Hack 16. Know Your Constellations Although stars are important, constellations place those stars in context: constellations are the things you can find in the sky most quickly. And once you've found the constellation that's your point of reference, you can go on to find what you're really looking for. The first step in learning the night sky is to know the constellations. Before you attempt to identify constellations in the night sky, you should know the names of the constellations you are looking for and how to pronounce those names. There are 88 official constellations. Fortunately, you can learn them in groups because only some of them are visible, according to your latitude and the time of year. | The best way to learn the constellations is to buy a planisphere [Hack #6], which allows you to dial in the date and see an accurate representation of the night sky for that date. Alternatively, the monthly sky charts in Astronomy and Sky & Telescope magazines provide similar whole sky views for the current month. |
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Table 2-4 lists all 88 modern constellations, including the following data:
Name The official name of the constellation, as assigned by the International Astronomical Union (IAU), the only body authorized legally to name celestial objects.
Pronunciation The pronunciations shown are those commonly used by amateur astronomers. Although many are incorrect, these pronunciations are used so commonly that there is little point in attempting to correct them. For example, Orion is correctly pronounced oh-REE-un rather than oh-RYE-un, and Virgo is WIR-goh rather than VUR-goh, but saying oh-REE-un or WIR-goh will draw strange looks from your observing buddies.
Abbr The official International Astronomical Union (IAU) abbreviation for the constellation name.
Genitive The Latin genitive case is used to indicate possession of or membership in. In astronomy, the genitive form of the constellation name is used to indicate an object's membership in a constellation. For example, the name sigma Orionis (s-Ori) indicates a star designated sigma that belongs to the constellation Orion [Hack #15].
Dec The Dec (Declination) of a constellation determines whether you can see all or part of that constellation from your latitude. If you are north of the equator, subtract 90 from your latitude to determine the most southerly object you can observe. For example, our home is at about 36. 2°N latitude. Subtracting 90° from that gives -53.8°, which is the declination of the most southerly object we can see from our home. The star Canopus, alpha Carinae (a-Car), for example, has declination of -52.7°, which means that it never rises more than about 1.1° above our southern horizon. If you are south of the equator, add 90 to your latitude to determine the most northerly object you can observe. For example, if you are located at 36.2°S latitude (-36.2°), the most northerly object you can observe has a declination of (-36.2° + 90°), or +53.8°. If you are on the equator, at latitude 0°, you can observe any object from declination -90° to +90°, but very northerly and very southerly objects never rise far above your horizon. For example, Polaris (declination +89.25°) never rises higher than 0.75° above your northern horizon.
