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STARS
CHAPTER 29
BIG IDEA
• The life cycle of every star is determined by its mass,
luminosity, magnitude, temperature, and
composition
IN THIS CHAPTER
• 29.1 The Sun
• 29.2 Measuring the
Stars
• Link to Video
(24mins)
29.1 - THE SUN
• Main Idea:
• The Sun contains most of the mass of the solar system and has many
features typical of other stars
• The sun is more than 150 million Km from Earth but we still wear
sunscreen for protection because the sun’s rays are so powerful
PROPERTIES OF THE SUN
• The sun would take up
109 Earths, or almost 10
Jupiters, lined up edge
to edge
• The Sun is about 330,
000 times as massive as
Earth
• The Sun contains more
than 99% of all the
mass in the solar system
PROPERTIES OF THE SUN
• The Sun is dense! 13x than that of Lead
• A pair of dice acting like the centre would weigh
1kg
• The interior is made up of gas throughout because
of its high temperature
THE SUN’S ATMOSPHERE
• How does such a gaseous
planet have an atmosphere?
• The outer regions are
organized into different
levels, and each level emits
energy at wavelengths from
its temperature
• There are 3 layers we will be
learning about
• Photosphere
• Chromosphere
• Corona
PHOTOSPHERE
• It is the visible surface of
the Sun
• It is 400km thick and has
an average temperature
of 5527°C
• This is also the most
innermost layer!
• How?
• Because most of the
visible light emitted from
the Sun comes from this
layer
CHROMOSPHERE
• Outside the
photosphere is the
chromosphere
• It is approximately
2500km thick and
has a temperature
of 29 727°C
• Usually, the
chromosphere is
visible during a
solar eclipse when
the photosphere is
blocked.
CORONA
• The outermost layer of the Sun
• It extends several million 9,997,300,000°C
• This is where the radiation is emitted the most of UV
and X rays
SOLAR WIND
• The corona of the Sun
does not have an
abrupt edge, instead
gas flows outward at
high speeds
• This forms solar wind of
charged particles
• This wind flows at a
speed of 400km/h
AURORAS
• These charges particles collide with gases in Earth’s
atmosphere cause the gases to give off light called
Aurora
• These Auroras are often seen from Earth’s polar
regions.
• Also known as Northern Lights (aurora borealis)
• Link to Video
SOLAR ACTIVITY
• Other features on the Sun
change over time in a process
called solar activity
• There are fountains and loops
of glowing gas
• Caused by magnetic field
SUN SPOTS
• Dark spots on the surface of the photosphere
• They are bright but appear darker because they
are cooler
• They occur where the magnetic field is most present
SOLAR ACTIVITY CYCLE
• Every 11 years, the solar activity peaks because the
magnetic fields under go a rapid shift.
SOLAR FLARES
• Solar Flares are
violent eruptions of
particles and
radiation from the
surface of the Sun
• During the last Solar
flare in 2001, was
massive!
• It hurled particles
from the surface at
7.2 million km/h
• These small particles
bombard earth a
few days later. They
can be dangerous!
PROMINENCE
• Is an arc of gas
that is ejected
from the
chromosphere
• It then
condenses in
the inner
corona and
rains back to
the surface
SOLAR COMPOSITION
• The sun is made up of
• Hydrogen (70%)
• Helium (28%)
• And a small percent of the other elements
• Similar composition to that of the gas giants
http://www.youtube.com/watch?v=TO
Err4xntHE