Lab 2

LAB 2 - 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!

1.  Local Time

Give the current local time (whenever you are performing this lab).  Specify whether  we are on EST or EDT, and when (and how) this will change.

Interested in the time elsewhere? Try this:

http://www.timeanddate.com/worldclock/ 

2.  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:

http://tycho.usno.navy.mil/what.html

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?

3.  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.

4.  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.
Find the JD of the time of your birth.

5.  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.
When is the next leap year?
When was the last leap second added?

6.  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.

7.  The Lunar and Solar Cycles

Have a look at sunrisesunset.com. Determine (approximately) how the sunrise and sunset times change from day to day. Also determine how the moonrise and moonset times change daily.  What is the pattern, if there is one?

8.  Eclipses
Locate a source of upcoming lunar and solar eclipses.  Answer these questions:

Where and when is the next total solar eclipse?
Where and when is the next total lunar eclipse?
When will be the next total solar eclipse visible in North America?  Will there be more than one total solar eclipse visible in North America in your lifetime?

9.  Etcetera

Discuss any other times and/or calendars that are of interest to you.  Pick one calendar to discuss (at least for a paragraph or so).