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Instructions for Using a Sextant

Sextants have been used for hundreds of years to help with nautical navigation. A sextant consists of a small telescope, mounted on a chassis with a few reflective mirrors and a 60-degree arc. The sextant is used to determine the angle of a celestial body (sun, moon, stars or planets) in comparison to the horizon. The angle of the arm and mirror is adjusted to align the celestial body with the horizon, and then the arc of the sextant is recorded to determine the angle of the celestial body.

Instructions

- 1
  Hold the sextant in your right hand. Focus the telescope on the horizon.
- 2
  Locate the celestial body to be used for the measurement with your naked eye. Move your arm left or right to align the sextant with the celestial body so it is on plane with the sextant.
- 3
  Move the arm of the sextant to locate the celestial body with the mirrors. The body should appear on the left side of the split view inside the telescope, with the horizon on the right side.
- 4
  Adjust the arm so that the celestial body appears just above the horizon in the telescope. Clamp the arm on the sextant to hold the celestial body in position.
- 5
  Adjust the micrometer knob to fine-tune the placement of the celestial body on the horizon inside the telescope.
- 6
  Mark the time (seconds first, then minutes and hours) and then the precise angle of the celestial body into your log.

Astronomy