Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.

What is in the Sky Tonight?

Tonight we will learn how to use several different tools for predicting "What is visible in the sky tonight?" This will come in handy for future meetings, when it's clear and we can do some observing.

You should write up a short report, answering each of the questions below, and turn it in at the end of tonight's session. Make sure your report contains:

First, let's look at the Skygazer's Almanac.

  1. What time does the sun set tonight? (answers to within half an hour are okay) What time does it rise tomorrow morning?
  2. Figure out the date on which this lab class will last meet. What date is it?
  3. What time does the sun set and rise on that date?
  4. When does the moon rise tonight?
  5. What is the moon's phase tonight? If the moon is more than half full, it will tend to shine so brightly that faint objects will be invisible.
  6. What is the moon's phase on the date of the last class meeting?
  7. The star Sirius is in the constellation Canis Major. What time does it set tonight?

Next, turn to the Star and Planet Finder (also known as a planisphere).

  1. Find the constellation Canis Major, and the star Sirius. Use the Finder to figure out what time the star will set tonight.
  2. Does the planisphere's answer agree with that of the Almanac?
  3. When will Canis Major set on the last day of lab? Will you be able to see it after 8 PM on that date?
  4. Find the constellation Pegasus on the planisphere. Use Pegasus to find Andromeda, and look in Andromeda for a spot marked "Galaxy". This is a big, bright, nearby galaxy. Where will it be at 9 PM tonight? Could we see it (if it were clear)?

Now, look at the book "Edmund Sky Guide". Go to the chart on page 17.

  1. Find the constellation Pegasus and the Andromeda Galaxy on this chart.
  2. According to this chart, is the Galaxy visible at 9PM tonight?
  3. Look at the charts at the back of the book. Find Pegasus again, and use it to find the Andromeda Galaxy. What are the celestial coordinates for the Galaxy?
  4. What are the celestial coordinates for the Pleiades?

Another sort of tool is a planetarium program on a computer. Here at RIT, we have installed the program "Sky Map Pro" on computers in lab 3335. The program is also installed on the Windows computers in the Gosnell Lab, 08-1335 and 08-1345.

  1. Figure out how to start the Sky Map Pro program (use the "RIT Startup" shortcut).
  2. If you are using the computers in the Gosnell Lab, take these two steps:
    • When the program starts up, it will ask for the name of a location with catalog data files. Type exactly as shown below, including the spaces between "SkyMap" and "Pro", and between "Pro" and "5.0".
                    \\coslabsrv01\SkyMap Pro 5.0\
    • After the main screen appears, click on the little icon of the Earth at the left edge of the screen and set the Observer's Location to Rochester, NY.
  3. Set the time and date for 9 PM tonight.
  4. Set the program so that it shows the sky on the southern horizon, with a 90-degree field of view.
  5. What constellations are visible above the southern horizon?
  6. Look to the northern horizon -- what constellations are visible there?
  7. Is the Andromeda Galaxy above the horizon at 9 PM tonight?
  8. Use the program to locate each of the 8 planets other than the earth. Which of them might be above the horizon at 9 PM tonight?

Later on this quarter, on a clear night, we will go outside and look at the Moon. For your final task this evening, please

  1. use the Almanac to figure out which of the nights we meet this quarter will occur when the Moon is within three days of first quarter
  2. use SkyMap Pro to determine the apparent angular size of the Moon on the first of these dates, at 9 PM. Express your answer in degrees
  3. look up the "field of view" of standard binoculars and a conventional telescope in the Edmund Sky Guide. The field of view of the unaided human eye is about 50 degrees.
  4. draw three circles, each two inches in diameter, on a sheet of paper. Label one "field of unaided eye", one "field of binoculars", and the last "field of telescope". These circles represent the field of view of each instrument.
  5. inside each of the circles, draw a half-circle representing the sunlit portion of the Moon. Make this half-circle the appropriate size, given the field of view

When we do go outside to observe the Moon, you will have to draw the features you can see on the Moon's surface with your unaided eye, with binoculars, and with a telescope. This should give you some idea of the relative amount of detail you may expect to see in each case ...

This page maintained by Michael Richmond. Last modified Mar 9, 2002.

Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.