1. Notepack 28 Aim: How do the stars help us?
Do Now: What is the scientific name of the North Star? Where is it located?

2. The Importance of Stars
Before their was electricity, the moon and the stars were all that would illuminant the night sky.
Although most of the stars are still in the sky, most people cannot see them due to the ambient light reflected from buildings, street lights and cars.
People that live in the city see fewer stars in the sky than people who live in the suburbs or mountains.

5. http://www. shutterstock

6. The Importance of Stars (cont)
Ancient people used to look up into the night sky and would imagine seeing pictures among the stars. (constellations)

7. Constellations
Constellations are a group of stars that appear to form an image if the stars were connected by lines.
Constellations move across the sky, from East to West (just like the motion of the Sun) and they appear and disappear through the year.

8. Constellations (cont)
In the past, farmers would use the constellations to help them predict when it was a good time to plant and harvest their crops.
Farmers would notice that the appearance of certain constellations meant that it was a good time to plant their crops; while the appearance of another constellation meant it was time to harvest them.

9. Important constellations for this class
The Big Dipper
Is supposed to look like a Bear.
It is found in the northern hemisphere.
It is important because we can use it to find the North Star (Polaris)

10. Important constellations for this class
Orion
Is supposed to look like a Hunter.
It has two of the stars that appear in the reference table.
It is important because it appears on the regents as a reference constellation.

11. Using Stars to Navigate
Before GPS, sailors and travelers would use the stars to help them find their location on a map.
By calculating the altitude of the North Star, a traveler could determine what latitude they were on a map.

12. Polaris – The North Star
The North Star’s real name is Polaris.
Polaris is located directly above the North Pole.
Because Polaris is directly over the North Pole, it does not move across the night sky like the other stars.
All the other stars seem to move around it.
Polaris is always in the same place each night, all year long.

13. How do you find Polaris in the night sky?

14. How do you find Polaris in the night sky?
You can find the North Star by locating the two bowl stars of the Big Dipper.
Follow those stars in a straight line to the first bright star you see. That is Polaris.

15. The Apparent movement of a star
Most stars move across the night sky.
The stars rise from the Eastern Horizon and travel up till they reach their highest point, then they travel down towards the Western Horizon.
This motion is only apparent. That means that the stars are not moving in that manner.
The stars seem to move due to the spinning (rotation) of the Earth on its axis.

16. Video

17. Altitude of a star
The altitude of a star is the angle that a star makes from an observer relative to the ground.
All the stars’ altitudes (except for Polaris), change throughout the night because they are constantly moving across the sky.
Only Polaris remains at a constant altitude.

18. The Zenith
The zenith is an imaginary point in the sky where a star is at its highest point (Altitude)in the sky.
It also means the point directly above an observers head.

19. What is the altitude of this star?
About degrees

20. What is the altitude of this star?
About 40 degrees

21. Altitude of Polaris
Because Polaris is always above the north pole, the altitude of Polaris is always equal to your latitude.
Altitude Polaris=latitude

22. Altitude of Polaris (cont)
However, as a traveler moves from the south to the north, or vice versa, Polaris’ altitude will change. Either rising or lowering.
There is no change if you are moving East to West.

23. Polaris at the Equator

24. Polaris at the NYC

25. Polaris at the North Pole

26. NYC and Rome are located on the same latitude.
Polaris at the NYC
Polaris at the Rome
NYC and Rome are located on the same latitude.
Polaris’ altitude is the same at both places.

27. How the North Star is Viewed from Earth
Polaris moves from being directly overhead (at the North Pole) to sinking down to the horizon (at the Equator).
You cannot see Polaris in the Southern Hemisphere.