Unit 7 : Latitude : Longitude : Directions : Unit Questionnaire

Unit 1: How to Point to a Star
Unit 2: Where on Earth Are You?
Unit 3: Earth's Rotation and the Sun's Apparent Motion
Unit 4: Yearly Changes in the Sky
Unit 5: Seasons and Climate
Unit 6: Sundials
Unit 7: Navigation
Unit 8: Ancient Astronomy
Unit 9: Constellations


Figuring out what direction to travel to arrive at your destination

You can use any celestial object to determine direction, but in many cases the problem gets complicated (due to spherical trigonometry). However, there are two simple methods that require no math.

1. Use the Pole Star to show you where north lies. This was used by the Vikings when navigating in the north Atlantic and works anywhere in the Northern Hemisphere.  The Pole Star does get harder to see as you get close to the equator.  The reason for this is that the Pole Star gets closer to the horizon.

2 Use a star compass.  This method works best if you are on or near Earth's equator. At the equator, the azimuth at which a star will rise or set is related to its declination in a very simple way, as the diagram below shows.

The South Pacific islanders memorized which stars' rising or setting direction would lead them on the correct path from one island to another.

Having some trouble with the idea of a Star Compass?  Brisban can point you in the right direction.  Click on his icon to the left for No Frill's Help.


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