The Changing Night Sky

  • At any location on Earth, the altitude of the NCP equals the latitude.

  • Ithaca is located at 42 degrees North latitude, so as seen in Ithaca, the altitude of the North Celestial Pole (NCP) is 42 degrees.

  • Through the night, a star moves across the sky as the Earth rotates.

  • Like the Sun, stars rise in the east and set in the west.

  • The path that the Sun follows changes from day to day because of the Earth's tilt on its axis.

  • The path a star follows along the celestial sphere is parallel to the celestial equator, and north or south of the equator according to its declination.

  • As seen in Ithaca, some of the stars close to the North Celestial Pole never set. Their paths are always above our horizon; we call them circumpolar stars.

Can you describe the paths of stars at the Equator and at the North Pole? Click here for the answer.

What about in Hawaii? Click here for the answer.

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