Lab 7
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Course
110L
Subject
Astronomy
Date
Dec 6, 2023
Type
Pages
6
Uploaded by AgentToadMaster997
1
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PHYS 110L Lab # 7
Observing Features on the Sun
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Equipment:
access to
http://helioviewer.ias.u-psud.fr
Instructions:
Please read and follow the steps described below and answer
all
questions.
Part #1 Exploring the Solar Dynamics Observatory (SDO)
In this section you will explore the space-based SDO solar observatory.
Step 1.
Read about SDO from the following links:
Two-Page Outline:
https://sdo.gsfc.nasa.gov/assets/docs/SDO_Brochure.pdf
Detailed 30-page guide (for those interested):
https://sdo.gsfc.nasa.gov/assets/docs/SDO_Guide.pdf
1
Modified from
Engaging in Astronomical Inquiry
, by S. J. Slater, T. F. Slater, and D. J. Lyons, 2010, W. H. Freeman
and Company. Also adapted from
GIC Hazard Prediction Helioviewer
,
https://gmd.mste.illinois.edu
.
Learning Objectives:
In this lab assignment you will conduct a series of inquiries about the nature and motion of
features on the Sun using solar images taken by space-based satellites.
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Step 2.
Watch part of the video showing 10 years of SDO observations of the Sun made at 17.1
nm wavelength (171 angstroms) available at:
https://svs.gsfc.nasa.gov/4776
Step 3.
Watch several videos of active regions and solar activity on the Sun found at the
following link:
https://sdo.gsfc.nasa.gov/gallery/ultrahd/
Part #2 The Helioviewer
The
Helioviewer
allows you to look at near real time images of the Sun taken by several space
telescopes in various light wavelengths.
Step 4.
Open your web browser and navigate to
http://helioviewer.ias.u-psud.fr/
. The image
displayed is the current image of the Sun taken within the hour. Take the short introductory
interactive tour of
Helioviewer
. You can access the tour by clicking the question mark in the
top-right corner and selecting Interactive Tutorial from the drop-down menu.
Step 5.
The current image of the Sun should be visible in the main viewing screen at the center.
You can zoom in or out on the image. To better see sunspots, change to a visible light by
locating the Images box on the left side of the viewer, set the Observatory option to SDO. Set the
Instrument to HMI and Measurement to continuum.
Question 1:
Are there any sunspots present? Be careful not to select active areas or non-sunspot
regions. Be aware that there are times when no sunspots are visible.
Yes, there are sunspots.
Part #3 Tracking Sunspots
Step 6.
In the Images box on the left, you can select different satellites and wavelengths for
viewing the Sun.
If you haven’t done so, b
egin with the latest images from the Solar Dynamics
Observatory (SDO). In the Images box on the left side of the viewer, set the Observatory option
to SDO. Set the Instrument to HMI and Measurement to continuum. At this setting, the Sun
looks very similar to what you would see in visible light.
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Step 7.
Like the Earth, the Sun rotates on its axis. By watching the movement of solar features,
like sunspots, on the Sun’s surface, astronomers have determined the length of one solar day
(Galileo did this in the early 1600’s). Using
Helioviewer
, you can make a movie of the Sun’s
surface, and use it to repeat the process of estimating the rotation period of the Sun. Select
Sunspots (near the bottom of the list) from the Features and Events menu. Try a start date for the
movie to be 14 days prior to doing the lab. Note: If there are no sunspots present, try setting the
date to 2014/06/20 in the Observation Date menu.
Step 8.
Click the Create a Helioviewer Movie
button in the top right corner and select
Full Viewport in the Generate a Movie menu. In the Movie Settings box, set the duration to 28
days, and click Ok to start processing your movie.
Step 9.
It may take several minutes to generate your movie (there is a processing update near the
upper-right corner). When the movie is done, click on the title of the movie in the Generate a
Movie menu and download and play the movie. If you have problems creating a movie, please
try using the alternative website:
https://helioviewer.org
or the beta site
https://beta.helioviewer.org
Question 2:
Do any of your sunspots make it around the Sun in your 28-day movie? (Note that
sometimes the movie is not quite 28 days in duration.)
Yes
How long did it take?
It took almost the whole time.
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How long is one day on the Sun? Remember, if you do not see any sunspots try changing the
observation date to 2014/06/20 and then generate the movie.
About 25 days
Part #4 Sunspot Cycle
Step 10.
Helioviewer
has images of the Sun dating back many years. Find the Jump setting in
the Observation Date menu and set the time interval to 1 year. Then use the left arrow to step
back time until 2010.
Question 3:
What changes do you see?
There’s one
big sunspot and not as many as in the present.
Step 11.
The Sun has 11-year sunspot cycles. In 2020-21, we are in a sunspot minimum. The
number of sunspots on the surface of the Sun peaked in 2012-2014. View data from these years
and compare it to today’s images of the Sun.
Question 4:
How do they compare?
2014 had a lot of sunspots, about 6-
7, and there’s only about 3 in
2023.
Part #5 Coronal Mass Ejection (CME)
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Step 12.
A coronal mass ejection is a giant cloud of solar plasma drenched with magnetic field
lines that are blown away from the Sun during strong, long-duration solar flares and filament
eruptions.
By constantly taking images of the Sun, space telescopes capture many of the Sun’s exciting
surface events. To view a CME, you need to add more image layers. Keep the Observatory set to
SDO and change the Instrument to AIA and set Measurements to 304. This image shows the Sun
in ultraviolet light.
Try zooming out if you can’t see a lot of features.
Step 13.
Add a second image layer by clicking on Add Layer, located to the right of Images. A
box for another telescope will open. For this new layer, set Observatory to SOHO (Solar and
Heliospheric Observatory telescope). Choose the Instrument to be LASCO, set the Detector to
C2, and the Measurement to white-light
. This will show an image of the Sun’s corona, the dim
outer layer of its atmosphere, by blocking out most of the Sun and its bright surrounding region.
Step 14.
Coronal mass ejections can happen up to three times a day and release as much energy
as 10 million volcanic eruptions on Earth. While this seems like a lot of energy, it is only about
10% as much energy as the Sun releases every second.
To view a coronal mass ejection, set the Observation Date to 2013/08/20 and the time (UTC) to
00:00:00. Set the Jump to 1 hour and advance the time by clicking the right arrow. You can also
select CMEs in the Features and Events menus to make spotting of CMEs easier. Describe what
you see.
Remember:
You are viewing coronal mass ejections and
not
sunspots.
Around the Sun I see a good amount of cloud things around the circumference. They don’t
extend too much, and there are spots where they look bigger than other spots.
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Conclusion.
Please provide feedback regarding the lab assignment. Are there things that you
liked or disliked? Thanks!!
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