Transcript THE SUN - 9dkipling

THE SUN
The Sun is a star = hot ball of plasma fuelled by
nuclear fusion at its core
Age: 4.6 billion years
The Formation of the Solar System
• Solar nebula theory: stars and planets form from
contracting, spinning disks of gas and dust
• Nebulas = a star nursery; a vast cloud of gas (hydrogen)
and dust;
Gas Pillars in the Eagle Nebula (M16): Pillars of Creation in a
Star-Forming Region
Crab nebula
The Formation of the Solar System
• Protostar: a hot condensed object in the centre of
a nebula
• Spinning nebulas contract and tiny fragments
collect forming rocky objects called planetesimals
Forming the Solar System
• Nebulas spin and flatten forming the plane around
the central star
• Planets and other objects revolve around the star
• Rocks that were not drawn into the Sun impacted
the planets and moon forming craters
Watch: https://www.youtube.com/watch?v=B1AXbpYndGc
How the Sun Formed
Gases compress in the nebula

temperature (10 million C)

Nuclear fusion (hydrogen nuclei combine to
form helium nuclei)

Core of star becomes protostar
Protostar’s core builds up, increasing temperature and
pressure
WHY HASN’T THE SUN EXPLODED ALREADY?
It’s a balancing act between:
• Pressure pushing outward by
nuclear fusion at the core and
• Gravity pulling matter inward
• Once balanced, a
stable star forms (like
our Sun)
• The Sun will grow to
become a red giant
4.60
billion
years
old
The Sun emits EMS (Electromagnetic spectrum)
Emits
Sun light = white light = combination of many
different colors (also wavelengths of light)
White light can be split
into a spectrum of colors
with a
diffraction prism
We see: ROYGBIV
Color
Wavelength (nm)
Red
520-750nm
Orange
590-620 nm
Yellow
570-590 nm
Green
495-570 nm
Blue
450-495 nm
Indigo
420- 450 nm
Violet
380 – 420 nm
Solar Dynamic Observatory (SDO)
Different features of the Sun can be revealed by viewing
it under different wavelengths
https://youtu.be/kS57VH3QN1g
Layers of the Sun
Corona
2 millionoC; 2100 km above photosphere
Chromosphere
Sits above photosphere
Photosphere
“Sphere of light”
Layer of Sun’s atmosphere; 6000oC
Sunspot
Areas of strong magnetic field located on the
photosphere; cooler than surrounding; 4500oC
Core
Nuclear fusion reaction occurs (H atoms fused into
He atoms); 15 mil. oC
Monitor the Sun live:http://www.helioviewer.org
The churning motion of the Sun's
convection zone creates magnetic
fields that
• float to the surface (photosphere)
and
• appear as darker (cooler) sunspots
How do scientists know what elements present inside the
Sun?
Different gases emit a unique pattern of light
absorption and emission when viewed through a
spectroscope  used as a fingerprint to identify
different element
Sun’s rotation
The Sun rotates faster at its equator
Inferences?
the Sun is not a solid body; it doesn’t have uniform
rotation
Sun’s Corona mass ejection (cme)
• Huge emission of energy and
charged particles
• So powerful that it shuts down
communications, power grids,
satellites on Earth
• Excitation of molecules/atoms
in Earth atmosphere creates
intense auroral displays.
Solar wind
Solar flare/storm
= an intense burst of
radiation coming from
the release of magnetic
energy associated with
sunspots.
a stream of fastmoving charged
particles ejected by
the Sun – creates
Auroras
Solar flares/ cme
Pros
- Can disrupt telecommunications - Gives beautiful aurora- Damage electronic equipment
fantastic light show
- Cause overload of power
network resulting in blackout
• Watch Secret of the Sun
Secret of the Sun https://www.youtube.com/watch?v=ncphh8FWUUE
Homework:
1. Read p333-340
2. Answer p336 #3,4; p338 #5-8; p340 #2-5,9