Hipparchus is credited with the invention or improvement of several astronomical instruments, which were used for a long time for naked-eye observations.

Casual observers tend to see what they expect to see, and naked-eye observations of the full Moon are a case in point.

Despite this, some knowledge appears to have been produced from introspection and naked-eye observation.

Ganymede and Callisto, at their maximum separation, are the likeliest targets for potential naked-eye observation.

Why should observations through a telescope be preferred to naked-eye observations?

The hard core was protected by changing the theory underlying the observation language, so that telescopic data replaced naked-eye observations, for instance.

His naked-eye observations and dogged investigations have built powerful cases against suspects in several hit-and-run cases.

He published drawings of naked-eye observations of the Milky Way in 1892, made over a period of six years.

Around 1603, William Gilbert compiled the first lunar drawing based on naked-eye observations.

It predicts the positions of the planets accurately enough for naked-eye observations, so it seemed accurate at the time.