FORM 3 CHAPTER 9.1

1. STARS AND GALAXIES
CHAPTER 9.1

2. CHARACTERISTICS OF THE SUN
MASS: 1.98892 X 1030 KG
DIAMETER: 1,391,000 KILOMETERS
RADIUS: 695,500 KM
SURFACE GRAVITY OF THE SUN: 27.94 G
VOLUME OF THE SUN: 1.412 X 1018 KM3
DENSITY OF THE SUN: 1.622 X 105 KG/M
 LARGEST OBJECT IN THE SOLAR SYSTEM

3. FORMATION OF THE SUN
1. The sun was born about 4.6 billion years ago
2. Formed from a giant, rotating cloud of gas and
dust known as the solar nebula.
3. Nebula collapsed because of its gravity, it spun
faster and flattened into a disk.
4. Material was pulled toward the center to form
the sun.
5. Swell to become a red giant.
6. Eventually, it will shed its outer layers, and the
remaining core will collapse to become a white
dwarf.
7. Slowly, this will fade, to enter its final phase as a
dim, cool theoretical object sometimes known
as a black dwarf.

4. STRUCTURE OF THE SUN
CORE
CORONA
CHROMOSPHERE
PHOTOSPHERE
FLARE
SUNSPOT
PROMINENCE

6. THE PHOTOSPHERE
• The photosphere is the visible surface of the Sun.
• Is not a solid surface but is actually a layer about
300 km
• The temperature in the photosphere is about
6,000 degrees Celsius.
• One of the coolest layers of the Sun.
• Innermost atmospheric layer of dense gases.
• Considered as the surface of the Sun.

7. THE CHROMOSPHERE
• The chromosphere is 2000-3000 km thick
• It glows faintly relative to the photosphere
and can only be seen easily in a total solar
eclipse.
• When it can be seen it is reddish in colour
which is the origin of its name. (Chromos
means colour)
• Temperature rises from 6000°C to about
20,000°C

8. Phenomena on the sun’s surface and their
effects
A)SUNSPOT
• Appear as dark patches because cooler than
other parts of the surface.
• The dark patches are called the umbra.
• Sunspots often come in groups with as many as
100 in a group
• Gets more active on the sun every 11 years.
• Caused because its magnetically disturbed in the
sun.
• Can cause disturbance in the climate of the
earth.

9. B) PROMINENCES
• Also known as giant flames or even filament.
• An arc of gas that erupts from the surface of the Sun.
• Mostly seen in the photosphere.
• Can loop hundreds of thousands of miles into space.
• Held above the Sun's surface by strong magnetic fields and
can last for many months.
• Mostly helium and hydrogen are produced.
• Cause climate disturbance.
• The charged particles are called aurora.
• Aurore appears to be colourful in the polar region of the sky.

10. C) SOLAR FLARES
• Magnetic storm on the Sun which appears to be a
very bright spot and a gaseous surface eruption.
• Normally found in the photosphere.
• Release huge amounts of high-energy particles and
gases and are tremendously hot.
• Can reach up to 5 million degrees Celsius.
• Ejected thousands of miles from the surface of the
Sun.
• Causes violent explosion for few minutes in the Earth.
• This can also cause malfunction in the future birth.

11. GENERATION OF SOLAR ENERGY
• The sun’s energy comes from deep with its core.
• A process which is called as nuclear fusion takes
place.
• Hydrogen changes into helium, forming huge
amount of energy.
• This energy is then radiated out from the core
and moves across the solar system.
• The energy generated is carried to the sun’s
surface is released as heat and light.