Transcript powerpoint - Physics @ IUPUI

Goal: To understand how the
sun works
Objectives:
1) Journey to the center of the sun!
Spaceship Sol
• Scheduled departure time: 5 min.
• Please fasten seatbelts.
What color is
The sun?
a) Yellow
b) Orange
c) Blue
d) White
e) Red
Spaceship Sol
• Scheduled departure time: 4 min.
• Prepare for departure.
Is the sun
a “star”?
a) Yes
b) No
Liftoff! Travel distance: 93 million miles
Heliosphere:
Solar Wind
speed: 390.0 km/s
density:
7 protons/cm3
Outside temp:
292K
68 F
Density outside:
Almost 0.
Outside temp:
400K
262 F
Density outside:
10 protons/cm3
Outside temp:
450K
352 F
Density outside:
28 protons/cm3
Outside temp:
604K
618 F
Distance to sun:
20 million miles
Density outside:
140 protons/cm3
Outer area of the
corona - the start
of the solar wind
Outside temp:
1208K
1705 F
Distance to sun:
5 million miles
Density outside:
2200 protons/cm3
Corona: millions of
degrees!
Outside temp:
2415K
3879 F
Distance to sun:
1.25 million miles
(0.8 million from the
surface)
Density outside:
35000 protons/cm3
Corona
Outside temp:
1 million K!
100k miles from
the surface
Chromosphere
Outside temp:
10000K
1k miles from the
surface
CORONAL MASS
EJECTION!!!
Rotation of the
sun.
The sun rotates
every 26-28
days,
depending on
where on the
sun you are.
Why could this be
important?
Photosphere
Outside temp:
5800K
Surface!
Density:
1% of air.
All of the sun’s
light that we
see comes
from here.
Question:
If we fly in onto
that sunspot,
will it be dark
or light?
Photosphere
Outside temp
5800K
Surface (400
km deep)!
Sunspots are
light!
They are 1-2k
cooler, so
compared to
the rest of the
sun, they
appear to be
darker.
Granules:
Convection
cells. Kind of
like in a pot
of boiling
water.
Welcome to the sun!
http://www.nasa.gov/mpg/118091main_other_loop_sm.mpg
Really cool flare video
• http://www.youtube
.com/watch?v=G7
Bj2qCDqEg&list=F
L8yB6Kof4yWtMsb
MAKgEjHQ&index
=25
Warning: breathing
apparatus will be
required as the sun is
made of 74%
Hydrogen, 25%
Helium, and only 1%
other stuff.
Question: where on or
in the sun is there a
solid surface to land
on?
How dense is the sun?
•
•
•
•
A) About the density of air
B) About the density of water
C) About the density of lead
D) more dense than any material on earth
How dense is the sun?
• B) About the density of water
• The average density of the sun is only
40% more than the density of water.
• Density of the sun is 1.4 g/cm3, vs. 1.0 for
water.
Convective zone:
Starts at the bottom of
the photosphere and
goes down for about
200k km.
Temperature:
6k on the top
2 million on the bottom!
Density gets up to
1/10th the density of
water.
Energy is transported
through convective
cells.
http://www.solarviews.
com/cap/misc/convect
3.htm
Radiative Zone
• Average density is water.
• This is a stable region, kind of like the Stratosphere on
the earth.
• Starts 200k km below the photosphere, and ends 200k
km above the center of the sun. That is 50% of the
radius of the sun!
• Energy is transferred by radiation.
• Temperature ranges from 2 to 7 million degrees Kelvin!
• How long do you think it takes light to pass through the
Radiative Zone?
Time for light to pass through the
Radiative Zone:
• Light will be scattered from 1 particle to
the next (sort of like light scattered by
water, but even worse, and imagine a pool
of water about 400k km deep!).
• Even though light travels at the speed of
light, it STILL takes 1 MILLION years for a
photon of light to get through this layer!
The Core!
• The core is the engine of the sun and is the
bottom 100-200k km of the sun.
• In the core, the force of gravity is pretty intense.
• Here there is a tug of war. Gravity is pulling
down, and gas pressure and radiative (light)
pressure is pushing up. The sun has to produce
lots of energy just to keep itself from collapsing
under its own weight! This is called Hydrostatic
Equilibrium.
• Temperature: up to 15 million degrees Kelvin!
• Density: up to 150 times the density of water!
Conclusion
• The sun is a wild, crazy, and often violent
place.
• It has weather that puts any weather the
earth has to same.
• Coronal mass ejections, if pointed right at
the earth, can do serious damage to
satellites, and possibly even our electric
grid!