Chapter 2 Constellations 1 - the Home Page for Voyager2.DVC.edu.

12
Chapter 2 The Constellations
The constellations are formally named patterns and areas of the sky. Ancient people named the patterns
they found from their locations. Different peoples found very different patterns and named them
differently. Even the choice of stars to combine varies. ‘
Many of the constellations we use today first started with the Babylonians and were modified by the
Greeks. The Romans seem to have adopted the Greeks’ constellations. During the Dark Ages in western
Europe, the Islamic world maintained the knowledge of astronomy developed by the Greeks. Most of our
common star names are Arabic names developed during this time. Not every visible star was used to
make the named pattern. The Greeks and Romans had no names for stars or patterns too far south to be
seen from the Mediterranean area.
Europe awoke from the Dark Ages and became reacquainted with the Greeks’ knowledge starting around
1000CE (Common Era). The works of Plato, Aristotle and Ptolemy were translated into Latin (from
Arabic). These authors were more advanced than the Europeans of the day. So they were studied, not
challenged.
By the 1600’s and 1700’s CE, astronomers realized that there were unnamed parts of the sky and that
use of the telescope would lead them to find increasing numbers of stars. They proceeded to name
constellations covering all regions of the sky. Some of the names they chose, such as Telescopium,
attest to the modern origin of these constellations.
Astronomers extended the definition of a constellation to include a region of the sky and any stars
found within the region. The stars making up the traditional pattern are included in the boundaries, as are
any additional objects found within the boundaries. The constellation boundaries are shown in Figure 2-5.
A total of 88 constellations cover all directions. These constellations are used by astronomers planetwide.
Stars within a constellation are not normally associated in three dimensional space.
Other apparent star groupings are called asterisms. The stars in an asterism can belong to one or
several constellations. Asterisms can be likened to nicknames or names for neighborhoods. Many,
including the Big Dipper, Little Dipper, and Summer Triangle are very famous. Additional asterisms can
be created at will, but changing constellations requires the decision of the International Astronomical
Union (IAU).
You will be learning to recognize some of the more prominent constellations visible from the USA. The
table includes the constellations and asterisms we cover. For each constellation or asterism we learn
you will be responsible to know
st
a) Official name of the constellation (or asterism) – 1 column
st
b) Official meaning of the name (not what we think it looks like) –1 column
nd
c) Name(s) of first magnitude and other stars in the constellation –2 column
(Star names are bold. The other information in this block is for your observing
pleasure)
d) Find the constellation or any of the stars on a star map with no lines
e) Circle the stars in the constellation
f) Read the Right Ascension and Declination of a star or constellation from the map.
In a test or quiz the map will have no lines, no numbers, but tic marks will indicate where
the lines would be.
The data in the last column of the table expresses coordinates of (roughly) the middle of the constellation.
They are not the coordinates of any particular star in the constellation. Their purpose is to allow the reader
to find the constellation (or to explain to another where it is) if he had no idea. There is no reason to
memorize these values if you can find the constellation on a map. Do NOT use these coordinates for stars.
You will be using the names and positions of stars and constellaions in some of the exercises concerning
what can and cannot be seen from different locations and at different times. You are expected to get the
information from on a map without lines.
Constellations retain their positions relative to one another, but their position relative to the horizon
changes as the Earth spins. So it is handy to use one to find another, rather than to count on using the
horizon or land-based references to find them.
