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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
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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
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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
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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
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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
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20 21
Figure 2-7 Constellations of the Zodiac, the Constellations Along the Ecliptic
Chapter 2
Constellations
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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
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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
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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
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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
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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
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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
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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
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28 29
Chapter 2
Constellations
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30
Chapter 2
Constellations
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