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APRIL 2010 VIEWING LIST
Object
Type
14” Scopes
Saturn
M81*
M82*
NGC 3079**
Regulus
M97*
M65*
M66*
NGC 3628**
M64**
(See Notes)
Gal
Gal
Gal
DS
PN
Gal
Gal
Gal
Gal
4” Refractor
M37
OC
Alpha Geminorum
DS
24 Comae Berenices DS
Size
21’
9’
8’
177”
8’
8’
14’
9’
15’
-
Distance
Coordinates
LY
LY
LY
LY
LY
LY
LY
LY
LY
09h 56’
09h 56’
10h 02’
10h 08’
11h 15’
11h 19’
11h 20’
11h 20’
12h 57’
+69 04’
+69 41’
+55 41’
+11 58’
+55 01’
+13 05’
+12 59’
+13 36’
+21 41’
4,400 LY
52 LY
-
05h 52’
07h 35’
12h 35’
+32 33’
+31 53’
+18 32’
12,000,000
12,000,000
50,000,000
77
2,600
35,000,000
35,000,000
35,000,000
19,000,000
Abbreviations:
MS = Multiple Star, EN = Emission Nebula, RN = Reflection Nebula, Gal = Galaxy, GC = Globular
Cluster, LY = Light Year, OC = Open cluster, PN = Planetary Nebula, SR = Supernova Remnant,
CS = Carbon Star, * = Video imaging optional, ** = Video imaging recommended
APRIL 2010 OBJECT DESCRIPTIONS
Saturn is guaranteed to be the most exciting object in the late spring sky. It is important to have some interesting stats for
the public as they observe this planet. See the last page of the Object Descriptions for relevant facts.
Note: The duo of galaxies below is fairly bright and is best viewed as a pair. Use the maximum magnification that
will show both in the same field of view. Try using the 4” and either the 22mm or the 31mm to observe the pair.
M81 is a spiral galaxy of 6.8 magnitude in the constellation Ursa Major (URR-suh-MAY-jer). Seen nearly face-on, it
resides 12 million Light Years away. Over 70 globular clusters have been discovered orbiting this galaxy. M81 and
adjoining galaxy M82 had a close encounter about 600 million years ago, resulting in a prolonged period of intense new
star formation that continues today.
M82 is an irregular galaxy of 8th magnitude in the constellation Ursa Major (URR-suh MAY-jer). Also known as the Cigar
Galaxy for it’s elongated shape, M82 is also about 12 million Light Years distant. The close encounter with M81 described
above distorted the shape of this irregular galaxy, creating considerable turbulence in its innermost regions. Over 100
globular clusters have been observed orbiting this galaxy.
NGC 3079 is an 11th magnitude spiral galaxy in the constellation Ursa Major (URR-suh MAY-jer). This galaxy is seen
nearly edge-on. It has an active stellar nucleus shrouding a supermassive black hole. Unseen are polar jets of high speed
particles which, slamming into clouds of interstellar matter, create a bubble extending 3,500 light years from the core.
Regulus , also known as  Leonis, is a young, type B, main sequence star of apparent magnitude 1.35. While it has 3 ½
times the mass of our Sun, Regulus has a rotation rate of only 15.9 HOURS. Theorists estimate that if the rotation rate
were only 17% faster the star would come apart.  Leonis is also a multiple star. Regulus itself is a spectroscopic binary,
while a companion some 177 arc seconds away is also a spectroscopic binary. While we can’t see the faint companions,
Regulus does appear as a nice double star in amateur telescopes.
M97, commonly known as the Owl Nebula, is a planetary nebula of 10th magnitude in the constellation Ursa Major (URRsuh-MAY-jer). In good seeing, and using a broadband filter, you may be able to detect two dark areas that form the eyes
of the owl-like image seen in photos.
M65 is a spiral galaxy in the constellation Leo (LEE-oh). Seen nearly edge-on, it displays a bright central core and a faint
oval corona that offers a hint of spiral arms. First listed by Charles Messier in 1780, M65 forms a fairly close grouping with
M66 and NGC 3628, described below.
M66 is another spiral galaxy in the constellation Leo that displays a more open aspect to the viewer. Due to a probable
close encounter with M65 in the past, M66 offers hints of a spiral arm extending away from the core suggesting a faint tail.
NGC 3628 is yet another spiral galaxy in Leo. Discovered by William Herschel in 1784,this edge-on spiral exhibits a
prominent dark dust band intersecting the bright core. Use a low magnification eyepiece on the 4” to determine if you can
observe all three faint galaxies at once.
M64 is a spiral galaxy in the constellation Coma Berenices (KOH-mah bera-NEE-seez, Berenice's hair). Popularly known
as the Black Eye Galaxy, this object has a diameter of about 51,000 LY. Steady seeing will offer viewers a bright irregular
shape with uneven brightness and texture. This is as a result of an unusual characteristic: the central portion of the galaxy
rotates in one direction out to approximately 3,000 light years, but the outer portion of the galaxy rotates in the opposite
direction! Where the two countra-rotating sections meet, the interacting dust and gas creates large areas of new star
formation, seen as brighter areas. How did this happen? It is probably the odd outcome of the collision of two galaxies in
the distant past.
M37 is an open star cluster in the constellation Auriga (aw-RYE-gah). At a combined stellar magnitude of 5.6, this cluster
extends across about 20 light years of space. Seen at low magnification, M37 displays a variety of star colors and a
network of dark lanes. This is one of the finest open clusters in the northern hemisphere.
Alpha Geminorum commonly known as the star Castor in the constellation Gemini (GEM-in-eye) is a fascinating triple
star with a secret. Each of the stars in this triple system is itself a spectroscopic double star. So when we gaze at Castor
we are in fact looking at a six star system. Star A (Magnitude 1.9) and Star B (mag. 3.0) orbit each other every 467 years.
Distant Star C is a faint 9th magnitude companion that orbits the A & B pair in a yet-to-be-determined orbital period.
24 Comae Berenices is a beautiful double star in the constellation Coma Berenices (KOH-mah bera-NEE-seez). The 5 &
6th magnitude pair are seen as intense orange and green. Use the lowest magnification that will clearly split the pair for
best color. What makes a star appear green?
SATURN FACTS
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Sixth planet from the Sun.
Second largest planet in the solar system.
Average distance from the Sun – 900 million miles
Current distance from Earth – 800 million miles
Diameter is approximately 65,000 miles at the poles, and 72,000 miles at the equator. Why the difference?
Average rotation period is 10 – 11 hours.
Orbital period around the Sun is 29.5 years.
Saturn has had observed wind speeds as high as 1100 miles per hour. Four times faster than wind speeds on
Jupiter.
The density of Saturn is only 0.7 grams/cubic centimeter. Less than water. The planet would float in water.
An interesting fact is that Saturn radiates more heat than it receives from the Sun. Scientists speculate on why.
Edge-to-edge diameter of the main ring system is over 180,000 miles
Average ring thickness is only about 1 kilometer (3,000 feet). Range is from roughly 200 meters to 3000 meters.
Number of major rings – 5. Thousands of minor rings
The rings appear edge-on about once every 14 ½ years. The rings are currently appearing at about a 3 degree tilt,
which also means that the major moons will be aligned well for observing.
34 named moons. Largest is Titan, second largest moon in the solar system. At 3200 miles in diameter, Titan is
larger than Mercury.
F. Lockhart