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But if I’m gonna carry a sunstone, why not just carry a small compass. Also, a sunstone won’t help you if the sun is obscured by terrain or trees.

Maursault 4y ago
It's a different application, and there are no trees or terrain on the ocean. The sunstone reveals the position of the Sun when the sky is overcast, and from the position of the Sun one can not only determine direction, but also time of day. If there is a way to use a compass to tell the time of day and the position of the Sun when the sky is overcast, I'd love to learn it.
- riversflow 4y ago
  Well the OP is about using a watch to find North. As I understand, a sextant can be used with a nautical chart, a compass and an accurate time keeper to find position, as long as a horizon can be found and you have an idea of your latitude. While a cool viking discovery, they aren’t really practically useful.
  - Maursault 4y ago
    > Well the OP is about using a watch to find North. False, or at the very least this description is incomplete. OP concerns using a watch and, critically, the position of the Sun to determine cardinal directions. If the Sun can't be located, the exercise is pointless. > As I understand, a sextant can be used with a nautical chart, a compass and an accurate time keeper to find position, A sextant is used to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation. If the sky is overcast, a sextant is useless. Earth's skies are cloudy, and at any time 67% of the Earth's surface is typically covered by clouds, and this is especially true over the oceans where less than 10% is entirely clear of clouds.[1] But in the case of having a sextant, nautical chart and a time keeper, under overcast skys, the sunstone can replace the compass and permit the function of the sextant, and one would still be able to find position under overcast skies that would be impossible without the sunstone and with a compass. > as long as a horizon can be found This is not a given as weather rarely cooperates. Fog is a common occurrence on the ocean, and it will conceal the horizon. > and you have an idea of your latitude. I'm pretty sure those 4 items are all that is necessary to determine latitude. > While a cool viking discovery, they aren’t really practically useful. As explained above, on the ocean, cloud cover ordinarily obstructs the position of the Sun. So a sunstone is practical under common conditions on the ocean of skies obscured by cloud cover. [1] https://earthobservatory.nasa.gov/images/85843/cloudy-earth https://earthobservatory.nasa.gov/images/85843/cloudy-earth

Maursault 4y ago

It's a different application, and there are no trees or terrain on the ocean. The sunstone reveals the position of the Sun when the sky is overcast, and from the position of the Sun one can not only determine direction, but also time of day. If there is a way to use a compass to tell the time of day and the position of the Sun when the sky is overcast, I'd love to learn it.

riversflow 4y ago
Well the OP is about using a watch to find North. As I understand, a sextant can be used with a nautical chart, a compass and an accurate time keeper to find position, as long as a horizon can be found and you have an idea of your latitude. While a cool viking discovery, they aren’t really practically useful.
- Maursault 4y ago
  > Well the OP is about using a watch to find North. False, or at the very least this description is incomplete. OP concerns using a watch and, critically, the position of the Sun to determine cardinal directions. If the Sun can't be located, the exercise is pointless. > As I understand, a sextant can be used with a nautical chart, a compass and an accurate time keeper to find position, A sextant is used to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation. If the sky is overcast, a sextant is useless. Earth's skies are cloudy, and at any time 67% of the Earth's surface is typically covered by clouds, and this is especially true over the oceans where less than 10% is entirely clear of clouds.[1] But in the case of having a sextant, nautical chart and a time keeper, under overcast skys, the sunstone can replace the compass and permit the function of the sextant, and one would still be able to find position under overcast skies that would be impossible without the sunstone and with a compass. > as long as a horizon can be found This is not a given as weather rarely cooperates. Fog is a common occurrence on the ocean, and it will conceal the horizon. > and you have an idea of your latitude. I'm pretty sure those 4 items are all that is necessary to determine latitude. > While a cool viking discovery, they aren’t really practically useful. As explained above, on the ocean, cloud cover ordinarily obstructs the position of the Sun. So a sunstone is practical under common conditions on the ocean of skies obscured by cloud cover. [1] https://earthobservatory.nasa.gov/images/85843/cloudy-earth https://earthobservatory.nasa.gov/images/85843/cloudy-earth