LESSON 11: THE NIGHT SKYOBJECTIVE: BE ABLE TO IDENTIFY

CONSTELLATIONS USING A PLANISPHERE

CONSTELLATIONS

• Constellations group of stars that form a pattern in the sky

• There are 88 accepted constellations listed by the International Astronomical Union (IAU)

• During ancient times, constellations were used for navigation and to tell stories.

WHAT DO YOU SEE?

WHAT THE ANCIENTS SAW

WHAT DO YOU SEE?

WHAT THE ANCIENTS SAW

•The body and tail of the Great Bear make up what is known as the Big Dipper.

STARS PIVOT AROUND A POINT

THE NORTH CELESTIAL POLE (NCP)

• Special spot on the sky that the Earth’s rotation axis points to

• Why special?

During the night the stars appear to rotate around this spot

• Also special (and useful) in other ways …

WATCHING STARS FROM THE NORTH POLE

CONSTELLATIONS ARE BIG

FINDING POLARIS

LUCKY BREAKS!

• The star Polaris is amazing close to NCP (now)

• The “pointer stars” in the Big Dipper line up directly with Polaris!!!!

• Big Dipper is circumpolar constellation

• See it all night and all year• Polaris also called Pole Star, North Star

BIG DIPPER

ZENITH

• the point in the sky or celestial sphere directly above an observer

WHY CARE ABOUT FINDING POLARIS?

• The direction of Polaris is due North

• The angle between Polaris and the horizon is YOUR LATITUDE• How can I measure angles?

BIG DIPPER AS STAR GUIDE

CONSTELLATION FACTS

• Group of stars all in roughly the same direction from Earth, BUT …. Each has its own different distance from the Earth

• Therefore, NOT grouped together is space

• From Greek astronomers have inherited the names of the constellations: mythological figures or animals

• Different cultures on Earth each have different names for the constellations

CONSTELLATION STARS AT DIFFERENTDISTANCES FROM EARTH

VISIBLE CONSTELLATIONS CHANGE OVER A YEAR

• May have heard …

• “Orion is a winter constellation”

• “You can see Cygnus most of the summer”

• Above comments arise because you cannot see the Constellations near where the Sun is in the sky

• Sun so bright it washes out rest of stars

• Since Sun moves along the Ecliptic over a year the constellations “away” from the Sun change over a year.

CONSTELLATIONS ON OPPOSITE SIDE OF SUN (OPPOSITION)

THE ZODIAC

• Band of constellations closest to the Ecliptic (Sun’s yearly path across the sky)

• Correspond to Horoscope “Signs”

• Astrology used to make predictions (not science!)

• Useful for backyard astronomy: Planets and the Moon can always be found in the Zodiac

• Width of the Zodiac belt ~ 18°

Mercury

MarsSaturn

PLANISPHERE

• You are going to make your own planisphere

• This planisphere is made specifically for Reno.

• Answer the questions on the following slide

• How do I find the horizon on the planisphere?

• What is the zenith?

• How do I find the zenith on the planisphere?

• Where does the handle of the Big Dipper point during November 5th at 10 PM?

• Where does the cup of the Big Dipper point during November 5th at 10 PM?

• Which constellation is at the zenith in December 24th?

• Which constellation is near the horizon January 30th?

• During which month is Cepheus on the northern horizon?

• Which way does the cup of the Big Dipper point on April 1?

• Which way does the handle of the Big Dipper point during April 1?

• Which constellations can you see in winter that you can not see in the summer? Which can you see in the summer?

• Which constellations can you see year round?

• Pick a time of year and create your own constellation. Draw the group of stars, draw what it looks like, and name it.