Chapter 2
Constellations
1
13
Name/
meaning
Andromeda
(And) name
(daughter
of
Cassiopeia)
Aquila
(Aql) eagle
Auriga
(Aur)
charioteer
Boötes
(Boo) herdsman
Cancer
(Cnc)
crab
Canis Major
(CMa)
large dog
Canis Minor
(CMi) small dog
Cassiopeia
(Cas)
Her name
(a queen)
Cepheus(Cep)
His name(a king)
Corona
Borealis (CrB)
northern crown
Cygnus
(Cyg)
swan
Delphinus
(Del) dolphin
Draco (Dra)
dragon
Gemini (Gem)
twins
(Castor and
Pollux )
Hercules
(Her)His name
Leo
(Leo)
Lion
Lepus
(Lep) hare
Libra (Lib)
balance scale
Chapter 2
Features and Bright Stars
Approx
Location
M31 Andromeda Galaxy at RA
00 hr 42.7 min, Dec
+41°16', Naked Eye
Andromeda's head is shared with Pegasus
γ And (Almak) Bright Binary K2 and A0, Eastern "foot"
α Aquilae is Altair, First Magnitude from Flying Eagle,
Southernmost part of Summer Triangle
α Aurigae is Capella First Magnitude
M36(RA 5 hr 36.1m, Dec +34°8') and nearby M37, M38
Open Clusters
α Boötis is Arcturus, find Using Big Dipper Handle, Kite
Shaped, ε is triple, incl. visual Binary "Pulchrissima"
M 44, Praesepe (RA 8 hr 40.1m, Dec +19°59') a star
cluster best seen in binoculars
α Canis Majoris is Sirius brightest apparent , Double with
White Dwarf
M41(RA 6 hr 47.0m, Dec -20°44') open cluster
α Canis Minoris is Procyon first magnitude, with white
dwarf companion
Relatively bright γ is a Variable star changing from 1.6 to3.
mag (middle of W)
M103 (RA 1 hr 33.2m, Dec +60°42') open cluster is near δ
Tycho Brahe found a Supernova here
Not Bright,
δ Cepheii is variable and is distance
benchmark
T Cor Bor, (not naked eye) has brightened twice(1945,
1866) to mag 2, drops to 15 near ε Cor Bor
RA 1 hr ,
Dec +40 °
α Cygni is Deneb, "bird's tail", first Mag is northernmost,
Southern end (β) is Albireo fine blue and yellow binary
North America Nebula 3 ° E of Deneb
East of Summer Triangle,
No bright stars, but distinct pattern
Extends between Ursa Major and Ursa Minor, all faint stars
RA 20 hr 30
min Dec +40°
RA 19hr 30min
Dec +5°
RA 5 hr 30 min
Dec +40°
RA 15hr 30min
Dec +30°
RA 8 hr 30 min
Dec +20°
RA 7 hr
Dec-25°
RA 7 hr 30 min
Dec + 5°
RA 1 hr
Dec +60°
RA 22 hr
Dec +70°
RA 15 hr 45
min Dec + 30°
RA 20 hr30min
Dec +15°
RA 10 to 21 hr
Dec +65°
α Geminorum, the fainter, is Castor, is Westward and RA 7 hr
Dec +25°
triple,
β Geminorum, the brighter, is Pollux is Eastward,
both first magnitude
M35 (RA 6 hr 8.9m, Dec +24°20')
M13 (RA 16 hr 41.7m, Dec +36°28') fine globular cluster
RA 17 hr
Dec +30°
α Leontis is Regulus, first magnitude, the Stella Regina for RA 11 hr
Dec +17°
Greeks, many occultations,
β Leontis is Denebola, Arabic for "Lions Tail"
M65(RA 11 hr 18.9m, Dec +13°05') Spiral Galaxy
M66(RA 11 hr 20.2m, Dec +12°59') Spiral Galaxy
M95(RA 10 hr 44.9m, Dec +11°42') Spiral Galaxy
M96(RA 10 hr 46.8m, Dec +11°49') Spiral Galaxy
