Moon Project Notes
 Begin observation facing South:
-This is easily done by standing in the mall area and facing Coffman.
 Date: day and month observation are taken
 Clock time: standard AM/PM time of observation
 Decimal CST: means military time. 24 hour clock. Minutes expressed as decimal.
EX: 9:45 AM = 9.75 in decimal CST
6:15 PM = 18.25 in decimal CST
 Sun’s HA: Sun travels about 15° across the sky in an hour. So at noon, when Sun is
directly over head, it’s hour angle is 0. Every hour after /before noon
adds/subtracts 15 to the hour angle. The equation to calculate the Sun’s HA is:
Sun HA = (CST - 12.0) x 15.0 = ____degress
 Phase Sketch: Shade part of the moon NOT illuminated by the Sun.
 Phase Number: See figure on page 4: match the moon you observed with the
corresponding picture and number.
 Fists or Hands: The meridian is an invisible line that goes directly over head running
from North to South. We will measure the moon’s position as its angle from the
meridian, by sticking your arm out straight and counting the number of side-byside fists it takes to reach the moon from the meridian.
NOTE:
East of meridian = (-)°
West of meridian = (+)°
 Moon HA: This value is calculated from your observed number of fists and your
degrees/fist value, which you will calculate in lab. The equation is:
Moon HA = (# of fists) x (degrees/fist) = ____ degrees
 Moon’s Elongation: This is the angle set up by connecting lines from the Moon to the
Earth and from the Earth to the Sun. The equation is:
Elongation = Sun HA – Moon HA
NOTE: Elongation should always be positive (+), so if you calculate value is
negative (-), add 360 to it.
EX: Sun HA = -105°, Moon HA = 15°
Elongation = -105° - 15° = -120° + 360° = 240°
 Day Number: See table on page 7. EX: September 25th = 268
 You can look up moonrise/set times at:
http://aa.usno.navy.mil/data/docs/RS_OneYear.php
The closer to the meridian the moon is, the less error there will be in your
measurements. I encourage you to check out this website before you take observations so
that you will know where the moon should be at the time of your observations, i.e. you
will know if your observation is good or not!
 You must also enter your observations online!