The Night Sky

Where are the stars and constellations located?

Draw the earth on it’s axis What is a sphere? What is latitude and longitude Are you good at following directions?

Warm –up

Night Sky BasicsSection 1

The stars and planets appear to be on a large sphere surrounding the earth

NOT TRUE

The celestial sphere

Aligned with earth

Celestial equator along the same line as earth equator

Celestial north pole over north pool of earth

Pittsburgh is 42 degrees lat, by 85 degrees long

Earth Coordinate System vs. The Celestial Coordinate System

Earth Coordinate System

Latitude vs. Longitude

Latitude Longitude

Measures the angle north or south of the equator

0-90 north 0- -90south

Equator is 0 degrees

Measures angle east or west

0-180 East 0-180 West

Prime Meridian is 0

Celestial Sphere Coordinate System

Declination vs. Right Ascension

Declination Right Ascension

Distance measured north/south

0-90 north 0-90 south

Latitude

Distance measured eastward on Celestial Sphere

0-24 hours

Longitude

Zenith: Point that is directly overhead

Celestial Sphere Terminology

The apparent path that the sun takes around the celestial sphere

Ecliptic

The north star Directly overhead Appears not to move

Polaris

The earth slowly wobbles on its axis of rotation.

One wobble takes approximately 26,000 years.

Because of this slow wobble, the stars SLOWLY move in a small circle in the night sky.

Precession

A star is a massive, luminous ball of plasma that is held together by gravity.

Star

Where is polaris? North pole

Equator

Pittsburgh

At zenith

At horizon

42 degrees

THERE IS NOT A SOUTH STAR!

South star

Draw a star

Draw a constellation:

Name a star:

Warm-up

A constellation is an official grouping of stars.

They are usually ancient in origin, and come

from greek mythology

Constellations

an unofficial grouping of stars that make a pattern in the sky.

will usually vary from region to region

Summer Triangle: Vega, Deneb, and Altair, Big dipper

◦ Piece of the constellations Ursa Major◦ In northern Europe, they call a part of ursa major

the “Great plow”. ◦

Asterism

visible all year round It appears to circle the celestial pole.

Circumpolar constellations

Subtract your latitude from 90 ◦ Pittsburgh: 42

◦ Florida: 30

◦ North Pole: 90

◦ Equator: 0

Finding Circumpolar constellations

1. Ursa Major, 2. Ursa Minor, 3. Cassiopea, 4. Cephius, 5. Draco.

Circumpolar constellations in our area

Constellation Names:◦ Latin names. ◦ Most of these names come from Greek

mythology.

Constellation Names and Designations

Star names◦ Arabic names. ◦ Many star names come from Mid-Eastern

mythology.

Stars in constellation are designated by their brightness.

astronomers use greek letters.

The brightest star is designated Alpha, The second brightest is designated Beta, the third brightest is designated Gamma, etc

Star Designations

Ursa Minor

Ursa Minor

Polaris (The North Star)

Ursa Major

Cassiopeia

Polaris (The North Star)

Gemini

Castor Pollux

Orion

Betelgeuse Rigel

Canis Major

Sirius

Canis Minor

Procyon

Taurus

Aldebaran Pleiades

Cygnus

Deneb

Lyra

Vega

Aquila

Altair

Ursa Major In Greek mythology, Zeus (the king of the

gods) lusts after a young woman named Callisto, a nymph of Artemis. Hera, Zeus's wife, transforms Callisto into a bear due to her jealousy of being extremely beautiful. Callisto, while in bear form later encounters her son Arcas. Arcas almost shoots the bear, but to avert the tragedy, Zeus hurls them both into the sky, forming Ursa Major.

Mythology

One story tells that Orion was killed by a giant scorpion; the gods raised him and the Scorpion to the skies,

Orion

Aquila was identified as Αετός Δίας (Aetos Dios), the eagle that carried the thunderbolts of Zeus and was sent by him to carry the shepherd boy Ganymede, whom he desired, to Mount Olympus;

Aquila