• As early as 5000 years ago, people began naming patterns of stars, called constellations, in the honor of mythological characters or great heroes.

• Today, 88 constellations are recognized.• They divide the sky into disjoint units. • Every star in the sky is in one of these

constellations.

• Astronomers label stars within a constellation based on their apparent brightness, – brightest = alpha a, – second brightest = beta b,– …

• Some of the brightest stars have actual names, like Rigel & Betelgeuse (both in the constellation Orion)

Ursa Major

Ursa Major, the Great Bear, is visible in the Northern Hemisphere all year long.

Ursa MajorCircumpolar Constellation

How to find Pole Star

Ursa Minor• Ursa Minor, the

Little Bear, is visible in the Northern Hemisphere all year long.

• Ursa Minor is mostly known for Polaris, the North Star, which may be found at the end of the handle.

Ursa MinorCircumpolar Constellation

Saharan Starry Night 

Views of Orion from Tasmania (Australia) and Iran (Asia)

Cepheus• The story behind it:

– Cepheus was the King of Ethiopia. He married Cassiopeia and they had a daughter Andromeda. Cassiopeia was incredibly beautiful but immensely vain. She was also proud of her daughter's beauty. In fact she continually boasted that the two of them were more beautiful than any of the fifty sea nymphs who attended Poseidon's court.

– These nymphs (the Nereids) complained to Poseidon, who felt he had to defend his own reputation. So he sent a flood to devastate Cepheus' kingdom. The oracles told Cepheus that in order to save his people he must sacrifice his daughter to a great sea monster: Andromeda was tied to a rock along the coastline, dressed only in her jewelry. The monster would be along in due time to take his prize.

– At that moment Perseus came flying by. He had just killed the Gorgon Medusa and was carrying the severed head back to Athene. To make a long story short, he saved her then turned everyone into stone by showing them the severed head.

– Poseidon then put the stone frozen Cepheus and Cassiopeia into the heavens, but with a twist: he made the vain Cassiopeia spin around on her chair, spending half the year upside down. As for Cepheus, Poseidon gave him a number of medium sized stars that go to make his square face with a pointed crown.

CepheusCircumpolar Constellation

CassiopeiaCircumpolar Constellation

Draco• Draco, the

Dragon, used to hold special significance as the location of the pole star, but due to the Earth's precession, the pole has shifted to Polaris in Ursa Minor.

Circumpolar Constellations

Circumpolar Constellations

Circumpolar Constellations

Circumpolar Constellations

Circumpolar Constellations

Circumpolar Constellations

Orion• Orion is the master of the winter skies. He lords over

the heavens from late fall to early spring, with his hunting dog Sirius trailing at his feet.

• The story behind it: (Orion holding an animal)– Orion was known as the "dweller of the mountain",

and was famous for his prowess both as a hunter and as a lover. But when he boasted that he would eventually rid the earth of all the wild animals, his doom may have been sealed. The Earth Goddess sent the deadly scorpion to Orion to kill him. Orion engaged the scorpion in battle but quickly realized its armour was impervious to any mortal's attack. Orion then jumped into the sea and died. In his eternal hunting, Orion is careful to keep well ahead of the scorpion. Orion disappears over the horizon by the time Scorpio rises in the east, as it becomes his turn to rule the evening sky.

Orion Not a circumpolar constellation, but a seasonal constellationBetelgeuse, the right arm of Orion (or "armpit" as the name suggests), glows with a dull red. Rigel, in the opposite corner of the constellation, is blue and much brighter.

• Orion

• On the left: The Hunter - Orion• In the middle: Name: The Bull - Taurus • On the right: Name: The Greater Dog - Canis Major

• On the left: The Lion - Leo • In the middle: The Herdsman - Böötes • On the right: The Virgin - Virgo

• On the left: The Crab - Cancer • In the middle: The Scorpion - Scorpio • On the right: The Archer - Sagittarius

• On the left and in the middle: Andromeda – The Andromeda constellation is famous for containing the

Andromeda Nebula, the closest galaxy to our Milky Way. • On the right: The Fishes, Pisces

Ecliptic Constellations & Zodiac Signs

• A band of 12 constellations around the sky entered on the ecliptic (apparent path of the sun on the earth as the earth revolves around it).

• Aries, Leo, Sagittarius, Taurus, Virgo, Capricorn, Gemini, Libra, Aquarius, Cancer, Scorpio, and Pisces.

Ecliptic Constellations

Hindu Calendar Rashi

The Constellations, using H. A. Rey's Scheme

Andromeda Antlia Apus AquariusAquila Ara Aries AurigaBoötes Caelum Camelopardalis CancerCanes Venatici Canis Major Canis Minor CapricornusCarina Cassiopeia Centaurus CepheusCetus Chamaeleon Circinus ColumbaComa Berenices Corona Australis Corona Borealis CorvusCrater Crux Cygnus DelphinusDorado Draco Equuleus EridanusFornax Gemini Grus HerculesHorologium Hydra Hydrus IndusLacerta Leo Leo Minor LepusLibra Lupus Lynx LyraMensa Microscopium Monoceros MuscaNorma Octans Ophiuchus OrionPavo Pegasus Perseus PhoenixPictor Pisces Piscis Austrinus PuppisPyxis Reticulum Sagitta SagittariusScorpius Sculptor Scutum SerpensSextans Taurus Telescopium TriangulumTriangulum Australe Tucana Ursa Major Ursa MinorVela Virgo Volans Vulpecula

http://www.enchantedlearning.com/subjects/astronomy/stars/bright.shtml

Brightest Stars and Their Constellations

http://www.astro.wisc.edu/~dolan/constellations/extra/brightest.html

The Dome of the Sky:Definitions in your local sky

Angular size of moon ~ ½ o

Angular distance between the “pointer stars” ~ 5o

To Polaris

Latitude and Longitude

Beavercreek, OHLatitude: 39.73 N, Longitude: 84.06 W

Different sets of constellations are visible in northern and southern skies.

The Altitude of the celestial pole (Polaris) = your latitude

Counter-Clockwise Rotation

Clockwise Rotation

Northern Hemisphere Southern Hemisphere

The Altitude of the celestial pole (Polaris) = your latitude

Right Ascension and Declination

• Right Ascension (RA): Analogous to longitude, but on the celestial sphere.– It is the east-west angle between the

vernal equinox and a location on the celestial sphere.

• Declination (dec): Analogous to latitude, but on the celestial sphere.– It is the north-south angle between the

celestial equator and a location on the celestial sphere.

Units of R.A.

360o = 24h

15o/h

Azimuth and Altitude are observer centric.