No bright stars, below Orion
RA 5 hr 30 min
M79 (RA 5 hr 24.5m, Dec -24°33')rich globular star cluster Dec -20°
Faint stars, was part of Scorpius (a claw), renamed in RA 15 hr,
honor of Augustus Caesar for justice and reform of Law
Dec-15°
Constellations
2
14
Lyra (Lyr)
lyre
Monoceros
(Mon) Unicorn
Orion (Ori)
name
(a hunter)
Pegasus (Peg)
His name,
(winged horse)
Perseus
(Per)
His name
(a hero)
α Lyrae is Vega, first magnitude; will be pole star in ~ RA 19 hr,
Dec 38°
13,000 years, β Lyrae is eclipsing binary, with gas shells
M57 (RA 18 hr 53.6m, Dec +33°2')planetary nebula
Faint, between Orion and Canis Major
RA 7 hr
Dec -5°
RA 5 hr 30 min
α Orionis, Betelgeuse, is reddish
Dec 0°
β Orionis, Rigel, is a bluish system of five stars
M42 (RA 5 hr 35.4m, Dec -5°27' diffuse nebula, naked eye
No first magnitude stars, Large square with stars interior, RA 23 hr,
Looks like Baseball diamond
Dec +20°
M15 (RA 21 hr 30.0m, Dec +12°10') globular cluster
RA 3 hr 30 min
β is Algol an eclipsing binary with 2.87 day period
Double Cluster h and χ young open clusters in Milky Way Dec +45°
NGC 869 (RA 2 hr 19m, Dec +57°09') =h Persii
NGC 884 (RA 2 hr 22m, Dec +57°07') =χ Persii
Pisces (Psc)
All faint stars.
RA 1 hr,
fish
Dec +10°
Sagittarius
Trifid Nebula = M20=NGC6514
RA 19 hr
(Sgr)
(RA 18 hr 2.6m, Dec -23°02') diffuse nebula
Dec-25°
archer
Lagoon Nebula=M8=NGC6523
(anatomically a (RA 18 hr 3.8m, Dec -24°23') diffuse nebula
centaur)
Omega Nebula = M17=NGC6618
(RA 18 hr 20.8m, Dec -16°11') diffuse nebula
Scorpius
α Scorpii is Antares Temperature~3500°K, double RA 16 hr 45
(Sco)
M4=NGC6121 (RA 16 hr 23.6m, Dec -26°32') globular min Dec-30°
scorpion
cluster
M6=NGC6405 (RA 17 hr 40.1m, Dec -32°13') open cluster
M7=NGC6475 (RA 17 hr 53.9m, Dec -34°49') open cluster
Taurus
RA 4 hr 30 min
α Tauri is Aldebaran, about 3000°K
(Tau)
Dec +15°
Pleiades=M45, open cluster (RA 3 hr 47.0m, Dec+24°07')
bull
M1=Crab Nebula ,Supernova remnant
(RA 5 hr 34.5m, Dec+22° 01')
Hyades naked eye V shape, nearby galactic cluster
Ursa Major
Extends from
α Ursa Maoris is Dubhe, pointer nearer Polaris (double)
(UMa)
β Ursa Majoris is Merak, the other pointer, a single A1 star RA 8 -14 hr
great bear
Mizar, at the bend in the handle of the dipper, is triple. The Dec +60°
visible dimmer companion Alcor (the rider) is binary as
well
Ursa Minor
α Ursa Minoris is Polaris (other name Cynosura), variable RA 16 hr
(UMi) small bear by 0.1 magnitude with 31.97 day period
Dec +80°
Virgo
α Virginis is Spica, "ear of grain". Large cluster of distant RA 13 hr
(Vir) virgin
Dec +0°
galaxies in constellation
Asterisms: Summer Triangle (Deneb, Altair, Vega), Big Dipper (in Ursa Major),
Little Dipper (in Ursa Minor), and Winter Triangle (Betelgeuse, Procyon, Sirius)
