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THE SUN: AWESOME AND ACTIVE

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Title: THE SUN: AWESOME AND ACTIVE


1
THE SUN AWESOME AND ACTIVE
  • Boston University PHOTON
  • Outreach Presentation

2
The Sun
  • An average-size yellow star, just like billions
    of others in the universe
  • Center of the solar system, Earth orbits around
    it
  • Formed about 4.6 billion years ago
  • The sun has a mass of 2x1030 kg or 330,000
    Earths, thats 99.8 of the mass in the solar
    system.

3
The Suns Energy Earth
  • The Sun is the source of all of the energy on
    Earth.
  • The amount of energy that reaches Earth from the
    Sun in one second is enough energy to meet
    Massachusetts current energy needs for
    32,655,294 years!!!
  • About half the energy that hits the Earth is
    absorbed and used to heat the planet.
  • You can feel this energy in the form of heat on
    your skin on a sunny day.

figure based on data from California Energy
Commision http//www.energy.ca.gov/electricity/us
_percapita_electricity_2003.html
4
Where does the Suns Energy Come From?
  • Energy is produced in the Suns core through a
    process known as nuclear fusion.
  • Nuclear fusion is when nuclei of one kind of
    element combine to make a new nucleus in that
    requires less energy to hold it together. This
    difference in energy is spit out as a result of
    the reaction.
  • The Suns nuclear fusion occurs when four
    hydrogen nuclei combine to make helium and
    release energy.
  • This type of reaction cant happen just
    anywhere, it can only happen at incredibly high
    temperatures and pressures like those found in
    stars, somewhere around 23 million degrees!!

Energy
1 Helium nucleus
4 Hydrogen nuclei
5
How much energy does the Sun make?
  • We know how much energy the Sun emits by
    measuring the amount of energy that reaches
    Earth.
  • The Sun consumes 660 million tons of hydrogen
    releasing 100 billion megatons of energy per
    second! Thats the same energy as 20 billion
    Hydrogen bombs every second!
  • Based on the amount of hydrogen the Sun consumes
    per second and the mass of the Sun, we estimate
    its lifetime to be 50 billion years.

Nuclear Fusion Hydrogen Bomb50 megatons
6
Whats inside the sun?
Layers of the Sun 1. Core the core of the sun
alone is the size of 13 Earths! 2. Radiative
Zone energy from the core radiates through this
part of the Sun 3. Convective Layer convection
cells move energy through this part of the
Sun 4. Photosphere This is the part of the sun we
see 5. Chromosphere a part of the Suns
atmosphere 6. Corona This is a bright halo
around the Sun
Diameter of the Sun Diameter of 56 Earths!
7
Energy Escapes the Sun
  • Fusion occurs in the Suns core, the hottest
    part.
  • The energy released by the fusion in the Suns
    core is in the form of light.
  • It only takes 8 minutes for light from the
    surface of the Sun to reach Earth
  • But it takes 170,000 for the light energy from
    the core to reach the Suns surface because it
    doesnt go in a straight line

8
The Changing Sun
  • The surface of the Sun is constantly changing
  • The Sun is shooting particles off it all the time
    called the Solar Wind
  • There is an 11-year Solar Cycle when the Sun
    goes from being very active (solar maximum) to
    not not very active (solar minimum

9
How is the Sun active?
  • The solar cycle is characterized by the rising
    and falling of solar activity
  • The solar maximum is the period of greatest solar
    activity
  • During solar maximum the Sun is more active
    meaning there are more sunspots and solar flares

10
Sunspots
  • What?
  • Dark spots on the Sun's surface that are cooler
    than the surrounding areas
  • Temperature of
  • Sunspot 3800 K
  • Surrounding area 5800 K
  • Why?
  • The strong magnetic field in that area stops the
    area from being able to transfer energy so the
    temperature isnt as high

11
More about Sunspots
  • Sunspots can be about the size of Earth or even
    bigger!!!
  • They come in pairs
  • They are still really hot, just not as hot as the
    rest of the Suns surface
  • Sunspots move across Suns surface as it rotates

12
Magnetic Activity on the Sun
  • Sunspots are caused by strong magnetic fields
  • Magnetic ropes break through the Suns surface
  • At each end of the rope is a sunspot
  • It is the Suns magnetic activity that causes
    solar storms and solar flares

13
How do we know all of this about the Sun?
  • Telescopes
  • You can look at the Sun through a telescope with
    special filters.
  • You can also use a solar telescope that projects
    the image of the Sun onto a piece of paper
    instead of into your eye.
  • Satellites
  • There are also several spacecraft that
  • are observing the Sun SOHO, TRACE, STEREO
  • These satellites look at the Sun in all
  • different kinds of light (ultraviolet, visible,
  • infrared, X-ray) to see everything that is
  • going on
  • Many cameras on telescopes need to use
  • a caronagraph, where a disk is used to block
  • out the Suns surface so we can see all the dim
  • stuff that the Suns brightness would drown out
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