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Celestial Navigation Tools

Celestial navigation tools were first used when people began taking to the sea for purposes of exploration. Simple and ancient tools such as the back staff or the cross staff were the first to be used for taking celestial measurements. These instruments soon evolved into more complex tools, ranging from the seemingly arcane astrolabe to the modern mariner's sextant. Cultures with a strong understanding of the mathematics behind these devices were the first to successfully circumnavigate the globe.

Simple Navigation Tools
- Among the first simple but inaccurate celestial navigational tools was the cross staff. The cross staff was a long wooden staff with a marked series of measurements based on the mathematical principle of trigonometry used to determine the angle of the horizon to various celestial objects for the purpose of determining location. Unfortunately the cross staff had the major drawback of being rather inaccurate on choppy seas and required a good bit of training to read accurately. The back staff was a modification of the cross staff, developed in 1594 by John Davis, an English sea captain. The back staff addressed some key flaws of its predecessor, such as lessening the need for a correct posture while holding the device, lessening the impact of sun glare for daytime readings as well as an overall reduced size , making it more practical for use on the sea.
Complex Navigation Tools
- In an effort to improve the effectiveness and accessibility of mechanical navigational equipment, ventures of the era gave birth to several devices intended for celestial navigation like the mariner's quadrant, the mariner's astrolabe, and a device known as the nocturnal. In ancient terminology the astrolabe was a chemically-assisted calculation machine, with versions existing not only for navigation but for a host of other competition purposes. In terms of a navigational device, the astrolabe was used to determine latitude by gauging the angle of the noon-hour sun. The nocturnal was used to determine location with the star Polaris as a point of reference, working in a similar way to that of the mariner;s astrolabe. These complex navigational tools required a high degree of expertise and training, turning navigation into a lucrative trade.
The Modern Sextant
- The modern distillation of the numerous navigation machines is the sextant. This tool makes measuring the angle between two objects a simple task that can be undertaken by virtually anyone with a minimal amount of training. The use of a sliding ruler makes accurate measurements of the angle between objects far easier than that of older devices, as the design combines the most effective elements of several of the preceding tools into a single unit.

Astronomy