Season Constellations are divided by season according to their Right Ascension (RA). A constellation that lies wholly or mostly within the RA range 03: 00 to 09:00 is a Winter constellation; 09:00 to 15:00 is Spring; 15:00 to 21:00 is Summer; and 21:00 to 03:00 is Autumn. The season designation is rather arbitrary, but indicates when the constellation is best placed for viewing during evening hours. For example, Orion, a Winter constellation, can be seen as early as mid Summer, when it rises before dawn, and as late as early Spring, when it sets soon after the Sun. Table 2-4. The 88 modern constellationsName | Pronunciation | Abbr | Genitive | Dec (°) | Season |
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Andromeda | an-DROM-eh-duh | And | Andromedae | +21 to +53 | Autumn | Antlia | ANT-lee-uh | Ant | Antliae | -24 to -40 | Spring | Apus | A-pus | Aps | Apodis | -67 to -83 | Summer | Aquarius | a-KWAIR-ee-us | Aqr | Aquarii | +3 to -24 | Autumn | Aquila | AK-will-uh | Aql | Aquilae | +10 to -10 | Summer | Ara | AIR-uh | Ara | Arae | -55 to -68 | Summer | Aries | AIR-eez | Ari | Arietis | +10 to +30 | Autumn | Auriga | uh-RYE-guh | Aur | Aurigae | +28 to +55 | Winter | Bootes | bow-OAT-eez | Boo | Bootis | +8 to +55 | Spring | Caelum | kye-ELL-um | Cae | Caeli | -27 to -49 | Winter | Camelopardalis | CAM-eh-low-PAR-duh-lis | Cam | Camelopardalis | +52 to +87 | Winter | Cancer | CAN-sur | Cnc | Cancri | +7 to +33 | Winter | Canes Venatici | CAWN-es ven-AT-ih-see | CVn | Canum Venaticorum | +28 to +53 | Spring | Canis Major | CAWN-is MAY-jur | CMa | Canis Majoris | -11 to -33 | Winter | | Canis Minor | CAWN-is MYE-nur | CMi | Canis Minoris | 0 to +12 | Winter | Capricornus | CAP-rih-CORN-us | Cap | Capricorni | -9 to 27 | Autumn | Carina | cuh-REE-na | Car | Carinae | -51 to -75 | Winter | Cassiopeia | cass-ee-oh-PEE-uh | Cas | Cassiopeiae | +50 to +60 | Autumn | Centaurus | sen-TAWR-us | Cen | Centauri | -30 to -65 | Spring | Cepheus | SEE-fee-us | Cep | Cephei | +53 to +87 | Autumn | Cetus | SEE-tus | Cet | Ceti | +10 to -25 | Autumn | Chamaeleon | kuh-MEEL-yun | Cha | Chamaeleontis | -74 to -83 | Spring | Circinus | sur-KEE-nus | Cir | Circini | -54 to -70 | Spring | Columba | kuh-LUM-ba | Col | Columbae | -27 to -43 | Winter | Coma Berenices | KOE-muh BAIR-uh-NEES-us | Com | Comae Berenices | +14 to +34 | Spring | Corona Australis | kuh-ROE-nuh aw-STRAWL-is | CrA | Coronae Austri nae | -37 to -45 | Summer | Corona Borealis | kuh-ROE-nuh BOR-ee-AL-us | CrB | Coronae Borealis | +26 to +40 | Summer | Corvus | KOR-vus | Crv | Corvi | -11 to -25 | Spring | Crater | KRATE-ur | Crt | Crateris | -6 to -25 | Spring | Crux | KRUX | Cru | Crucis | -56 to -65 | Spring | Cygnus | SIG-nus | Cyg | Cygni | +28 to +60 | Summer | Delphinus | del-FEE-nus | Del | Delphini | +2 to +21 | Summer | Dorado | dor-AW-doe | Dor | Doradus | -49 to -85 | Winter | Draco | DRAY-koe | Dra | Draconis | +50 to +80 | Summer | Equuleus | eh-KWUH-lee-us | Equ | Equulei | +2 to +13 | Autumn | Eridanus | air-uh-DAHN-us | Eri | Eridani | 0 to -58 | Winter | Fornax | FOR-nacks | For | Fornacis | -24 to -40 | Autumn | Gemini | JEM-ih-nye | Gem | Geminorum | +10 to +35 | Winter | Grus | GROOSE | Gru | Gruis | -37 to -57 | Autumn | Hercules | HUR-cue-leez | Her | Herculis | +4 to +50 | Summer | Horologium | hor-oh-LOGE-ee-um | Hor | Horologii | -40 to -67 | Winter | Hydra | HYE-druh | Hya | Hydrae | -22 to -65 | Spring | Hydrus | HYE-drus | Hyi | Hydri | -58 to -90 | Autumn | Indus | IN-dus | Ind | Indi | -45 to -75 | Autumn | Lacerta | lay-CERT-uh | Lac | Lacertae | +33 to +57 | Autumn | Leo | LEE-oh | Leo | Leonis | -6 to +33 | Spring | Leo Minor | LEE-oh MYE-nur | LMi | Leonis Minoris | +23 to +42 | Spring | Lepus | LEE-pus | Lep | Leporis | -11 to -27 | Winter | Libra | LEE-bruh | Lib | Librae | 0 to -30 | Summer | Lupus | LOO-pus | Lup | Lupi | -30 to -55 | Summer | Lynx | LINKS | Lyn | Lyncis | +34 to +62 | Winter | Lyra | LEER-uh | Lyr | Lyrae | +26 to +48 | Summer | Mensa | MENS-uh | Men | Mensae | -70 to -85 | Winter | Microscopium | mike-roh-SCOPE-ee-um | Mic | Microscopii | -28 to -45 | Autumn | Monoceros | MON-oh-SAIR-ose | Mon | Monocerotis | -11 to +12 | Winter | Musca | MUSS-kuh | Mus | Muscae | -64 to -74 | Spring | Norma | NOR-muh | Nor | Normae | -42 to -60 | Summer | Octans | OCT-anz | Oct | Octantis | -75 to -90 | Summer | Ophiuchus | oh-FEE-uh-kuss | Oph | Ophiuchi | +14 to -30 | Summer | Orion | oh-RYE-un | Ori | Orionis | +8 to +23 | Winter | Pavo | PAW-voh | Pav | Pavonis | -57 to -75 | Summer | Pegasus | PEG-uh-sus | Peg | Pegasi | +2 to +37 | Autumn | Perseus | PERS-ee-us | Per | Persei | +31 to +59 | Winter | Phoenix | FEE-nicks | Phe | Phoenicis | -40 to -59 | Autumn | Pictor | PIK-tor | Pic | Pictoris | -43 to -64 | Winter | Pisces | PYE-seez | Psc | Piscium | -5 to +34 | Autumn | Piscis Austrinus | PYE-see z aw-STRINE-us | PsA | Piscis Austrini | -25 to -36 | Autumn | Puppis | PUPP-is | Pup | Puppis | -12 to -51 | Winter | Pyxis | PICKS-is | Pyx | Pyxidis | -17 to -38 | Spring | Reticulum | reh-TICK-you-lum | Ret | Reticuli | -53 to -67 | Winter | Sagitta | SADJ-ih-taw | Sge | Sagittae | +17 to +22 | Summer | Sagittarius | SADJ-ih-TAIR-ee-us | Sgr | Sagittarii | -12 to -46 | Summer | Scorpius | SKOR-pee-us | Sco | Scorpii | -8 to -45 | Summer | Sculptor | SKULP-tor | Scl | Sculptoris | -25 to -59 | Autumn | Scutum | SKEW-tum | Sct | Scuti | -4 to -16 | Summer | Serpens Caput | SUR-penz KAP-put | Ser | Serpentis | -4 to +20 | Summer | Serpens Cauda | SUR-penz CAW-duh | Ser | Serpentis | -15 to +6 | Summer | Sextans | SEX-tanz | Sex | Sextantis | -11 to +7 | Spring | Taurus | TAWR-us | Tau | Tauri | +10 to +30 | Winter | Telescopium | tell-uh-SCOPE-ee-um | Tel | Telescopii | -46 to -57 | Summer | Triangulum | try-ANG-you-lum | Tri | Trianguli | +26 to +37 | Autumn | Triangulum Australe | try-ANG-you-lum aw-STRAWL-eh | TrA | Trianguli Australis | -60 to -70 | Summer | Tucana | too-CANN-uh | Tuc | Tucana | -56 to -75 | Autumn | Ursa Major | ERS-uh MAY-jur | UMa | Ursae | Majoris | +29 to +73 | Spring | Ursa Minor | ERS-uh MYE-nur | UMi | Ursae Minoris | +66 t +90 | Summer | Vela | VAY-luh | Vel | Velorum | -40 to -57 | Spring | Virgo | VUR-goh | Vir | Virginis | -22 to +15 | Spring | Volans | vohl-LANZ | Vol | Volantis | -64 to -75 | Winter | Vulpecula | vul-PECK-you-luh | Vul | Vulpeculae | +20 to +30 | Summer |
If you counted, you may have noticed that there are 89 constellations listed. That's because Serpens, the Snake, is the only non-contiguous constellation, split in two by Ophiuchus, the Snake Bearer. The more northerly portion is called Serpens Caput, or Head of the Snake. The more southerly is Serpens Cauda, or Tail of the Snake. Officially, these two chunks comprise a single constellation. Both use the same abbreviation and genitive, but most astronomers treat them as separate constellations. |