On the ground you can use the Sun to navigate - the location of the Sun in the sky is something that is know as a function of time and location. A simple way to think of this is that if you are trying to figure out where east is in the morning you can get a general idea by looking at where the Sun is, although its exact location will depend on time of year and where you are on Earth.

Because the Sun's location in the sky is a function of your location on Earth and what time it is, if you know your location and orientation you can also figure out the time (that is what a sundial does).

It can be used to navigate in space too. The spacecraft I work with do study the Sun, but also have special telescopes whose main function is to detect to direction of the Sun to make sure we are pointed that way. If our pointing gets off these are used to get us oriented correctly, so we are using the Sun for navigation.

Terry

Hello! Yes, the Sun can also be used to help navigate. The Vikings used something called a "Sun Compass" or "Shadow Board" to help them determine which way geographic north was by using the shadow cast by a point on a circular board. There are legends that Vikings also used something called a "sunstone" to help them locate the position of the Sun on cloudy days. You can learn more here:

https://astroedu.iau.org/...-sun-not-your-phone/

https://www.smithsonianma...ve-worked-180968710/

https://royalsocietypubli....1098/rspa.2013.0787