Constellations pg # of stars? 2. Maps of sky Declination Right Ascension Earth’s spin 3. Constellations Define Names of key ones Asterisms

There are about 6000 named, visible stars in the sky.

Astronomy: the oldest science ! Aristotelian view Has the earth and sky on fixed spheres The ancients imagined that the Earth was surrounded by a canopy of stars

The Celestial Sphere: a globe of the sky! An imaginary bubble that surrounds Earth onto which all the stars are positioned. Like Earth, the Celestial sphere has a “North Pole”, a “South Pole”, and an equator.

To locate a place on the surface of the earth we use coordinates. What is the location of Chicago? Shuffle the deck and have sum fun

Stars, constellations, planets, can be found using the coordinates of declination and right ascension on the celestial sphere. Locate Cygnus the Swan (looks like a cross)

DEC (declination) DEC is measured from the celestial equator in degrees (similar to __________). Measurement to the NORTH is positive. The celestial North Pole is at +90 degrees DEC. Measurement to the South is negative. The South Celestial Pole is at _______degrees DEC

RA (right ascension) is similar to _______ is measured in hours, minutes, and seconds, as if we were measuring time instead of position! 0-24 hrs RA reads to the EAST. Astronomers decided to begin RA at the point where the path of the ecliptic crosses the celestial equator: the first day of SPRING. (vernal equinox)

We see a “flat” image of the stars in the constellations, but the stars are actually located at varying distances from earth.

Is the Celestial Sphere tipped over?

Is the Celestial sphere tipped over? It is actually Earth that is at an angle (tipped over at an angle of 23.5° Ecliptic: the path of the sun through the sky

Circumpolar Constellations

Why did the North Star Change? Precession The Earth is not a perfect circle so it does not have a perfect rotational spin. It “wobbles” like a top. So, Polaris has not always been the “North” Star.

Has Polaris always been our North Star?

Celestial Portraits Human brains naturally create patterns. Human brains naturally create patterns. What do you see when you look at the clouds? What do you see when you look at the clouds? The ancients did the same when they looked up at the sky. The ancients did the same when they looked up at the sky.

Constellations A name given to a group of stars 88 in all What do you notice about the constellations that follow?

Zodiac Constellations The 12 constellations that move through during the year.

Do you see a pattern in these stars?

Cassiopeia

Corona Borealis The Northern Crown

Draco the Dragon

Ursa Minor: Little Dipper The last star in the handle of the Little Dipper is the North Star: Polaris: The North Star h?v=N93WV61ETo8

The Big Bear Can you find the stars of the Big Dipper in the constellation?

Asterisms A named group of stars that are part of a larger constellation Example –The Big Dipper is part of the larger constellation Ursa Major

The “tea pot” asterism in the constellation Sagittarius

You probably noticed Constellations Tell a story Orion was a mythical hero and hunter, and in his amorous pursuit of the Pleiades (the 7 daughters of the giant Atlas), the Gods placed them in the sky. And Orion chases after them in the sky for all eternity. Orion was a mythical hero and hunter, and in his amorous pursuit of the Pleiades (the 7 daughters of the giant Atlas), the Gods placed them in the sky. And Orion chases after them in the sky for all eternity.

Your Turn! Look for a pattern, picture, figure, of an object, person, by connecting the stars. Outline the figure. Name the constellation Create a mythological story to go with your constellation

Constellations pg constellations in all We still use 48 of the ancient ones and have added 40 new ones 28 are in the northern sky, 48 are in the southern, 12 are the zodiac constellations In the Northern Hemisphere their named for mythology In the Southern Hemisphere they have modern names