Assignment 1
				PSci 21, Elementary Astronomy
				Spring 2002 MWF 12-12:50
				Assigned 2001 February 6

Due as a paper copy at the beginning of class, Friday, February 15.  
Sorry, but no late assignments can be accepted: it just isn't possible for
classes this size.

Use other pages for this assignment.  If you write everything on this page
and hand it in, it will be so crowded it'll look terrible!

Always show all work.  Always write the units.  Always do your best.  
Make attempts at everything.  If you have trouble, please come to office
hours in McLane 11, MWF 1-3 p.m, and at other times by appointment


The Cosmic Calendar on Three Number Lines:
------------------------------------------

(a) Take a ruler, turn a blank 8.5-inch x 11-inch piece of paper sideways,
and, with a pencil, draw a line 26 cm long.

Let this line represent the age of the Universe, 13 billion years.  Draw
tics down this line every 2 cm, starting at zero at the beginning of the
line.  Label the tics to represent each billion years, starting with the
beginning, 13 billion years ago, and ending with now, or 0 years ago.  
(Label the tics with the numbers counting down: 13, 12, 11, ... , 3, 2, 1,
0 billion years ago, which is now.)

On this number line, mark and label all the events described in The Cosmic
Calendar, in the Class Notes (and available online at
http://zimmer.csufresno.edu/~fringwal/calendar.txt).  Don't include the
events in the last 500 million years: if you do, it'll get crowded.  
Write the real dates (e.g. 300,000 years after the Big Bang).  Don't write
the relative dates scaled to the calendar (e.g. January 1, 12:12 a.m.).

An example of a similar number line is printed on the other side of this
page.  Your assignment doesn't have to be this fancy (you need not draw
the little pictures of dinosaurs), but it does show basically what to do.

This isn't supposed to be a technical or difficult assignment.  Follow the
directions carefully, pay attention to detail, and use your common sense.
An event that happened 9.5 billion years ago didn't happen 9.5 bilion
years after the Big Bang: it happened 9.5 billion years _ago_, or 9.5
billion years _before now_.  This means this event happened 3.5 billion
years after the Big Bang (since 13.0 - 9.5 = 3.5).  Mistakes students
often make with this assignment are: (1) Forgetting that each tic should
stand for 1 billion years; (2) Forgetting part (d) (see below).

(b) Repeat (a) on another piece of paper, but this time, for the events of
the past 500 million years.  If we didn't include these in (a), because
the labels would have become crowded.  This time, draw a line only 25 cm
long, with tics down this line every cm.  They will represent 20 million
years each.  Label all the events between 500 million years ago and
100,000 years ago.  Don't include the events of the past 100,000 years: if
you do, the labels will get crowded again.

(c) Repeat (b) on another piece of paper, only this time for the events of
the past 100,000 years.  Draw a line 25 cm long, with tics at every cm.
They represent 4,000 years each.  Label all the events between 100,000
years ago and now.  It still gets crowded at the end, doesn't it?

(d) In your own words, briefly describe the punchlines and following
ideas, listed at the end of the Cosmic Calendar. _Use your own words_.
Don't copy them from the Cosmic Calendar, that's plagiarism.