Chapter 2
Constellations
3
14
15
UMi
Cam
Dr a
Cep
22h
60°
20h
60°
18h
60°
16h
60°
14h
60°
12h
60°
10h
60°
8h
60°
6h
60°
4h
60°
2 h Cas
60°
UMa
Lyn
Lac
Cyg
V ul
Peg
20h
30°
18h
Her
30°
CrB
16h
30°
Boo
14h
30°
Com
12h
30°
Sg e
22h
0°
10h
30°
A ql
20h
0°
1 8 hOph
0°
Se r
16h
0°
8h
30°
Gem
A nd
6h
30°
Tri2 h
30°
4h
30°
Tau
A ri
Cnc
Leo
Del
Eq u
A ur
LMi
Lyr
22h
30°
Per
CVn
Psc
CMi
14h
0°
V ir
12h
0°
10h
Se 0
x°
8h
0°
Mo n
6Ori
h
0°
4h
0°
2h
0°
Cet
Sct
A qr
Crt
PsA
22h
-3 0 °
20h
-3 0 °
Mic
Sg r
18h
-3 0 °
Sco
16h
-3 0 °
CrA
Tuc
Tel
20h
-6 0 °
Pav
14h
-3 0 °
Lu p
Gr u
Ind
22h
-6 0 °
Crv
Lib
Cap
A ra
18h
-6 0 °
12h
-3 0 °
8h
-3 0 °
Pu p
Pyx
2h
-3 0 °
For
Scl
Cae
14h
-6 0 °
Cru
12h
-6 0 °
10h
-6 0 °
Ho r
Car 8 h
-6 0 °
Pic
6h
Do r
-6 0 °
Ph e
4h
Re-6
t 0°
2h
-6 0 °
V ol
Men
Cha
Figure 2-1 Entire Sky, Mercator Projection with Labels
Constellations
4h
-3 0 °
V el
A ps
Chapter 2
6h
-3 0 °
Col
Cen
Mus
Oct
Er i
CMa
10h
A nt -3 0 °
No r
16h
-6 0 ° Cir
TrA
Lep
Hya
4
Hyi
15
16
Figure 2-2 Entire Sky, Mercator Projection No Labels
Chapter 2
Constellations
5
16
17
Figure 2-3 Northern Hemisphere with Labels
Chapter 2
Constellations
6
17
18
Figure 2-4 Northern Hemisphere No Labels
Chapter 2
Constellations
7
18
19
UMi
Cam
Dr a
Cep
Cas
UMa
Lyn
Lac
Cyg
Her
CrB
Tri
Gem
Com
Sg e
Del
Tau
A ri
Cnc
Leo
Psc
CMi
Se r
A ql
A nd
Boo
V ul
Eq u
A ur
LMi
Lyr
Peg
Per
CVn
Oph
Ori
Se x
V ir
Mo n
Cet
Sct
A qr
Crt
Lib
Cap
Crv
Sg r
PsA
Pyx
A nt
CrA
Lu p
Gr u
Tel
Ind
Pav
A ra
Pu p
Col
V el
Cir
Do r
Re t
V ol
Men
Cha
Figure 2-5 Constellation Boundaries (with Milky Way shaded)- Entire Sky
Constellations
Ph e
Pic
Car
Cru
Mus
Oct
Scl
Ho r
A ps
Chapter 2
For
Cae
Cen
No r
TrA
Er i
CMa
Sco
Mic
Tuc
Lep
Hya
8
Hyi
19
20
Figure 2-6 Southern Hemisphere with Labels
Chapter 2
Constellations
9
20
21
Figure 2-7 Constellations of the Zodiac, the Constellations Along the Ecliptic
Chapter 2
Constellations
10
21
22
Studying the Constellations
Don’t expect to ignore the constellations until the day before the test and then read and remember the
maps. Do repeat the constellations several times a week, if not every day. It will only take a few minutes.
Don’t just look at the constellations and hope they will sink in. Use as many of your senses as possible. Make lots of copies of the blank maps. As we learn a few more constellations in class, study them, then
fill in the blank map over and over until you can do it from memory. Start with the same parts each time,
so you can build on what you already know. The next time we learn a few more constellations, repeat the
process. Drawing the constellations involves you visually and kinesthetically (moving your body as you
draw). Say the names out loud and use the mnemonics or sing the constellation songs to involve your
aural (hearing) memory.
