A planisphere is a useful tool for amateur astronomers and stargazers to identify and locate celestial objects in the night sky. It is a circular map or chart that represents the entire celestial sphere as viewed from a specific location on Earth. The chart typically consists of two rotating disks: an outer one with a transparent window and an inner one with a map of the stars.

Here's how a planisphere works:

  1. Location and Time Setting: To use a planisphere, you need to set it to the correct date and time. Most planispheres have a rotating disk for the date and time that allows users to align it with the current date and time.
  2. Aligning with North: Before using the planisphere, you should align it with the north direction. This is usually done by pointing the transparent window (representing the portion of the sky visible) towards the north.
  3. Identifying Celestial Objects: The map on the planisphere shows the arrangement of stars and constellations in the night sky. When you align the date and time on the planisphere with the current date and time, you can use it to identify which stars and constellations are visible at that specific moment.
  4. Motion of the Stars: As the Earth rotates, the stars appear to move across the sky. A planisphere takes this into account, allowing users to see how the night sky changes over time.

Planispheres are excellent tools for beginners as they provide a simple and interactive way to learn about the night sky. They are particularly helpful for locating prominent constellations, stars, and other celestial objects without requiring a deep understanding of celestial coordinates.

You can find planispheres designed for different latitudes and regions, as the appearance of the night sky varies depending on your location on Earth. Additionally, some planispheres include additional information, such as the positions of planets, deep-sky objects, and major stars.

Download a planisphere as pfd, for printing

Star Map