Name ________________
Date ________ Pd ______
USING CELESTIAL COORDINATES
Purpose:
The purpose of this exercise is to become familiar with the sky in general using celestial coordinates, and several classes of objects in
particular.
Procedure:
1. Here is a list of objects that can be found on these photographs:
Object Name
Orion Nebula (M42, NGC
1976)
Right
Ascension
Apparent
Magnitude
Declination
Approximate
Angular Size
arcminutes
Distance
from Earth
(pc)
05h, 35m
-05
3.0
60
490
Hercules Cluster (M15, NGC
16h, 42m
6205)
+36
5.9
17
1.02X104
Andromeda (M31, NGC 224) 00h, 42m
+41
4.4
100
8.9X105
Eagle Nebula
18h, 19m
-14
6.4
25
2100
The Pleiades
3h, 47m
+24
1.6
110
120
h
m
M101, NGC 5457
14 , 03
+54
8.2
30
8.2X106
M55, NGC 6809
19h, 40m
-31
7.0
19
5400
2. For each object,
A. In the last column of the table on pg 1, write the distance in scientific notation.
B. Plot your object on the celestial map using right ascension and declination
C. For D-F use the table above the map
D. Write the name of the object in the appropriate row
E. Draw a sketch
Distance in Sci.
Notation
F. Identify the type of object from the following list
 Bright Nebula: looks like a cloud (because it is a cloud in space). Stars are born in nebulae.
 Globular Cluster: spherical group of about 1 million (106) stars. Distinct from stars because rather than having
fuzzy edges, it has edges made of lots of dots.
 Open Cluster: loose cluster of a few hundred-few thousand nearby stars.
 Spiral Galaxy: In 3-D, a spiral galaxy looks much like a frisbee, but depending on which way you look at it, it
might be a circle, an ellipse, or a relatively thin line.
G. Answer the questions 1-2
Definitions and Fun Facts:
M (as in M31) stands for Messier, an early comet hunter, who was annoyed by the fuzzy, stationary objects in the sky which
he might easily confuse with comets. So he made a list of stationary fuzzy objects. The Messier objects are the brightest
extended objects in the northern sky other than planets.
NGC stands for New General Catalogue - now 100 years old - of extended objects.
Right Ascension and Declination are the coordinates of the sky, much like longitude and latitude on Earth
Apparent Magnitude is an indication of how bright an object appears to be. Apparent Magnitude runs backwards so that low
numbers are brighter objects (the Sun has apparent magnitude = -26) and high numbers are fainter objects.
One degree is 60 arcminutes (60'). The Sun and the moon are 30' in angular size.
1 pc = one parsec = 3.26 light years = 2X1013 miles. The nearest star is 1.3 pc away.
KEEP THIS PAGE IN YOUR 3-RING BINDER
Name ________________________________ Date __________ Pd ______
Questions:
1. Describe each of the object types as far, farther, or farthest away. (see your distances in the first table)
o Bright nebula:
o Globular cluster:
o Open cluster:
o Spiral galaxy:
2. Do you think that the types of objects you described as only 'far' exist at the 'farthest' distances as well? If so, why can't we see
them?