You should have two goals as you study the constellations, to do well on the tests and to learn the
constellations so that you can find them in the sky. These are somewhat different because the test will be
from the fixed maps, while the orientation of the constellations in the sky changes. What doesn’t change is the relative positions of the stars and constellations. So it is helpful to go from one recognizable
constellation to the next. This section shows how to go from the most obvious constellations to others.
The mercator projection is broken up as follows. The polar map has a separate sequence of
constellations.
UMi
UMi
Dra
Cep
Dra
Cep
2 2 h2 2 h
6 0 °6 0 °
2020
hh
6060
°°
1188hh
6600°°
16 h
16 h
60 °60 °
Arc to
Arcturus
1 4h 1 4h
6 0° 6 0°
12h
60°
12h
60°
CVn
Cyg
30°
V ul
Peg
Peg
CVn
30 °
18h
Her
3108°h Her
30°
CrB
16 h
1 4h
Boo
CrB
30
°16 h
3 0° 1 4h
Boo
Com
30 °
3 0°
12h
30°
Del
22h
Eq u
0°
22h
0°
Aql
20 h
0°
Aql
1 8 hOph
0°
A qr
Sct
1 8 hOph
0°
Se r
16 h
0° Se r
16 h
0°
Lib
Sct
Cap
1 4h
0°
Vir
Crt
Crv
22h
-3Cap
0°
Mic
22h
PsA
Gru
-3 0°
20 h
-3 0 °
Gru
CrA
20 h
-3 0 °
Sgr
20 h
-6 0°
-6 0 °
Pav
-60 °
Oct
Lib
1 4h
-3 0 °
16
Luhp
-3 0°
Sco
T el
CrA
22h
-6 0°
16 h
-3 0°
18h
-30 °
Ara
18h
Ind
22h
T uc
18h
-30 °
T el
1 0h
Se x0 °
16 h
Lu p
-6 0° Cir
T rA
Ara
18h
-6 0 °
Pav
-60 °
Aps 16 h
-6 0° Cir
T rA
1 4h
-6 0 °
-6 0 °
30°
30°
Ari
Tau
Ari
Mo n
8h
0°
Mo n
8h
-3 0 °
Pu p
1 0h
A nt -3 0 °
V el
1 0h
Pic
6h
-6 0 °
Pyx
Car 8 h
-6 0 °
-6 0°
6h
Ori
0°
12h
1 0h
Cha°
-60
-6 0 °
2h
0°
Cet
0°
Eri
6h
-3 0°
Col CMa
Cae
8h
-3 0 °
Pu p
2h
0°
Cet4 h
4 Lep
h
-3 0 ° For
6h
-3 0°
Col Ho r
Dor
4h
Re-6
t 0°
Men
Pic
6h
2h
Eri
-30 °
Scl
4h
-3 0 °
2h
-30 °
For
Ph e
Cae
-60 °
Ph e
Ho r
Car 8 h
-6 0 °
-6 0°
Hyi
Dor
4h
Re-6
t 0°
2h
-60 °
V ol
Mus
Men
Aps
Hyi
Cha
Oct
Chapter 2
Constellations
Scl
2h
VVelol
Cru
And
T ri2 h
3 04°h
30 °
4h
0°
Lep
Mus
1 4h
6h
0°
CMa
1 0h
A nt -3 0 °HyaPyx
12h
Cru Cen
-60 °
And
T ri2 h
4h
6h
30°
Psc
Ori
CMi
1 0h
Se x0 °
12h
-30 °
Per
Psc
8h
0°
12h
0°
Nor
Nor
20 h
1 4h
Cen
-3 0
°
Tau
Per
Aur
Cnc
Hya
1Crv
2h
-30 °
2 h Cas
60°
CMi
Sco
Mic
Ind
T uc
Sgr
2 h4 h Cas
6 06°0 °
Gem
Crt
PsA
30°
Cnc
12h
0°
1 4h
0°
Vir
6h
8 h30 °
Gem
3 0°
Leo
20 h
0°
A qr
8h
1 0h 3 0 °
Leo
Del Sg e
Eq u
LMi
1 0h
3 0°
12h
30°
Lyn
Orient to
Orion
Aur
Com
Sg e
6h
4h
60
6 0 °°
UMa
LMi
Lyr
20 h Lyr
2030
h°
V ul
22h
2 2 h3 0 °
8 h6h
6 060
° °
Lyn
Summer Triangle
Region
Cyg
1 0h 8 h
6 0° 6 0 °
1 0h
