29:52 Homework Set #1

Assigned: January 30, 2004

Due: February 6, 2004

Confused? Don’t go around miserable and despondent! Ask for help and explanation from me or the teaching assistant. Even better, work on these problems with one or two of your classmates. Always give your reasoning, not just a number.

1.On January 30, 2001, the celestial coordinates of Saturn were RA=3h29m, DEC=+16d47m. Describe where it is was in the sky. That means, find out what constellation it is in, how close it is to any prominent stars, and where it is relative to the ecliptic and the celestial equator.

2.Compare the position of Saturn at that time with its current position (see class notes, Addenda). Is it the same or different. If different, why is it different?

3.You see a flying saucer in the sky! Not wishing to be dismissed as a total lunatic by the authorities, you carefully estimate its coordinates in the horizon system as azimuth=50 degrees, altitude angle = 80 degrees. In what part of the sky did you see it, i.e. what direction and how high up?

4.The island of Kauai (in the Hawaiian chain) is at a latitude of 22^°. How high above the northern horizon is the pole star Polaris?

5.Directly south of Iowa City is Natchez, Missippi. It has (nearly) the same longitude as Iowa City, but is 10 degrees of latitude further south. You observe that the Sun is transiting here in Iowa City (local noon). What will an observer in Natchez see, i.e. is the Sun before transit, after transit, higher in the sky than here in Iowa City, lower,…etc. Give brief reasons for your answer.

6.In the constellation of Taurus the Bull there is a star with an inhabited planet, Planet X. Like the Earth, planet X has a significant tilt to its rotation axis, so seasons are quite pronounced. The length of the year is 180.50 days. The inhabitants of Planet X don’t want to bother with leap years and the like, and have a calendar with ten months of 18 days each. How many years will it be before the first month of their year (which is chosen to be in the middle of winter) occurs in summer instead?