Constellations pg. 617-618

What is a constellation?

How many constellations can be seen from Earth’s northern and southern hemispheres?

True or False: Constellations are human inventions.

What is an asterim?

What causes the apparent movement of constellations across Earth’s sky?

How many stars are visible in the night sky?

about 6000 visible stars

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

imaginary bubble that surrounds Earth onto which all the stars are positioned

like Earth, the Celestial sphere has a “North Pole,” “South Pole,” and an equator

You may have noticed that the Celestial Sphere seems to be tipped over.

It is actually Earth that is at an angle (tipped over at an angle of 23.5 degrees!)

This tilt is at an angle in relation to the position of the sun.

The Celestial Sphere

Celestial Portraits

Human brains naturally create patterns

What do you see when you look at the clouds?

The ancients did the same when they looked up at the sky

Do you see a pattern in

these stars?

Constellations

• A name given to a group of stars• Named after heroes, animals, monsters,

objects.• A human invention (not a natural grouping)

Asterisms• Small group of stars that is part

of a larger constellation

• Example– The Big Dipper is

part of the larger constellation Ursa Major

The Big Bear

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

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.

“Quia-less” Quiz!

1. A constellation is a. the same as an asterim

b. a unit of distance

c. a group of stars that form a pattern

2. True or False: The Celestial Sphere is an actual bubble that surrounds Earth and shows the position of stars.

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

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

DEC (declination) is similar to latitude on Earth.

DEC is measured from the celestial equator in degrees.

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 -90

RA (right ascension) is measured in hours, minutes, and seconds, as if we were measuring time instead of position!

RA reads to the EAST.

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)

“Quia-less” Quiz!3. Stars, constellations, planets, can be

found usinga. right ascensionb. declinationc. Both of the above choices are used together

to locate stars, constellations, and planets.