Download Constellation Notes

Constellations
Grade 5 Science
What is a constellation?
A constellation is a group of visible starts that form a pattern when viewed from the Earth.
The pattern they form may take the shape of an animal, a mythological creature, a man, a
woman, or an inanimate object such as a microscope, a compass, or a crown.
How many constellations are there?
The sky was divided up into 88 different constellations in 1922. This included 48 ancient
constellations listed by the Greek astronomer Ptolemy as well as 40 new constellations.
Star Maps
The 88 different constellations divide up the entire night sky as seen from all around the
Earth. Star maps are made of the brightest stars and the patterns that they make which
give rise to the names of the constellations. The maps of the stars represents the position
of the stars as we see them from Earth. The stars in each constellation may not be close
to each other at all. Some of them are bright because they are close to the Earth while
others are bright because they are very large stars
Hemisphere and Seasons
Not all of the constellations are visible from any one point on Earth. Star maps typically
divide into maps for the northern hemisphere and southern hemisphere. The season of
the year can also affect what constellations are visible from where you are located on
Earth.
Uses for the Constellations
Constellations are useful because they can help people to recognize stars in the sky. By
looking for patterns, the stars and locations can be much easier to spot. The
constellations had uses in ancient times. They were used to help keep track of the
calendar, this was important for planting and harvesting crops.
Another important use for constellations was for navigation. By finding Ursa Minor it is
fairly easy to spot the North Star (Polaris). Using the height of the North Star in the sky,
navigators could figure out their latitude helping ships to travel across the oceans.
Stars Colors:
A star’s color is critical in identifying the star, because it tells us the star’s surface
temperature in the black body radiation scale. The sun has a surface temperature of
5,500 K, typical for a yellow star. Red stars are cooler than the sun, with a surface
temperature of 3,500 K for a bright red star and 2,500 K for a dark red star. The hottest
stars are blue, with their surface temperatures falling anywhere between 10,000 K and
50,000 K.
Stars begin as a mass of dust and gas dense enough to start collapsing inwards under the
pressure of its own gravity. A star does no stay the same color throughout its lifecycle.
Star are classed in order of decreasing hydrogen absorption strength:
Class
O
B
A
F
G
K
M
Color
Blue
Blue white
White to blue white
White
Yellowish white
Yellow orange
Orange red
Blue stars are brighter than white or red stars because they are larger, therefore burn
much faster and hotter then less massive stars. Approximately 88% of stars in the
universe seem to be the cooler type K and M.
Interesting Fact about Constellations





the largest constellation by area is Hydra which is 3.16% of the sky
the smallest is Crux which only takes up 0.17% of the sky
small patterns of stars within a constellation are called asterisms. These include
the Big Dipper and Little Dipper
the word “constellation” comes from a Latin term meaning “set with stars”
twenty two different constellation names start with the letter “C”
image © NASA