Objectives: (Can be combined)
—Locate and observe Big Dipper
—Locate and observe North Star
—Locate and observe Little Dipper
—Locate and observe the Dolphin
*Finding the North Star and the Little Dipper are not necessary for finding the Dolphin but can be justified as good practice for finding the more difficult constellation Delphinus.
Teaching Materials:
—Book on celestial navigation. (24]
—Slide Projector
—Screen
—Prepared slides
Actual observations:
—A very clear night is needed to see the complete Dolphin. The North Star and both Dippers are among the easiest celestial observations that can be made. First find the Big Dipper. The way to do this is to know its shape. It will stand out enough for the student to differentiate it from the others.
(figure available in print form)
To find the North Star (Polaris) draw an imaginary line between the two stars in the Big Dipper that are at the farther end of the bowl from the handle. These two stars are often called ‘pointers‘. Draw this imaginary line from the bottom of the cup towards the top of the cup. Extend this line in the same direction, five times the length of the original line. This extension will intersect a fairly bright star, which is Polaris or the North Star. Polaris as the pole star is almost exactly at the North pole; that is why it is called the North Star. In this latitude it is almost halfway up in the sky from the horizon. B facing the Pole star. Polaris, one can determine N.S.E.W. without a compass; right is east, left is west, and behind the observer is south, because the North Star is so near the north pole and the earth rotates around an axis which passes through the north and south poles, the rest of the stars in the sky appear to rotate around the North Star in a counterclockwise direction once each twenty-four hours.
—Once the North Star has been located, the Little Dipper can easily be found because the North Star is the last star in the handle of the Little Dipper.
—The Dolphin. First find the North Star. To the east is the Milky Way bisecting the sky from north to south. The Dolphin is seen clustered on the eastern side of the Milky Way. Remember that as the Earth rotates, the stars will change position in the sky. The Dolphin, although always east of the Milky Way, is not always in the same place in the sky.
—The Dolphin has five brighter stars and five point stars. The constellation is visible because its stars are densely packed together and form a distinct shape.
(figure available in print form)
