The Sun - PowerPoint PPT Presentation

Loading...

PPT – The Sun PowerPoint presentation | free to download - id: 10f926-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

The Sun

Description:

NEVER LOOK DIRECTLY AT THE SUN. NEVER LOOK AT THE SUN WITH BINOCULARS OR A TELESCOPE ... During the Maunder Minimum in sunspot activity (1645-1715) it was very cold in ... – PowerPoint PPT presentation

Number of Views:10
Avg rating:3.0/5.0
Slides: 28
Provided by: LeeCa1
Category:
Tags: maunder | sun

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: The Sun


1
The Sun
  • Astronomy 311
  • Professor Lee Carkner
  • Lecture 23

2
Helios -- The God of the Sun
  • The Sun was often worshiped by ancient people

3
WARNING !
  • NEVER LOOK DIRECTLY AT THE SUN
  • NEVER LOOK AT THE SUN WITH BINOCULARS OR A
    TELESCOPE
  • PERMANENT EYE DAMAGE CAN RESULT

4
Observing the Sun
  • The solar surface is nearly featureless
  • Much of our information about the Sun comes from
    multiwavelength observations, indirect
    measurements, and modeling

5
The Sun From the Inside Out
  • The solar interior is the source of solar energy
    which is transported to the surface
  • Nuclear fusion and magnetic fields play key roles
    in the energetics and structure of the Sun

6
Why Does the Sun Shine?
  • From radioisotope dating we know that the solar
    system is 4.5 billion years old
  • Chemical energy (burning) --
  • Kelvin-Helmholtz contraction (gravitational
    energy) --
  • Nuclear Fusion Reactions --

7
The Core
  • At the core of the Sun the temperature and
    pressure are very high due to the weight of the
    outer layers
  • At these conditions the hydrogen atoms are moving
    so fast and are packed together so tightly that
    they can fuse together to make helium

8
Hydrogen Fusion
9
How Does the Energy at the Core Get Out?
  • Energy in the Sun is transported in two ways
  • Radiation --
  • Like a heat lamp
  • Gas in this area is very hot and ionized and so
    doesnt absorb the radiation very well
  • Convection --
  • Like baseboard heating
  • Cooler outer layers are less ionized and so
    absorb the radiation and heat up and rise

10
The Inner Structure of the Sun
11
The Photosphere
  • It takes about 170,000 years for the energy to
    reach the surface of the Sun
  • The visible surface of the Sun is called the
    photosphere
  • The photosphere is the top of the convection
    zone
  • Each about 1000 km across

12
Granules
13
Sunspots in the Photosphere
  • The photosphere sometimes has small dark regions
    called sunspots
  • Sunspots are regions where the Suns magnetic
    field inhibits the flow of warmer material

14
Sunspots
15
Sunspot Cycles
  • Sunspots exist for a maximum of a few months
  • There is a sunspot cycle of 11 years
  • Just after sunspot minimum the spots appear at
    about 30 degrees north or south

16
Sunspot Maximum and Minimum
17
The Sunspot Cycle
18
Sunspot Cycles and Differential Rotation
  • The Sun rotates differentially
  • The magnetic field gets wrapped-up around the
    equator
  • Eventually the magnetic field is squeezed so
    tight it reconnects and cancels itself out
  • The magnetic field prevents warmer material from
    flowing into the sunspots, so the sunspots are
    cooler than the rest of the photosphere

19
The Twisted Magnetic Field of the Sun
20
The Suns Magnetic Field
  • It is twisted and tangled producing loops of
    magnetic force
  • The Suns magnetic field is responsible for the
    structure and heating of the outer layers of the
    atmosphere

21
The Solar Wind
  • The magnetic fields in the outer layers of the
    Sun can accelerate material outward
  • Interacts with the Earths magnetic field
  • Very strong solar wind bursts can cause power and
    communication failures

22
The Chromosphere
  • The chromosphere is a diffuse layer of the solar
    atmosphere extending from the photosphere to
    about 2000 km
  • It has a temperature of about 20000 K
  • It is too thin for the atoms to collide and lose
    energy

23
The Corona
  • The corona is the outer layer of the Suns
    atmosphere
  • It is thinner and hotter than the chromosphere
  • This plasma emits strongly at ultraviolet and
    X-ray wavelengths

24
Flares and Magnetic Activity
  • The material in the corona is constantly changing
  • They are both examples of magnetic activity
  • During the Maunder Minimum in sunspot activity
    (1645-1715) it was very cold in Europe (The
    Little Ice Age)

25
Structure of the Sun
Core Radiative Zone Convective Zone Photosphere Ch
romosphere Corona
26
Summary Structure of the Sun
  • Core
  • fusion converts H to He and power the Sun
  • Radiative Layer
  • transports energy from the core
  • Convective Layer
  • transports energy to the photosphere
  • Photosphere
  • visible surface of the Sun
  • Chromosphere
  • hot middle atmospheric layer
  • Corona
  • very hot outer layer

27
Summary Solar Energetics
  • Thermonuclear Fusion
  • Energy is produced at the core of the Sun by
    converting hydrogen to helium
  • Energy Transport
  • Energy is transported via radiation where the
    opacity is low and via convection where the
    opacity is high
  • Magnetic Fields
  • The outer layers of the Sun are composed of hot
    plasma in magnetic loops
About PowerShow.com