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AST A01H Celestial Sphere Tutorial
This exercise is intended to familiarize you with the Celestial Sphere. It is not to be handed in for
assessment and should be thought of as a practice session. You will continue this learning exercise
next week with the same set of questions. Really make sure you understand how the sphere works
because in the third tutorial you will be quizzed with a new question sheet that requires the celestial
sphere as an aid (this is Quiz 1). You will not have an opportunity to ask your TA questions that
day but you may still work with a partner (or two) on the quiz. This (or similar) material may
appear on the midterm or ﬁnal exam.
1) Locate, or determine how to set, the following parts of the sphere and its components:
a) The Earth’s north and south poles, and the Earth’s equator.
b) The horizon and zenith.
c) The compass directions (N, S, E, W).
d) The altitude and azimuth scales.
e) The north and south celestial poles, and the celestial equator.
f ) The circles of right ascension (RA) and declination (DEC).
g) The Sun and the ecliptic.
h) The equinoxes and solstices.
i) The direction of the stars’ diurnal motion and the Sun’s annual motion.
2) Toronto has a latitude of +45◦. Set the globe for Toronto, and the Sun’s position for July 1.
a) What are the RA and DEC of the Sun?
b) What is the Sun’s azumith at Sunrise? At sunset?
c) For how long is the Sun above the horizon?
3) How long is the Sun above the horizon in Toronto on March 21?
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