Before starting this activity read the handout about planisphere basics
and the handout about
things everyone should know about astronomy
. Also, The Planisphere, Part I
completed before beginning this activity.
The Planisphere as a Tool
The planisphere can be used as a tool to predict the way the sky will look
at any time and date. In this activity you will use a planisphere to answer
a series of questions about the night sky. In addition you may use The Sky
software (or other planisphere software, if available) and the Internet to
aid you in answering the questions and constructing your own original
The planisphere has no way to show the movement of the Sun (which blocks our
view of the stars during the day). You will have to be conscious of the
rising and setting of the sun as a factor in answering the questions. Also,
daylight savings time is in effect at certain times of the year. When it is
in effect drop the planisphere back by one hour to view the sky as it
actually will be.
All times EST, not DST
Add one hour to get Daylight Savings Time.
In 2007, daylight time begins on March 11 and ends on November 4.
In 2008, daylight time begins on March 9 and ends on November 2.
The time of sunrise is earlier by ~2 minutes every day from the Winter
Solstice to the Summer Solstice.
The time of sunset is later by ~1 minute every day from the Winter Solstice
to the Summer Solstice.
The time of sunrise is later by ~2 minutes every day from the Summer
Solstice to the Winter Solstice.
The time of sunset is earlier by ~1 minute every day from the Summer
Solstice to the Winter Solstice.
For more exact times see the Table of Sunrise/Sunset at The US Naval Observatory Astronomical
Applications Data Services
Some of the following questions require you to remember material covered in
class or to use your textbook or other sources to look up the answers. All
questions assume that you are observing the sky from a northern hemisphere
mid-latitudes location such as Scarborough, Maine. Use a separate
piece of paper to answer the questions. Some questions require you to draw a
picture. All questions should be answered carefully and thoroughly:
you will be tested on the information you learn in the course of answering
- What is the north celestial pole (NCP)? What
important star in the sky is near the NCP?
- What is the celestial equator? What is the south
celestial pole? Draw a picture to illustrate your answers to these and the
- What is the meridian? What is it called when stars,
planets, the sun or the moon crosses the meridian?
- What is the zenith? What is the nadir?
- What is altitude?
- What is azimuth? How does the azimuth of an
astronomical object depend on the observer’s location (latitude and
longitude)? Choose a star on your planisphere and consider how its altitude and azimuth changes for people in different time zones. Draw pictures to illustrate your answer.
- What is the Winter Solstice defined in terms of the
location of the Earth in its orbit and the tilt of the Earth? What effect
does this geometry have on the weather in the northern hemisphere of the
earth? On the southern hemisphere?
- Define the Summer Solstice in the same way.
- Define the equinoxes, Spring and Fall, in the same
- What is the ecliptic? Draw a picture to illustrate
- What constellations does the Sun pass through as it
travels along the ecliptic?
- What name does this collection of constellations
have? When, that is, during what month(s), does the Sun pass through each
- Look up the dates given in books of Astrology for each Sun Sign (the signs of the Zodiac). Compare them to the times when the Sun is actually in those constellations. What’s going on?
- Draw a picture of the ecliptic and show the
location of the sun against the background of stars and using the celestial
equator and celstial poles at each solstice and equinox. You should include
at least the constellations of the Zodiac. Label the month during which the
Sun passes through each constellation. (Hint: draw a rectangle with lines
like a mercator projection map showing vertical lines similar to longitude
lines and horizontal lines like latitude lines. The line of 0° latitude
is the celestial equator. The ‘latitude’ lines are called
Declination. The ‘longitude’ lines are called Right Ascension.
Zero degrees Right Ascension is the point which we call the spring equinox.)
- What constellations are visible during the Summer months (June, July, August) from 9 pm to midnight? During what months are these constellations visible from 2 am to 5 am?
- What constellations are visible during the Fall months (September, October, November) from 9 pm to midnight? During what months are these constellations visible from 2 am to 5 am?
- What constellations are visible during the Winter months (December, January, February) from 9 pm to midnight? During what months are these constellations visible from 2 am to 5 am?
- What constellations are visible during the Spring months (March, April, May) from 9 pm to midnight? During what months are these constellations visible from 2 am to 5 am?
- How many angular degrees does the sky move through each day? Calculate the number of degree the sky moves each hour.
- How many angular degrees does the Sun move each day? Each month? Each season? Use your illustration of the ecliptic to answer these questions.