The Sun - PowerPoint PPT Presentation

Loading...

PPT – The Sun PowerPoint presentation | free to view - id: 1badc1-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:

The Sun – PowerPoint PPT presentation

Number of Views:20
Avg rating:3.0/5.0
Slides: 61
Provided by: Michelle7
Category:
Tags: sun | tocs

less

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

Title: The Sun


1
The Sun
  • LASSO Summer 2007 Workshop

2
http//stereo.gsfc.nasa.gov/classroom/classroom.sh
tml
3
  • The Sun
  • Largest object in the solar system
  • 99.8 of the total mass
  • Jupiter contains most of the rest
  • Radius is about 700,000 km
  • 100 times the radius of the Earth
  • Would take more than 1,000,000 Earths to fill
    it
  • 75 H, 25 He by mass (92.1 H, 7.8 He by number
    of atoms). The remaining 0.1 contains all of
    the other elements
  • About 4.5 billion years old, 5 billion years of
    life left

4
  • Masses of Things
  • 2x1030 kg Sun
  • 2x1027 kg Jupiter
  • 6x1024 kg Earth
  • 7x1022 kg Earths moon
  • 1x108 kg Nimitz class Aircraft Carrier
  • 2x106 kg Space Shuttle
  • 2x103 kg Toyota Camry
  • 4 kg newborn human
  • The sun and moon look about the same size, but
    they are not!

5
The Sun is the Heart of the Solar System
X-ray image of the sun from Yohkoh
6
  • The Sun
  • The sun rotates
  • 26 day period at the equator, slower above and
    below!
  • The suns equator tilted 7? from Earths orbital
    plane.
  • Distance to Earth 150,000,000 km
  • Light takes 8 minutes to reach Earth
  • Magnetic field in a sunspot 3000 gauss
  • Compare Earth 0.25 gauss

7
  • Why study the Sun?
  • All life on Earth depends on the Sun (Almost)
  • The Earth is warming up under the influence of
    human activity. How would the global climate
    vary, if only influenced by solar variability?
  • Not only are dynamic changes of the sun
    fascinating, but also they affects human
    activities
  • Disrupt communication satellites
  • Produce radiation hazards to astronauts
  • Power outages, particularly at higher latitudes
  • The Sun is the only nearby star, and so provides
    the only opportunity to directly study stars.

8
Parts of the Sun Interior Core source of
energy (fusion) T 15,000,000 K Radiation
Zone energy travels outward by radiation T
5,000,000 K Convection Zone energy travels
outward by convection T 2,000,000
K Atmosphere Photosphere visible surface of
Sun T 6000 K Chromosphere hydrogen emits
red light T increases to 20,000 K Corona
Extends out far into space (solar wind) T
2,000,000 K
9
(No Transcript)
10
Temperature of the Sun
11
  • 15 million degrees makes the core an unusual
    place
  • Here on terrestrial Earth and upper atmosphere we
    more commonly encounter hydrogen and helium in
    lower energy states
  • H2 (2 protons) or H (1 proton) w/o the extra
    neutrons
  • 4He (2 protons 2 neutrons)
  • Uncommon
  • 3He (2 protons 1 neutron)
  • D (1 proton 1 neutron)

12
The Core Fusion
13
(No Transcript)
14
Radiative Zone
15
The Photosphere The Visible Surface
Granules - convection cells
16
The ChromosphereThe Happening Place on the Sun
Prominence
Filament
17
The Grand Daddy Prominence
18
The Corona Gateway to Interplanetary Space
In white light
In x-rays
19
Solar Output
Visible, IR, and UV Radiation
Radio Waves
Solar wind plasma
Neutrinos
High-Energy Charged Particles
X-ray and gamma-rays
20
  • The Sun has a magnetic field
  • Magnetic fields create arches, arcades, loops in
    the corona. These are visible in X-rays and UV
    because they trap hot plasma.
  • Field structure
  • Dipole-like near the equator coronal helmet
    streamers
  • Open field lines near the poles coronal holes
  • Field extends out into space with the corona,
    carried by solar wind
  • The field changes polarity with an 11-year cycle
  • Changes thought to be due to differential
    rotation of the Sun (poles rotate faster than
    equator)
  • Variation with solar cycle
  • Near solar minimum field most dipolar, dipole
    aligned with rotation axis
  • Pre-minimum dipole is tilted relative to the
    rotation axis
  • Near solar maximum field is less dipolar

