Planisphere

A planisphere is a physical or digital star chart designed to show the visible stars and constellations for a specific time and date at a given latitude. It typically consists of two adjustable circular discs. The lower disc, which represents the sky, contains a map of the stars and constellations. The upper disc has a window, usually shaped like a distorted ellipse representing the horizon, that rotates to align with a given date and time. This allows the user to easily identify the celestial objects visible at that moment from their location. Modern versions can be digital, using apps on phones or tablets to simulate the function, with the ability to incorporate augmented reality. The accuracy depends on proper calibration and the user's location and observing time.

Planisphere meaning with examples

• Using the planisphere, Sarah easily located the constellation Orion in the night sky, noting its characteristic belt of three stars. The rotating disc precisely matched the time and date, revealing the exact positions. She used its latitude scale. It greatly simplified her stargazing experience.
• Before their camping trip, the family consulted their planisphere to prepare for a night of astronomical observation. They learned the specific stars and planets visible from their campsite. The planisphere, in conjunction with the included compass helped them find their way and was a crucial tool for their viewing plans.
• Despite the city's light pollution, the astronomy club members found that their planispheres helped them to identify the brightest stars and major constellations. They calibrated their planispheres for the exact time, helping them see the faint shapes and understand the complexities of space.
• An experienced astronomer uses a planisphere to quickly get their bearings and identify deep-sky objects that they cannot otherwise find, planning their night of observing. They used the coordinate system to find the precise location of the objects.
• A digital planisphere on a tablet offered real-time information about the visible stars. This allowed the user to easily identify constellations in the sky. The app's interactive features brought a new dimension to astronomy, helping them learn and understand the stars.