Which characteristics help determine the best celestial bodies to navigate from?

The best celestial bodies for navigation are determined primarily by their brightness, the separation between them, and their altitude. Brightness is critical because more luminous stars and planets are easier to locate and identify, especially in areas with less light pollution. Separation refers to the distance between celestial bodies; greater separation can help reduce confusion in identifying which body is which, particularly when navigating in unfamiliar territories. Altitude provides context regarding how high a celestial body is in the sky, influencing visibility and the angle of observation, which can aid in precise navigation.

Other factors listed in the other choices may have relevance in specific contexts or situations, but they do not serve as primary characteristics for effective celestial navigation. For example, while shape and color can help with identification of certain celestial objects, they are not reliable indicators for navigation. Similarly, the number of observations and the time of day can inform navigational data but do not directly correlate with the selected criteria for determining the best celestial bodies for navigation.