Celestial navigation is still to this day a tool used by seamen to check, whithout the need of electrical appliances, their position while out in the ocean. That’s why this is one of my classes in my nautical sciences degree. In this article i won’t go to deep on the calculations themselves, I’ll just talk a little about the class.
Usually we only determine our position based on the sun since the lessons are at 1300 (1 o’clock pm). This observation is quite simple, since all we have to do is measure how high the sun is (from the horizon) and with the help from nautical almanacs we do the math.
This past Monday, May 21st, me and my classmates had lesson at night, which started at 2000, so we could try determine our position from the stars.
Determining how high the stars are was harder for multiple reasons:
• We need to measure the height of three different stars so we can intersect their directions;
• We need to be sure of what star we are measuring so we can later look it up in the nautical almanac;
• Observations can be hampered by meteorology, sometimes even impossible;
• The observation as to take place during twilight, in order to be both dark enough to see the stars and clear enough to see the horizon.
Instruments needed to determine our astronomical position:
• Star finder (used in nocturnal observations):
At first i was certain i would be terrible at this class since when I look up to the stars, they all look alike to me XD. However, thanks to the star finder, which gives the user the bearings (azimuth) and the expected height at which I should be able to find the star, even someone (like me) who can’t find the stars just by relative position in the sky is able to find them. The star finder also indicates which stars are not visible from the observer’s location.
A sextant is the instrument that allows us to take the height, that is, the vertical angular distance between a star and the horizon.
• Nautical almanac and other publications:
This are books that indicate important data for us to be able to complete our calculations, for example, the declination of the Sun on a given day.