This is an assignment for next class. If you would like, you may begin working on it now, but I expect to give some time in class next Tuesday as well.
Assignment 1 - Time and Space
In this lab, you will investigate several ways of keeping time
in the universe. Measuring the passing of astronomical time is by no means a
trivial task - keep that in mind, as you find the current time according to
various websites. This lab is structured as a series of topics, followed by
questions and suggested websites. Have fun, and take your time!
Local Time
Give the current local time (whenever you are performing this
lab). Specify whether or not we are on EDT, and when (and
how) this will change.
Interested in the time elsewhere? Try this:
Universal Time and Greenwich Mean Time
UT is counted from 0 hours at midnight, with unit of duration the
mean solar day, defined to be as uniform as possible despite variations in the
rotation of the Earth. Find the current UT. The clock applet below may be
helpful:
UT is very similar to Greenwich
Mean Time (GMT), though this
term is not used often these days. Both are 5 hours ahead of EST. Is this
currently true? If not, why not? What is the current GMT?
Longitude and Latitude
These quantities give the location on the surface of the
semi-spherical Earth, by laying a grid atop it. Lines of longitude are measured
with respect to the Prime Meridian. Find the longitude of your hometown: Lines
of latitude are measured with respect to the equator. Find the latitude of your
hometown. Google maps may help.
Julian Date (JD)
Julian Day Number is a count of days elapsed since Greenwich mean
noon on 1 January 4713 B.C., Julian proleptic calendar. The Julian Date is the
Julian day number followed by the fraction of the day elapsed since the
preceding noon.
Find the current JD:
Calendar
Which calendar do we currently use?
What calendar was this switched from, and when?
Why was the switch made?
Does all the world use the calendar we do? Explain.
Sidereal Time
ST is time based on duration of the Earth's rotation with respect
to a point nearly fixed relative to the stars. Local Sidereal Time (LST) is
computed from ST using a longitude correction. Find the current LST.
The Lunar and Solar Cycles
Have a look at sunrisesunset.com. Determine how the sunrise and
sunset times change from day to day. Also determine how the moonrise and
moonset times change daily.
Etcetera
Discuss any other times and/or calendars that are of interest to
you.
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