Astronomy Laboratory Manual - Hartnell College
AST 1L
Lab Module 1
The Observing Project
The Location and Time of Sunset OR Fremont Peak
Observatory
Due Date: The last lab class before finals
I.
The Location and Time of Sunset (Worth 15 points + 10 points
Extra Credit)
Background
Science depends on observations – particularly careful, well-documented observations.
This exercise requires that you make a series of observations and collect them
systematically in a notebook that will be handed in at the end of the semester.
Equipment
Camera; notebook; pencil; compass (recommended)
Objectives
You will track the seasonal changes in the time and location of the sun over the course of
the semester by observing sunset (or sunrise) at least once every other week for at least
eight consecutive weeks (a total of 4 observations) and photographing your
observations.
Background
At this very moment, you might be nice and relaxed, sitting in a comfortable chair,
reading this lab manual. You are probably completely unaware that you are literally
hurtling through space as you read this sentence. With every beat of your heart, you are
propelled more than 10 miles through our Solar System, more than100 miles through our
galaxy! Indeed, the Earth is not a stationary point in the Universe. Its motion results in
changes in the observed night sky – changes that have been noticed by humans for eons.
City lights and prime-time TV have eliminated our intimacy with the night sky,
especially since the average person no longer relies on this intimacy for survival. We
will try to recover some of this knowledge now by systematically observing the Sun.
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Lab Module 1: The Observing Project
Astronomy Laboratory Manual - Hartnell College
AST 1L
The orbital motion of the Earth about the Sun results in some obvious changes in the
night sky. For instance, you can see the constellation of Orion, the hunter, in the January
night sky while Sagittarius makes its debut in July when the Earth is on the other side of
the Sun. There are, however, some less obvious changes that occur due to the tilt of the
Earth’s rotational axis relative to the plane traced out by its orbit about the Sun. This
little “accident” of nature results in the seasons experienced (and enjoyed!) north and
south of the equator. More specifically, the tilt causes the Sun to rise and set at different
locations and times depending on the time of year and your location (latitude) on the
Earth. The purpose of this lab is to get you to observe this phenomenon yourself. You
are the scientist. The question you will investigate is: “where and when does the Sun set
(or rise) each day (week)?”
As a precaution, you should not look directly at the Sun (even through a camera lens)
before it sets as it could cause severe eye damage!
•
Choose and describe your location: Choose some observing location with a
reasonably unobstructed view of the western horizon (or eastern if you prefer to
observe sunrise). The view of the horizon should have at least one reference
landmark. The reference landmark that you choose will help you to determine
the direction of motion of the Sun and how far it moves every day. Examples of
landmarks include a tree, building, telephone pole, edge of a cliff. Sketch the
location on your paper. Describe in detail the exact location from which you
made your sketch and indicate on your picture which landmark you chose
as the reference. It is important that every time you make an observation of
the rising or setting Sun, you will need to return to this exact location and
look towards the same direction, so be very specific in your description.
•
Determine time of sunset: Before each observation you need to find out the
time of sunset (or sunrise) by going to the internet site:
www.almanac.com/rise
Enter the date, the city, and state of your observing location. Do NOT
photograph the sunset (or sunrise) at the same time every week as the sunset
time will change!
•
Record date and time of sunset from the website: Important: include whether
the time is Pacific Standard Time or Pacific Daylight Time.
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Lab Module 1: The Observing Project
Astronomy Laboratory Manual - Hartnell College
AST 1L
•
Measure and record the angular distance of the sunset from the reference
landmark: Use the reference landmark on the horizon to determine the Sun’s
location. Use your fist and thumb to determine approximately how many degrees
horizontally in the sky it is away from the reference landmark (that is measure it’s
angular distance from the landmark). One fist represents about ten degrees in
the sky and 1 thumb represents about 2 degrees in the sky. Record the value
of the angular distance in degrees.
•
Take a picture of the Sun when it is starting to touch the horizon: Once every
other week, return to your observing location and watch the sunset (or sunrise).
For each observation, you should make sure to allow yourself plenty of time to get
to the observing location before sunset. Ideally you should get there
approximately 20 minutes before sunset. You should take a picture of the Sun
when it is low in the horizon, before it actually sets. As a precaution, you
should not look directly, or through the camera at the Sun before it sets as it
could cause severe eye damage!
•
Continue to make Sun observations at least once every two weeks (doesn’t have
to be the same day) throughout the semester. Obtain at least 4 cloud free
observations during a minimum of 8 weeks of observations. IT IS
IMPORTANT TO KEEP THE CAMERA ON THE SAME ZOOM EVERY
TIME YOU PHOTOGRAPH IT!
•
Determine and label the direction of North and South: Remember that the Sun
sets in the West and West is always left of North. Turn so that the Sun is directly
to the left of you. Then the direction you are facing is North and the opposite
direction is South. If you are observing the sunrise, remember that the sun rises in
the East and East is always right of North. In this case, turn so that the Sun is
directly to the right of you. Then the direction you are facing is North and the
opposite direction is South. Label North and South on your photos.
•
If it is cloudy that week, do your observations the following week. You should
attempt to get at least 4 good (cloud free) observations of the sunset over a
minimum of 8 weeks.
