Project2_Module7
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School
University of Florida *
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Course
1002
Subject
Astronomy
Date
Apr 3, 2024
Type
docx
Pages
4
Uploaded by CommodoreWhaleMaster168
Felicia Wilks
Project #2: Charting Sunspots
PLEASE NOTE: All projects must be submitted in PDF format (not .docx or .pages).
The Sun has spots! They were first observed by Galileo, and we understand them today as the result of
intense magnetic "activity" on the Sun's surface (see Chapter 11 in your text). The spots are darker than
the rest of the solar "surface" because the strong magnetic field running through the spots inhibits the
convection (up-welling) of hot gas from below. Thus, the gas in the spots is cooler and darker than the
surroundings. Above the spots (higher up in the Sun's atmosphere) is very hot gas, which is often
involved in coronal "loops" and "flares."
NASA has a satellite called SOHO (SOlar and Heliospheric Observatory) that takes daily pictures of
the Sun. Here are some images from Oct 21
st
, 2013:
The middle image above shows a few dark spots in visible light. The first image (taken at about the
same time) shows extreme hot gas measured in far-UV light. Notice that the hot spots seen in UV light
lie directly above the cool dark sunspots seen in the visible. The third image shows the strength of the
magnetic field in the solar photosphere, with black and white indicating polarity. You can see how the
sunspots align with the north and south polarities in the magnetic field. This is the reason why sunspots
always appear to be in pairs.
The Assignment:
Estimate the rotation period of the Sun based on the movement of the spots. Procedure:
1.
Log onto the SOHO web site
2.
Go to the sunspot archive to download images of the Sun: https://sohowww.nascom.nasa.gov/data/synoptic/sunspots_earth/
There are images of the Sun in the archive since 2006. The Sun doesn’t always have sunspots, but we are currently in a period of major sunspot activity. From the images after July 1, 2023,
select a sunspot to follow.
Felicia Wilks
3.
You need to review images of different days until you find a large, clearly visible, sunspot like
the one in the image above labeled 1877, the one with the red arrow. (The spot should be on the
left side of the Sun in the first image you select because the spots will move from left to right
and you will need to track it.) 4.
Once you identify a "good" sunspot to follow, select 10 consecutive days to download images.
These images should be included with your project. Each time, record the date listed for the
image, the sunspot numbers and locations as described below. While you're there, click on "The
Sun Now" icon to see images of coronal loops and active regions concentrated above the
Sunspots. If you click around even more, you'll find movies and other cool stuff.
5.
For your first "observation," the one with the sunspot closest to the left rim of the Sun, record
the date listed for the image, the sunspot number and mark its location on the image below:
This grid marks every 10 degrees of longitude (and latitude), with 0 degrees longitude corresponding to
the bold vertical line down the center.
6.
Record the position of the sunspot every other day on the same grid. For example
, if your first
image was from August 21
st
, 2023, you will record the position of the sunspot on August 21
st
,
Felicia Wilks
23
rd
, 25
th
, 27
th
, 29
th
and 31
st
. That will give you 10 days of observations. (
You are welcome to
record the position every day if you wish, but only every other day is required.)
7.
Read the approximate sunspot longitude from the grid.
Record your observations on the table below:
Sunspot Number: ____3363
________
Recording Day
Date of Observation
Sunspot Longitude
1
July 9, 2023
2
July 11, 2023
3
July 13, 2023
4
July 15, 2023
5
July 17, 2023
6
July 19, 2023
After 10 days of observations (10 days after the first observation, not 10 observations because you are
recording the position every 2 days, not every day), estimate the rotation period of the Sun based on the
change in longitude of the spots over this time interval. For example,
if P is the full rotation period and X is the change in longitude of a particular spot in 10
days, then we can find the period from: X=Longitude at day 10 – Longitude at day 1
P/10 [days] = 360/X [degrees]
To be submitted electronically:
1)
The six
downloaded images used in the project (10 points). Images should include: a.
dates of observations (10 points)
b.
sunspot numbers (5 points)
2)
The grid you used to find the longitudes of the sunspot. The grid needs to have:
a.
all the positions of the sunspot over the 10 day period. (20 points)
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Felicia Wilks
b.
An empty grid receives 0 points.
3)
The completed table you used to record the observations. (25 points)
4)
Your calculation of the Sun’s rotation period based on your 10 days observation. a.
include all steps and show all your work (25 points)
b.
correct final answer (5 points)