6 0°
UMa
Lac Lac
Cam
Cam
11
22
23
Orient to Orion
1 Find Orion and note his stars
2 Follow OrionÕs belt south to
Canis Major, his large dog
Betelgeuse
Orion
Sirius
Rigel
Canis Major
3 Slide along OrionÕs Collar Bone
to Canis Minor, the smaller dog
4 Go Diagonally up Orion to the
Dancing Twins, Gemini
Castor
Gemini
Pollux
Canis Minor
Procyon
5 Go Straight up
OrionÕs B ody
to reach Auriga,
the Charioteer
Auriga Capella
6 Going West Along
OrionÕs B elt R eveals
Taurus
Taurus
Pleiades
star cluster
Aldebaran
Chapter 2
Constellations
12
23
24
7 Little Lepus Hides b eneath OrionÕs F eet
8 Questioning Leo follows Gemini
Leo
Lepus the Hare
9 Crabby Cancer lies between
Pollux and Leo
10 Monoceros, the secretive Unicorn
slinks behind Orion
Cancer the Crab
Monoceros
11 Perseus treds
on T aurusÕ H orn
Perseus
Chapter 2
Constellations
13
24
25
Arc to Arcturus
1 Find Big Dipper part of Ursa Major
2 Extend the curve of the Handle to
ARCTURUS , the first bright star
Big Dipper,
part of Ursa Major
Arc to Arcturus
..
3 Draw in Bootes, the Herdsman
Shaped like a Kite
4 Continue the Curve through Arcturus,
but straighten to
Speed to Spica
..
Bootes
Spica
Chapter 2
Constellations
14
25
26
5 Fill in Virgo, lying on her back
..
6 Corona Borealis Nestles Near Bootes
Corona
Borealis
Virgo
7 Leo lies above VirgoÕs Head
8 Scorpius and Libra lie below VirgoÕs Legs
Leo
Libra
Scorpius
Chapter 2
Constellations
15
26
27
Summer Triangle Region
2 Deneb is the tail of
Cygnus the Swan
1 Summer Triangle joins
stars from three constellations
Deneb
Vega
CygnusÕ head is in
the middle of the triangle
Altair
D
e
n
e
b
A
l
t
a
i
r
D
e
n
e
b
V
e
g
a
3 Altair is in Aquila the Eagle
A
l
t
a
i
r
V goes to C
y
e
g
g
n
a
u
s
4 Vega,brightest star in the triangle
is part of Lyra, the lyre
Aquila
D
e
n
e
b
A
l
t
a
i
r
Chapter 2
V goes to C
y
e
g
g
n
a
u
s
A L
q
u
i
l
a
Constellations
D
e
n
e
b
A
l
t
a
i
r
V goes to C
e
y
g
g
a
n
u
s
A
q
u
i
l
a
L
y
r
a
16
27
28
6 Libra, the scales stands where
ScorpiusÕ claws once were
5 ScorpiusÕ tail scoops south
of the Summer Triangle
Arcturus
Find Libra
on a line from
Antares to
Spica or Arcturus
Libra
Spica
Antares
Antares
Scorpius
the Scorpion
7 Sagittarius the Archer
follows ScorpiusÕ Tail
Sagittarius can
look like a teapot
Chapter 2
8 Sagittarius the Archer
is Supposed to be a Centaur
Sagittarius
Constellations
17
28
29
Chapter 2
Constellations
18
30
Chapter 2
Constellations
19