Which item is primarily used to measure angles between celestial bodies and the horizon for navigation?

Which item is primarily used to measure angles between celestial bodies and the horizon for navigation?

• A. an instrument used to measure wind speed.
• B. tool that measures angles between celestial bodies and the horizon for accurate navigation.
• C. a device for recording tides.
• D. a tool for plotting nautical charts.

Answer: (B)

In celestial navigation, you determine your position by measuring the altitude of celestial bodies above the horizon. The instrument designed for this purpose is a sextant, which lets you accurately read the angle between the horizon and a celestial body such as the Sun or a star. That single altitude measurement, paired with exact time, lets navigators compute their location on the globe. The other options describe tools for wind speed, tides, or chart plotting, none of which measure the celestial–horizon angle needed for navigation. So the described tool that measures these angles for accurate navigation is the one that fits the purpose.

In celestial navigation, you determine your position by measuring the altitude of celestial bodies above the horizon. The instrument designed for this purpose is a sextant, which lets you accurately read the angle between the horizon and a celestial body such as the Sun or a star. That single altitude measurement, paired with exact time, lets navigators compute their location on the globe. The other options describe tools for wind speed, tides, or chart plotting, none of which measure the celestial–horizon angle needed for navigation. So the described tool that measures these angles for accurate navigation is the one that fits the purpose.