1. The Sun Our Star

2. The most important star for Earth is the one at the
centre of our solar system: the sun.
It provides the energy needed by plants and animals,
and it’s gravitational pull keeps the Earth in a steady orbit.
By studying the Sun, we also learn about other stars.
Since the sun is so close to Earth, it is the brightest object
in the sky. It is so bright, that you cannot see any other
stars while the sun is visible.

3. Our sun is mostly composed of hydrogen and helium.
The Sun and other stars produce huge amounts of heat and light energy through a process called nuclear fusion.
Under extremely high pressures and temperatures, two hydrogen nuclei combine to form a helium nucleus.
Our sun is mostly composed of hydrogen and helium.

4. Every second, the Sun makes more energy that people have used throughout history.
Scientists have calculated that the Sun has been producing energy for about 5 billion years and has only used up 25% of its available hydrogen. They also estimate that the Sun will continue to produce energy for at least another 5 billion years before it runs out of hydrogen.
The sun is about times larger than Earth

5. Lets study the Structure of the Sun

6. Structure of the Sun
Core
area with extremely high pressures
nuclear fusion takes place here
temperatures up to °C
Photosphere
The “surface” of the sun
Made up of churning gases (not solid)
“cool” region at only 6000°C
source of visible light for us on Earth

7. Structure of the Sun
Chromosphere
inner atmosphere
just above the photosphere
Corona
very hot, unstable and changing outer solar “atmosphere” at about °C
extends millions of km above chromosphere
visible during total solar eclipse

8. Eclipse is very dangerous to look at because
Eclipse is very dangerous to look at because (a) not as bright, so we don't
automatically look away, and
(b) there is still plenty of radiation from corona → damage and possible blindness in just a few seconds!

10. Features of the Sun
Sunspots
darker, cooler regions of the photosphere
can last from hours to weeks

11. Features of the Sun
Solar Flares
as sunspots age, nearby areas may violently erupt
they travel outward from the chromosphere through the corona
The sun releases huge amounts of energy outwards into the solar system, known as → solar wind
Earth’s magnetic field and components of our outer atmosphere help protect against the damaging effects of the energy and ions carried by the solar winds

12. Approximately every 11 years, scientists observe problems that occur with our radio and communication systems, and our electrical grids and distribution systems.
These problems have been linked with the occurrence of violent magnetic storms on the Sun’s surface.
These storms appear to occur when there are many sunspots present on the photosphere.

13. Solar Flare

14. If the ion streams are focused by the magnetic field and carried through Earth’s atmosphere, streams of colour are created known as Aurorae Borealis or the “Northern Lights”

15. Features of the Sun
Solar prominences
Large sheets of glowing gases bursting outward from the chromospheres
can flow straight out, or loop back into Sun
they can last for days or weeks and can grow as large as km high

16. Solar Prominence

17. Reading and Homework Time
□ Read/Scan pgs for a brief
overview of the Space Unit
□ Read pgs
□ Complete pg 308 #1-9
□ Read pgs
□ Complete pg 312 #1-5 and #7-9