There are several synonyms that can be used instead of the phrase "apply eye to a telescope." Some common alternatives include "look through," "peer into," "gaze into," "observe through," "focus on," and "view through." These phrases can be used interchangeably to describe the act of looking through a telescope to observe celestial bodies, such as stars, planets, and galaxies. Whether you are an amateur stargazer or an experienced astronomer, using different synonyms can add variety to your writing and help to paint a more vivid picture of the act of observing the night sky.