21
Emergent Magnetic Fields
Earth to scale
22
Coronal StructureSolar Maximum vs. Solar Minimum
Polar Coronal Hole
23
The Sun is variable in space and time 11-year
solar cycle Magnetic north and south poles
flip Solar minimum -- poles stable, little solar
activity Solar maximum -- field in transition,
lot of activity Sunspots Cooler (darker)
regions of the photosphere (4000 K) Strong
magnetic field (x1000) emerging from Sun Seen in
two zones, on either side of the equator Coronal
Mass Ejections (CMES) Ejection of large amounts
of mass (1015 g) Responsible for most large
geomagnetic disturbances Can last several
days Flares Explosions on surface of the
Sun Release electromagnetic and particle
energy Last from minutes to hours
24
Sunspot image from SOHO
25
Solar Variability The Sunspot Cycle
11 years
26
(No Transcript)
27
(No Transcript)
28
Solar cycle butterfly diagram of sunspot
occurrence
solar latitude
29
(No Transcript)
30
Solar Variability The X-Ray Sun
Solar Minimum (1995)
Solar Maximum (1991)
31
(No Transcript)
32
The Sun-Climate Connection? (Did Sunspots Sink
the Titanic?)
  • Sunspot correlated with
  • Sea surface temperature
  • Minimum latitude of icebergs

33
Coronal StructureSolar Maximum vs. Solar Minimum
Polar Coronal Hole
34
The Key to the Suns Activity Magnetic Fields
Convection
Active Region
Flux tubes rise through surface
Field carried to surface
Field generation
35
Magnetic flux emergence
36
Emergent Magnetic Fields
Earth to scale
37
Sunspots
38
Sunspots
39
http//stereo.gsfc.nasa.gov/classroom/matching/mat
ching_activity.shtml
40
MATCHING MAGNETIC ACTIVITY AND ACTIVE REGIONS The
solution is A - 3 B - 4 C - 5 D - 2 E - 1
41
Filaments/Prominences
cooler plasma
42
Filaments/Prominences
43
Solar Flares
overlying arcade
filament
two-ribbon flare
post-flare loops
44
Magnetic Reconnection
45
Solar Flares
overlying arcade
filament
two-ribbon flare
post-flare loops
46
Solar Flare and Post-Flare X-ray Loops
47
Helmet Streamers
Underlying Prominence
Helmet Streamers
48
Coronal Mass Ejections (CMEs)Erupting Helmet
Streamers
49
Erupting Prominence
50
Coronal Holes
open field easy escape fast flows
closed field inhibited escape slow flows
cool (dark)
51
Evolution of coronal hole Extension to low
latitudes
52
Whats wrong with the sun? Is the new sunspot
cycle late?
July 1, 2008
53
  • We are forgetting how long a minimum can last.
    This is not another Maunder Minimum. (David
    Hathaway MSFC)
  • 1933 was considered unremarkable.

54
We live with a very dynamic star!
55
  • Outstanding Questions
  • What causes the solar cycle? Why does it
    disappear at times?
  • Why is the corona so hot? We know its tied to
    magnetic energy, but what are the exact
    mechanisms?
  • What accelerates the solar wind to speeds of up
    to 1000 km/s, or more?
  • Will we ever be able to predict when CMEs will
    erupt, and how powerful they will be?

56
BACKUP MATERIAL
57
Earth-Sun Distance varies from 146 million km to
152 million km
146 million km (91 million mi) 0.286 Viewed
from Earth
152 million km (94.5 million mi) 0.275 Viewed
from Earth
  • J

Astronomy Picture of the Day http//antwrp.gsfc.na
sa.gov/apod/astropix.html
58
Moon and Sun from Stereo B spacecraft
59
(No Transcript)
60
Convection Zone Where the Sun Boils
About PowerShow.com