the sun as seen by nasa w. dean pesnell nasa, goddard space flight center owens science center,...

The Sun as Seen by The Sun as Seen by NASANASA

W. Dean Pesnell

NASA, Goddard Space Flight Center

Owens Science Center, October 2009

(The Sun as seen by Miro.)

Why Study the Sun?Why Study the Sun?

Eddy, 1976, Science, 192, 1189

Wilma, October 2005

In 1976 Eddy noticed a Little Ice Age at the same time as low solar activity. Are the two related?Why was the Earth hot

for the dinosaurs?

Heat from the Sun creates hurricanes and thunderstorms


White LightWhite LightWhite light, which means no filters, can be used to study sunspots (or active regions) and eclipses.

This is one of the largest active regions ever recorded. The Earth is approximately the size of the blue dot.

From the SST on La Palma, the clearest, almost-true-color, picture of an active region.


Sunspots in 2001 by MDI on SoHOSunspots in 2001 by MDI on SoHO


Modern PhysicsModern Physics

The Sun is bright enough to take pictures in these lines. This shows us what each element is doing.

When you look closely you can see dark lines seen against the bright rainbow of sunlight. These lines led to modern physics and many things we use today (such as lasers and computers.)

HCa II Na


A Picture in HA Picture in HThe Sun in H on October 27, 2005. No sunspots were on the Sun.

Note the bright areas along the edges of the Sun. These are prominences just beyond that edge.

The dark line is a filament (prominence from the top.)

Photo by Greg Piepol, Rockville, MarylandOwens Science Center, October 2009

Here is a picture of a prominence on the limb of the the Sun using an H coronagraph in September 2005. The Earth is for scale.


Magnetic FieldsMagnetic FieldsA spectral line of iron at 630.2 nm can be used to measure the magnetic field of the Sun from the ground. These telescopes can’t see the Sun at night.

SDO will continually measure the magnetic field, allowing us to predict when the Sun will affect spacecraft and society.

Light areas are magnetic field directed toward us, darker pointing away from us.


Three Views of the SunThree Views of the Sun

Magnetic field, Ha, and Ca II K images from 1/19/2004. The large prominence in Ha is missing in the other two images.

Data of many forms is needed to understand the Sun. Owens Science Center, October 2009

Seeing Inside the SunSeeing Inside the SunHelioseismology uses sound to see into and through the Sun-like thunking a watermelon

The velocities under a sunspot show that material moves toward the spot near the surface and away from the spot lower down.

Right: Farside images show the active regions that launched the largest flares ever measured. We can see them on our side at top, continuing around the Sun in the middle and re-appearing at the bottom. The middle view is two weeks after the top and the bottom two weeks later.


Telescopes in SpaceTelescopes in Space

SOHO (NASA & ESA)

Yohkoh (NASA & JAXA)

SMM (NASA)

Owens Science Center, October 2009SORCE (NASA)

Stereo (NASA)


He I 304 Å from SOHO (50,000 K) TRACE loops (roughly 1 million K)

From space we can see light in UV and X-rays that is absorbed by the Earth’s atmosphere. The loops and swirls are created by material moving along magnetic fields.


““Seeing” Magnetic FieldsSeeing” Magnetic Fields

Data from the EIT on SOHO shows the complexity of the solar magnetic field. The changes from solar minimum (left) to near solar maximum (right) are also visible.


CMEsCMEs


LASCO Coronagraph on SoHO shows CMEs during the October 2003 storms


LASCO Coronagraph images showing 2 comets striking the Sun Owens Science Center, October 2009

Another set, showing Jupiter, Saturn, Mercury, and VenusOwens Science Center, October 2009

What You Can UseWhat You Can UseCoronado Personal Solar Telescope, H and Ca K, $500

Sunspotter Solar Telescope, $300

Baade Front Filter, $80

Coronado MaxScope 70,

$3000


What You Can DoWhat You Can DoData from the National Solar Observatory

Data from NASA satellites, SOHO, Trace, SDO (after launch), and others

Look for comets with SOHO

Study the Wilson effect

Look at light bridges

Watch for flares in H

Look at prominences

Count sunspots

Data can be freely used, but check each site for how to say thank you and how to confirm your Nobel prize winning discovery.