•
Once your observations are all complete, paste or tape your photographs neatly
onto a sheet of paper. You can also print them out if they are digital photos.
You may either put them all on one piece of paper if they can fit or choose to put
each photo on its own sheet. Above each observation label the date, sunset time,
and the angular distance of the Sun. Label North and South on each photograph.
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Lab Module 1: The Observing Project
Astronomy Laboratory Manual - Hartnell College
AST 1L
Interpreting Your Results
At the end of the semester, summarize your findings regarding sunset (sunrise) on a page
in your observing notebook. As you describe your findings, answer the following
questions:
1) How many TOTAL degrees did the position of sunset (sunrise) move between your first
and eighth week of observation. Was the position of sunset moving northwards or
southwards during the 8 weeks of observations?
2) How did the time of sunset change over the course of the semester (i.e. was it setting earlier or
later)? How many total hours or minutes did it change from the first observation to the eighth
week? To do this correctly, you must consider whether or not your time measurements were
in STANDARD or DAYLIGHT time and subtract or add an hour to compensate for the time
change if there was a time change during your observations.
3) What do you think is causing the changes in sunset location and time?
4) During the next six months after your last observation, how will the time of the sunset or
sunrise change? Will the location of sunset or sunrise move northwards or southwards?
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Lab Module 1: The Observing Project
Astronomy Laboratory Manual - Hartnell College
AST 1L
II.
Fremont Peak Observatory Field Trip (Worth 15 points alone or 10
points additional extra credit if the Sunset Project is turned)
Equipment
Flashlight with red cellophane; notebook; pencil
Objectives
You will obtain the opportunity to visit Fremont Peak Observatory and view astronomical
objects through telescopes.
Important Note: If you are in the lecture class, you will automatically receive credit for
one of the observing projects if you choose to go on this field trip. To ensure proper
credit, make sure you indicate on the cover page of your write up that you would like
credit for this in the lecture also. The public talk is extra credit for the lab and lecture.
Introduction
Fremont Peak Observatory is located in the beautiful Fremont Peak State Park in San
Juan Bautista. It is about a 1 hour drive from Salinas. The road up the mountain is
very windy and at times steep. Be very careful when driving at night.
The date of the field trip will be announced several weeks ahead of time in class. The
entire observing experience should last until about 10:00pm. Dress warmly and bring a
flashlight that is covered with red cellophane. You can also bring your planisphere
with you. Once you arrive at the observatory, please be courteous. The staff at Fremont
Peak Observatory are providing us with a service by allowing us to access their
observatory; please respect them and the facilities.
You can find out all the information (including directions) on their website:
www.fpoa.net. Or you can call them: (831) 623-2465. Bring $6.00 in correct change
for the parking fee.
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Lab Module 1: The Observing Project
Astronomy Laboratory Manual - Hartnell College
AST 1L
Part I: Telescope Observations
1. Once you arrive at the observatory, there should be several telescopes set to view
different objects in the sky. Sketch at least three objects. Take some time to
look through the telescope. Do not move the telescope! Try to capture the image
in your mind. Don’t sketch the object as you are observing it through the
telescope. Draw the object afterwards in order to let others have a chance to
observe the object.
2. Make sure that your drawing is to scale with the eyepiece.
3. Write a sentence describing what the object looked like.
4. Also fill in all the required information. If you don’t know the information, ask
the people who are operating the telescope.
Part II: Instructor’s Signature
This is very important. In order for you to obtain credit for this assignment, you must
ask your instructor or Fremont Peak volunteer to sign your observations sheet.
Part III: Journal Entry
1. Your journal entry should be at least 400 words typed.
2. Describe your thoughts from the time you drove up the mountain until you came
back down.
2. Describe the objects you saw. Which one fascinated you the most and why?
3. What was the weather like?
4. Did you do anything else besides look through the telescope?
5. What did you think about the entire experience?
Note: By choosing to go to Fremont Peak Observatory, you assume all liabilities.
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Lab Module 1: The Observing Project
Astronomy Laboratory Manual - Hartnell College
AST 1L
Instructor’s or Volunteer’s Signature:
Object 1:
Object Name:
Date/Time :
Telescope Diameter:
Draw what you see through the telescope above.
Describe in words what you see here:
Extra Credit:
Focal Length – Objective:
– Eyepiece:
Magnification=Fobj/Feye:
Object 2:
Object Name:
Date/Time :
Telescope Diameter:
Draw what you see through the telescope above.
Describe in words what you see here:
Extra Credit:
Focal Length – Objective:
– Eyepiece:
Magnification=Fobj/Feye:
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Lab Module 1: The Observing Project
Astronomy Laboratory Manual - Hartnell College
AST 1L
Object 3:
Object Name:
Date/Time :
Telescope Diameter:
Draw what you see through the telescope above.
Describe in words what you see here:
Extra Credit:
Focal Length – Objective:
– Eyepiece:
Magnification=Fobj/Feye:
Object 4:
Object Name:
Date/Time :
Telescope Diameter :
Draw what you see through the telescope above.
Describe in words what you see here:
Extra Credit:
Focal Length – Objective:
– Eyepiece:
Magnification=Fobj/Feye:
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Lab Module 1: The Observing Project