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 Ancient people intertwined their fates with the motions of the Sun and planets Why was the Earth hot for the dinosaurs? Heat from the Sun creates hurricanes and thunderstorms Katrina, August 2006

Why Study the Sun? Wilma, October 2005 Ancient people intertwined their fates with the motions of the Sun and planets Why was the Earth hot for the dinosaurs? Heat from the Sun creates hurricanes and thunderstorms Katrina, August 2006 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. The Initiations of Orpheus, VII: To The Sun ca. 550 B.C.

Space Weather and Climate! 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 We look at the Sun at one frequency of light (like tuning a radio or when designing a neon sign.) FM100.7 MHz

Modern Solar Viewing Dialing in on a frequency is used to reduce interference in wireless connections FM100.7 MHz

Modern Solar Viewing FM100.7 MHz We see these frequencies as the colors of the rainbow. Pictures in these colors tells the story of the Sun. HH Ca IINa

Modern Solar Viewing FM100.7 MHz We see these frequencies as the colors of the rainbow. Pictures in these colors tells the story of the Sun. HH Ca IINa

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

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Scientists are often accused of using false colors. They are coded colors! (And funky stop-action movies.)

What You Can Use Coronado Personal Solar Telescope, , Ca K, $500 Sunspotter Solar Telescope, $300 Baade Front Filter, $80 Coronado MaxScope 70, $3000

What You Can Do Data from the National Solar Observatory Use data from NASA satellites, SOHO, Trace, SDO, and others Look for comets with SOHO and STEREO 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 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 Incandescent Bulb (White Light) with elements like Hydrogen and Helium 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

Fraunhofer Lines These are dark lines seen against the bright rainbow of sunlight. They were discovered 200 years ago.

The Sun is bright enough to take pictures in these lines. Each dark line is the signature of an element or molecule. We will look at the individual lines today. Hydrogen (H  ) Sodium Calcium Several elements Hydrogen (H  ) Iron O 2 (atm.) Fraunhofer Lines

A Picture in H  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, 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   A Picture in H Here is the Sun in H  on May 11, Photo by Kanzelhoehe Observatory, Austria H  images are taken at many sites each day.

Another solar spectrum HMI 6371 H  4340 Na 5890 H  4861 H  6583 Courtesy of N. A. Sharp, NOAO/NSO/Kitt Peak FTS/AURA/NSF.

What Spectral Lines Tell Us Presence  composition Size  temperature and brightness Location  velocity Polarization  magnetic field However a spectral line is measured, each piece of information tells us something. 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 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. Looks at hot source thru cool gas, sees absorption lines on 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, It will be accessible to everyone in the continental USA. Posters and information at

Web Resources Helioviewer ( 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: Solar Science Fair : Helioviewer : Solar Heliospheric Observatory: Today’s Space Weather: Space Weather Data: Sun-Earth Connection: Living With a Star:

Contact Information W. Dean Pesnell:

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 The Earth is for scale.

Web Resources