Sundogs are another thing to look for in the daytime sky. They are formed by ice crystals in the atmosphere.

This was seen in France on Sept. 20, 2005.



The Solar Dynamics Observatory, the first mission of Living With a Star, will provide the data needed to understand the solar convection zone and how magnetic field is assembled and dissipated in the solar atmosphere.

Thanks!Thanks!

SDO is at the Cape, ready to GO!(more tomorrow)

http://sdo.gsfc.nasa.gov

SummarySummary1. The Sun can be seen in many ways, and changes with time in

all of them.

2. The Sun’s magnetic field waxes and wanes with the solar cycle. As the Sun changes so does its ability to affect spacecraft and society.

3. You can observe the Sun yourself, with easily-purchased equipment, or use data from NASA and NSF telescopes.

4. SDO will measure the Sun’s light output and magnetic field, allowing us to predict when the Sun will affect spacecraft and society.



Three images taken in May 1998 by EIT on SOHO make up this false-color image. Images in Fe IX-X 171 Å (blue), Fe XII 195 Å (green) and Fe XV 284 Å (yellow) were combined into one that reveals solar features unique to each wavelength.

The magnetic structures in the corona are clearly traced in these images. Where and how those fields are created and destroyed is why we still study the Sun.


Telescopes on the Ground

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McMath Solar Telescope, Kitt Peak

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Come outside and see Mars at its closest approach!Owens Science Center, October 2009

Wanted, Day or Night: the Sun

Diameter: 1.4 million km (0.86 million miles, 110 Earth diameters)Mass: 2 1030 kg (2 nonillion kg, 330,000 times the Earth)Energy output: 4 1026 W (0.4 octillion W)Surface Temperature: 5770 K (10,420 ºF)Last Known Location: 150 million km (93 million miles) awayAKA: Old Sol, Die Sonne, Soleil, Sunce, Inti, Re, UTU, Helios

2004/07/09 Rz = 17

WARNING: The Sun is armed with very intense light. Approach with caution. Never look directly at the Sun without

protection.

Active Quiet

Vit

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tats

2004/07/20 Rz = 176

Active

SOH

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DI


Sunspot NumberSunspot Number

Drawings and photographs of the Sun can be combined to create the longest record of solar activity, the Sunspot number, which runs back to the 1600’s. The Maunder minimum corresponds to low sunspot number and low temperatures on the Earth.

Research continues into how solar activity affects the Earth’s climate.


Other ResourcesOther Resources• Sun-Earth Connection: http://sec.gsfc.nasa.gov

• Living With a Star: http://stargazers.gsfc.nasa.gov

• “Our Very Own Star: The Sun:” http://stargazers.gsfc.nasa.gov/epo/resources/Sun_booklet_English.htm

• Solar Dynamics Observatory: http://sdo.gsfc.nasa.gov

• Solar Heliospheric Observatory: http://soho.nascom.nasa.gov

• Today’s Space Weather: http://www.spaceweather.com

• Space Weather Data: http://sec.noaa.gov


Contact InformationContact Information

• W. Dean Pesnell: [email protected]


What Spectral Lines What Spectral Lines SaySay

• Presence composition

• Size temperature and brightness

• Location velocity

• Polarization magnetic field

Because it is bright, the Sun has played a major role in developing how to use spectral lines in physics. When 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.Owens Science Center, October 2009

the sun as seen by nasa w. dean pesnell nasa, goddard space flight center owens science center,...

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sorce nasa stereo nasa

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white light white light

magnetic fields

light areas

largest active regions