Which device is used to calculate longitude due to precise timekeeping?

Which device is used to calculate longitude due to precise timekeeping?

• A. Cryptochromes
• B. The log and line
• C. Chronometer
• D. Olfactory navigation

Answer: (C)

Longitudinal position is determined by comparing the local solar time to a fixed reference time kept at a known longitude. A marine chronometer provides a highly accurate, stable time standard at sea, even with motion and changing conditions. By knowing Greenwich Mean Time with the chronometer and observing when the Sun is at its highest point locally (local noon), sailors measure the difference between local time and GMT. Each hour of time difference corresponds to 15 degrees of longitude, so the longitude can be calculated from that time difference. This is why a chronometer is the tool used for calculating longitude through precise timekeeping. Other options don’t fit this purpose: cryptochromes are light-sensitive proteins involved in biological processes, not navigation; a log and line measures distance traveled for dead reckoning, not precise time-based longitude; olfactory navigation relies on smell, not timekeeping.

Longitudinal position is determined by comparing the local solar time to a fixed reference time kept at a known longitude. A marine chronometer provides a highly accurate, stable time standard at sea, even with motion and changing conditions. By knowing Greenwich Mean Time with the chronometer and observing when the Sun is at its highest point locally (local noon), sailors measure the difference between local time and GMT. Each hour of time difference corresponds to 15 degrees of longitude, so the longitude can be calculated from that time difference. This is why a chronometer is the tool used for calculating longitude through precise timekeeping.

Other options don’t fit this purpose: cryptochromes are light-sensitive proteins involved in biological processes, not navigation; a log and line measures distance traveled for dead reckoning, not precise time-based longitude; olfactory navigation relies on smell, not timekeeping.