Activity 5.1.4 – The Sun and its Sunspots
The Sun is the closet star to Earth and is
what supplies our planet with energy. It has a
variety of different features which have
significant impact on Earths environment.
One such feature is the Sunspots which
appear on the Sun’s surface.
The aim of this project is to count the
number of Sunspots on the surface of the Sun
over a period of time and determine any
cyclic patterns which may occur.
Part 1 – Analysing Recent Data
This section will require you to count the number of Sunspots that appear on images of the
Sun’s surface taken by an instrument on the satellite - Solar & Heliospheric Observatory
(SOHO). SOHO is a spacecraft which was launched on December 2, 1995. The spacecraft
orbits the Sun in step with the Earth, by orbiting around the First Lagrangian Point (L1).
(Note: a Lagrangian point is where the combined gravity of the Earth and Sun keep SOHO in
an orbit locked in a line with the Earth and Sun.) It contains 12 instruments and the images
which you will be looking at have been taken from the Michelson Doppler Imager (MDI).
The MDI takes images of the Sun’s structure within the visible spectrum of light. The
prominent feature within this range is Sunspots. They appear as dark spots on a yellow
background in the images.
1. Your task will be to look at all 50 images in the online file and fill out the table below.
Date image was taken
May 1996
January 1997
May 1997
November 1997
March 1998
June 1998
April 1999
July 1999
November 1999
March 2000
June 2000
October 2000
February 2001
May 2001
September 2001
No. of Sunspots in image
0
0
2
2
3
3
5
6
8
10
10
4
5
14
11
Activity 5.1.4 – The Sun and its Sunspots
January 2002
April 2002
August 2002
December 2002
March 2003
August 2003
November 2003
April 2004
August 2004
January 2005
May 2005
August 2005
January 2006
March 2006
May 2006
July 2006
October 2006
January 2007
April 2007
June 2007
August 2007
November 2007
January 2008
April 2008
June 2008
September 2008
November 2008
March 2009
May 2009
July 2009
November 2009
February 2010
May 2010
September 2010
January 2011
12
6
10
7
8
6
7
2
3
1
3
3
2
0
2
1
0
2
0
0
0
0
0
0
1
0
0
0
0
0
0
1
1
2
1
[A1] – Table neatly set out i.e. ruled
[A2] – Number of Sunspots are within plus or minus 2 sunspots
Activity 5.1.4 – The Sun and its Sunspots
2. Using the table you obtained in question 1, graph the data in an appropriate format.
Number of Sunspots on the Sun's Surface
16
14
N
u
m
b
e
r
S 12
u
10
n
s
8
p
o 6
t
o
s 4
f
Series1
2
0
Oct-95
Jul-98
Apr-01
Jan-04
Oct-06
Jul-09
Apr-12
Date
[A1] – correct shape
[A2] – title and axis are labeled
3. From your graph can you estimate when the minimum number of Sunspots would
have occurred?
Minimum occurs at approximately July 2008 but anywhere between January 2007
till July 2009 is fine.
[A1]
4. From your graph can you determine any cyclic patterns related to the number of
Sunspots appearing on the Sun?
Minimum occurs once every 11 years.
[A1]
5. What are some of the reliability issue with collecting the data this way?
a) We are only viewing half the sun so we are not counting every single
sunspot.
b) We are not looking at sun daily so dips in data cannot be verified.
Activity 5.1.4 – The Sun and its Sunspots
c) Difficult to calculate number of sunspots due to granulation of image.
Some Sunspots may not have been counted or likewise some spots counted
may not be Sunspots
[A1+A2] – 2 out of the 3 mentioned above
6. How could these issues be reduced?
a) View the whole Sun.
b) Look at Images on a regular basis daily or weekly.
c) Give a standard definition for when a dark spot on an image should and
should not be counted as a Sunspots to improve consistency
[A1+A2] – a reasonable solution for question 6
7. How do astronomers today count the number of Sunspots?
They count the number of Sunspot groups and then multiple this number by 10.
This is because over the decades they have discovered that Sunspots normally
appear in groups of roughly 10.
[A1]
Activity 5.1.4 – The Sun and its Sunspots
Part 2 – Analysing Past Data
The SOHO telescope has been in orbit since 1995, consequently, there are no images early
then this for us to analysis. Despite this, Astronomers have been keeping accurate records of
the number of Sunspots on the surface of the Sun since 1749. (Note: you should never ever
look directly at the Sun). In this section, you will use this data create a more accurate graph
from Part 1.
8. Use the data collected from NOAA to graph the year (x-axis) vs. the number of
sunspots.
Yearly Sunspot Numbers from 1700-2009
200
180
N
u
m
b
e
r
160
S
140
u
n 120
s
100
p
o 80
t 60
O
s
f
40
20
0
1700
1750
1800
1850
1900
1950
2000
Year
9. From your new graph do you notice any cyclic patterns? If so what is the period (in
years) of this pattern?
There is a cycle of maximums which occur once every 11 years or so.
[A1]
10. Using the data from your graph and your answer in Question 6, when will the next
solar maximum (the point at which the number of Sunspots are at their peak) occur?
Next solar maximum will occur in 2000 +11 years which is in 2011.
[A1]
11. Using the information you obtained in Question 6 when will the next solar minimum
(the point at which the number of Sunspots are at their lowest) occur?
Next solar minimum will occur in 2008+11 years which is in 2019.
[A1]
Activity 5.1.4 – The Sun and its Sunspots
12. How did astronomers like Galileo observe the number of Sunspots in the 1700’s and
what was wrong with what they did?
They observed the Sunspots through a telescope.
[A1]
This was a very dangerous activity because they were looking directly at the Sun
without any form of eye protection which can result in blindness.
[A1]
Part 3 – Further Research
Scientists are not just interested in how many Sunspots occur but they are also interested in
the questions below. In this section your task is to find out what scientists understand about
these questions and write a short paragraph which explains the current accepted
understanding.
13. Why is it important to monitor the number of Sunspots on the Sun with such
accuracy?
We need to monitor the number of Sunspots because the more Sunspots that
appear on the Sun the more likely Coronal Mass Ejections become. [A1]
CME’s are highly ionized particles which are spewed out from the Sun and can
often head towards earth. When these particles reach Earth they often disrupt
our satellites which causes problems with our telecommunications. Hence if we
know that there is a solar maximum we can take steps to reduce the impact on
our telecommunication devices.
[A1]
14. What causes Sunspots to appear on the Sun?
Sunspots are formed from the twisting of the Sun’s magnetic field.
[A1]
The magnetic field is twisted because the material at the Sun’s equator moves at
a much faster rate than the material at the poles. When this twisting is strong
enough it causes the magnetic field to push through to the surface where it is
viewed in the form of two sunspots.
[A1]
15. What causes Solar Flares?
Solar Flares occur when plasma gets caught in the magnetic field loop which juts
out of one Sunspot into the other.
[A1]
As a result a loop of plasma is seen to jut out from the Sun’s surface. [A1]