASA’s Space Image Libraries

http://www.okstate.edu/aesp/image.html

• a variety of sources for NASA’s space-related images

Views of the Solar System

http://www.hawastsoc.org/solar/homepage.htm

• an educational tour of the solar system, with images and information
about the Sun, planets, moons, asteroids, comets and meteoroids

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 Weather page

http://www.hq.nasa.gov/education/

• about current weather conditions in space near earth, including forecasts; a good site for learning about whether there might be an aurora tonight.

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

http://solar.physics.montana.edu/max_millennium/press

• a page of links to these and many other sites


	is 93 million miles from Earth
	sends its light to Earth in about 8 minutes
	is made of 92% Hydrogen, 7% Helium, and 1% other gases
	is 5 billion years old, another 5 billion to go
	is a medium-size star, one of about 2 billion in our galaxy
	has an 11-year cycle of solar activity


	Every second, millions of protons in the Sun's core collide with other protons due to powerful pressures to produce helium nuclei in a fusion reaction that releases energy.


	The powerful fusion process that provides the Sun’s energy takes place in its core. Once generated, this energy passes out through the stable radiative zone (bright yellow) to the turbulent convection zone (gold).


	Different colors of light come from gases at different temperatures. The white light you see with your eye comes from the cool photosphere and sunspots; X-rays come from the hot corona.


	The Sun rotates about every 27 days. Over a 10 day period, while Sun rotates, it reveals several regions of magnetic activity. Many changes take place – the Sun is far from constant.
	The green color used here is false – it is simply added so scientists can easily know which wavelength was used.


	Darker and cooler areas on the Sun are caused by strong magnetic fields. They last from several hours to several months. The number of spots you can see goes up and down with the rise and fall of the solar cycle (11 years).


	As we look at the Sun in various colors, we can see the relationship between features of the million-degree corona and those of the 6000-degree photosphere, such as sunspots, that underlie them.


	The Sun is strongly affected by magnetic forces. The red arrows show the polar field lines of the Sun’s global magnetic field. The orange field lines show the magnetic field lines of the active regions. Each active region has its own pair of North and South polarities. The field lines joining them form the graceful arching loops seen in Yohkoh X-ray images.


	This dramatic Yohkoh X-ray image of the Sun’s corona was taken in 1991, a few years after the last solar maximum. It was chosen by a poll of readers of Sky and Telescope magazine (January 2000) as one of the 10 most inspiring astronomical images of the century.


	The Sun follows an 11-year activity cycle. One indicator of solar activity is the number of sunspots. This chart shows that the Sun should approach its peak level or “solar maximum” around mid-2000.


	By comparing images of the Sun over two years apart, you can see a dramatic difference in its activity levels. This increase is caused by the emergence of more and stronger magnetic fields. (Sun observed in extreme ultraviolet light.)


	A CME is a cloud of hot magnetized gas, weighing billions of tons, which is launched from the Sun at a speed up to millions of miles per hour. The CME shown in the sequence at the right was launched over an 8-hour period in 1996.

	CMEs are caused by the breaking apart of magnetic forces. These occur almost every day, but most go off in other directions, not toward Earth.


	Near the end of this two-day movie, a solar flare occurs. The flare propels high-energy protons from the Sun to the spacecraft (92 million miles away) within just one hour. When the protons hit the spacecraft’s sensors, they cause a pattern of white specks, or “snow”


	This movie captures the dynamics of a solar storm building up then blasting big solar flares twice over a 4-day period. Flares are intense and impulsive explosions on the Sun that propel high-energy protons into space.


	This 16-day sequence during a very active period shows that CMEs occur often and in many directions..


	CME’s tend to be launched from regions shaped like an S or reverse-S, called “Sigmoids. The sigmoid shown here erupted several times during the two days of the movie clip.


	It takes 2 to 4 days for a CME blast to reach Earth, as it expands up to 30 million miles wide. The white lines show the space filled by Earth’s magnetic field – the magnetosphere.


	This supercomputer model was created by taking data from a number of instruments and developing a visualization of how the magnetosphere responded to a CME on Jan. 10, 1997. The clip shows a four hour period.


	Often called the northern or southern lights, these often colorful and flashing light displays in the night sky are mostly seen at high latitudes near the poles. They are caused by the impact of fast moving electrons from outer space (our magnetosphere) on the Earth's upper atmosphere.


	Most locations can only see aurora when the solar wind is active due to solar storms. Then the Earth’s magnetic field directs energized particles into oval rings (see dotted line) near the poles that thicken and spread towards the equator.


	Seen on Earth as aurora, the impact of a CME on Earth’s magnetic field is captured in an ultraviolet video from the perspective of a spacecraft. The red areas indicate the most intense magnetic activity.


	In 1989, near the last solar maximum, a very strong solar storm impacted the Earth’s magnetosphere. Quebec, Canada lost power for 9 hours and power, navigational and communications systems around the world were upset. This computer model shows how the storm moved in just a few minutes. (Red means highest level).


	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


	Windows to the Universe
	http://www.windows.umich.edu/
	• engaging Web-site that spans the Earth and Space sciences. Offers classroom activities and resources.

	NASA’s Education Program
	http://www.hq.nasa.gov/education/
	• introduces educators to NASA’s extensive resources available

	NASA’s Space Image Libraries
	http://www.okstate.edu/aesp/image.html
	• a variety of sources for NASA’s space-related images

	Views of the Solar System
	http://www.hawastsoc.org/solar/homepage.htm
	• an educational tour of the solar system, with images and information about the Sun, planets, moons, asteroids, comets and meteoroids


	Sunspots and the Solar Cycle
	http://www.sunspotcycle.com
	• about sunspots, solar flares, and the latest news about the solar cycle.

	NOAA’s Space Weather page
	http://www.hq.nasa.gov/education/
	• about current weather conditions in space near earth, including forecasts; a good site for learning about whether there might be an aurora tonight.

	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
	http://solar.physics.montana.edu/max_millennium/press
	• a page of links to these and many other sites