Transcript Franklin_Institute_May_2016x

The Sun: Astronomy for
People Who Sleep at Night
W. Dean Pesnell
SDO Project Scientist
Franklin Institute
May 2016
Why Study the Sun?
Wilma, October 2005
Katrina, August 2006
Heat from the Sun
creates hurricanes and
thunderstorms
Why was the Earth hot for
the dinosaurs?
Ancient people intertwined their fates with the motions of the Sun and planets
Why Study the Sun?
HEAR golden Titan, whose eternal eye
With broad survey, illumines all the sky.
Self-born, unwearied in diffusing light,
And to all eyes the mirror of delight:
Lord of the seasons, with thy fiery car
And leaping coursers, beaming light from far.
Wilma, October 2005
Katrina, August 2006
The Initiations of Orpheus, VII: To The Sun
ca. 550 B.C.
Heat from the Sun
creates hurricanes and
thunderstorms
Why was the Earth hot for
the dinosaurs?
Ancient people intertwined their fates with the motions of the Sun and planets
Space Weather and Climate!
Eddy, 1976, Science, 192, 1189
In 1976 Eddy noticed a Little Ice Age occurred at the same time as low solar
activity. Are the two related?
Space Weather and Climate!
But scientists still act
like children when we
see cool things in your
telescopes.
We Still Watch Transits
On May 9, 2016, Mercury passed between Earth and Sun – a transit.
Modern Solar Viewing
FM100.7
MHz
We look at the Sun at one frequency of light (like tuning a radio or when designing a neon sign.)
Modern Solar Viewing
FM100.7
MHz
Dialing in on a frequency is used to reduce interference in
wireless connections
Modern Solar Viewing
Ca II
FM100.7
MHz
Na
H
We see these frequencies as the colors of the rainbow.
Pictures in these colors tells the story of the Sun.
Modern Solar Viewing
Ca II
FM100.7
MHz
Na
H
We see these frequencies as the colors of the rainbow.
Pictures in these colors tells the story of the Sun.
Scientists are often
accused of using false
colors.
They are coded colors!
6000 K
4500 K
10,000 K
50,000 K
0.6 MK
1 MK
2 MK
2.5 MK
6 MK
10 MK
??????
Scientists are often
accused of using false
colors.
They are coded colors!
(And funky stop-action
movies.)
What You Can Use
Sunspotter Solar Telescope, $300
Baade Front Filter, $80
Coronado Personal Solar Telescope,
H, Ca K, $500
Coronado
MaxScope 70,
$3000
What You Can Do
Look for comets with SOHO and STEREO
Data from the National Solar Observatory
Watch for Comet ISON in SDO on Thanksgiving
Study the Wilson effect
Look at light bridges
Watch for flares in H or AIA
Look at prominences
Count sunspots
Travel the world and observe solar eclipses
Use data from NASA satellites, SOHO,
Trace, SDO, and others
Data can be freely used, but
check each site for how to say
thank you and how to confirm
your Nobel prize winning
discovery.
Where else can you use a rock
album to teach physics?
Colors and Spectrum
A spectrum is what we see
when light is sent through a
prism or grating. The colors
of the light go to different
locations.
Our ideas of color come from
the spectrum of reflected
light.
The rainbow comes from the
hot gas (measures T) and the
lines are the signatures of the
elements (measures what the
Sun is made of.)
The Solar Spectrum combines
Incandescent Bulb (White Light)
with elements like Hydrogen
and Helium
Fraunhofer Lines
These are dark lines seen against the bright rainbow of
sunlight. They were discovered 200 years ago.
Fraunhofer Lines
Each dark line is the signature of an element or molecule. We
will look at the individual lines today.
The Sun is bright enough to take pictures in these lines.
A Picture in H
By tuning a filter to the
right frequency, here is
the Sun in H during the
transit of Venus on June
8, 2004. This was the
first Venus transit
observed by high-grade
telescopes around world!
Note the bright areas
along the edges of the
Sun. These are
prominences just beyond
that edge.
Photo by Andrew Chapman, Victor, New York
H images are taken at many sites each day.
A Picture in H
Here is the Sun in H on
May 11, 2016.
Photo by Kanzelhoehe Observatory, Austria
H images are taken at many sites each day.
Another solar spectrum
H
6583
HMI
6371
Na
5890
Hb
4861
Hg
4340
Courtesy of N. A. Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF.
What Spectral Lines Tell Us
However a spectral line is measured, each piece of
information tells us something.
•
Presence  composition
•
Size  temperature and brightness
•
Location  velocity
•
Polarization  magnetic field
A copy of a plate from an article by G. E.
Hale in The Astrophysical Journal (49,
153, 1919). Shows how the magnetic field
of the sunspot make the line visibly thicker.
Looks at hot source thru cool gas,
sees absorption lines on continuous
spectrum.
Looks at cool gas lit by hot source, sees emission
line spectrum; Looks at hot gas that lets most light
through, sees emission line spectrum.
Looks at hot source, sees continuous spectrum.
Today We Will
• Look at several
sources through our
spectrographs
• Draw what we see
• Compare the sources
• Use phone cameras to
record a spectrum
Incandescent Bulb (White Light)
with elements like Hydrogen
and Helium
Sundogs are
another thing
to look for in
the daytime
sky. They are
formed by ice
crystals in the
atmosphere.
This one was
seen in France
on Sept. 20,
2005.
There will be a total eclipse
of the Sun on August 21,
2017. It will be accessible
to everyone in the
continental USA.
Posters and information at
http://greatamericaneclipse.com
Web Resources
• Helioviewer (http://helioviewer.org/) is an easy-to-use web-based application
to examine time series of solar images. Can overlay images from SOHO &
SDO and stream large data sets interactively in real-time. Allows zoom, pan,
basic image processing and overlay of events from catalogs.
Web Resources
• Solar Dynamics Observatory: http://sdo.gsfc.nasa.gov
• Solar Science Fair: http://solarsciencefair.org
• Helioviewer: http://helioviewer.org/
• Solar Heliospheric Observatory: http://soho.nascom.nasa.gov
• Today’s Space Weather: http://www.spaceweather.com
• Space Weather Data: http://swpc.noaa.gov
• Sun-Earth Connection: http://sec.gsfc.nasa.gov
• Living With a Star: http://stargazers.gsfc.nasa.gov
Contact Information
• W. Dean Pesnell: [email protected]
Questions?
How do we know what’s
happening at the
center of the Sun?
Here is a picture of a prominence on the limb of the the Sun using
a H coronagraph in September 2005. The Earth is for scale.
Web Resources
Web Resources