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

• Some of the brightest Some of the brightest stars have actual stars have actual names, like names, like RigelRigel & & BetelgeuseBetelgeuse (both in the (both in the constellation constellation OrionOrion))

Ursa MajorUrsa Major

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

Ursa MajorUrsa MajorCircumpolar ConstellationCircumpolar Constellation

How to find Pole StarHow to find Pole Star

Ursa MinorUrsa 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 MinorUrsa MinorCircumpolar ConstellationCircumpolar Constellation

Saharan Starry Night 

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

CepheusCepheus• 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.

CepheusCepheusCircumpolar ConstellationCircumpolar Constellation

CassiopeiaCassiopeiaCircumpolar ConstellationCircumpolar Constellation

DracoDraco

• 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

OrionOrion• 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 constellation

BetelgeuseBetelgeuse,, the right arm of Orion (or "armpit" as the name suggests), glows with a dull red. Rigel,Rigel, in the opposite corner of the constellation, is blue and much brighter.

• Orion

•On the left: On the left: The Hunter - OrionThe Hunter - Orion•In the middle: Name: In the middle: Name: The Bull - Taurus The Bull - Taurus •On the right: Name: On the right: Name: The Greater Dog - Canis MajorThe 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 & Ecliptic Constellations & Zodiac SignsZodiac 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 ConstellationsEcliptic Constellations

Hindu Calendar Rashi

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

Andromeda Antlia Apus Aquarius

Aquila Ara Aries Auriga

Boötes Caelum Camelopardalis Cancer

Canes Venatici Canis Major Canis Minor Capricornus

Carina Cassiopeia Centaurus Cepheus

Cetus Chamaeleon Circinus Columba

Coma Berenices Corona Australis Corona Borealis Corvus

Crater Crux Cygnus Delphinus

Dorado Draco Equuleus Eridanus

Fornax Gemini Grus Hercules

Horologium Hydra Hydrus Indus

Lacerta Leo Leo Minor Lepus

Libra Lupus Lynx Lyra

Mensa Microscopium Monoceros Musca

Norma Octans Ophiuchus Orion

Pavo Pegasus Perseus Phoenix

Pictor Pisces Piscis Austrinus Puppis

Pyxis Reticulum Sagitta Sagittarius

Scorpius Sculptor Scutum Serpens

Sextans Taurus Telescopium Triangulum

Triangulum Australe Tucana Ursa Major Ursa Minor

Vela Virgo Volans Vulpecula

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

Brightest Stars Brightest Stars and Their Constellationsand 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.