Unravel the Night Sky from Any Location

Planisphere star chart

Our **Planisphere** is an innovative and intuitive tool designed to make stargazing and celestial navigation accessible to high school students and astronomy enthusiasts alike. Unlike traditional planispheres, its unique design integrates Earth's geography, allowing for a truly personalized view of the cosmos.

How It Works:

  1. **Rotating Star Chart Overlay:** The instrument features a primary circular overlay, a **star chart**, which shows the constellations and celestial coordinates.
  2. **Stereographic Earth Map Base:** Uniquely, positioned beneath this star chart is a **circular stereographic Earth map**. This map shows landmasses and geographical longitudes.
  3. **Dynamic Alignment:** Both the star chart and the Earth map are connected at their centers, allowing them to **rotate freely** around a common axis. To see the sky from any location on Earth, simply rotate the star chart and the Earth map until a specific **Right Ascension** on the star chart aligns with your desired **Earth longitude** on the stereographic map.

How to use it:

  1. **Find your current location:** Identify your geographic longitude on the central Earth map. Determine Greenwich Mean Sidereal Time (GMST): Using an online calculator, or the built-in sidereal clock on the planisphere (if available), find the current GMST.
  2. **Align the celestial sphere:** Rotate the constellation wheel until its Right Ascension (RA) hour scale aligns with the GMST reading on the longitude scale of the Earth map.
  3. **Find your sky:** Hold the planisphere so that the arrow points to the north, and the position of the sky directly above you is at the Zenith point (center) of the constellation wheel. The constellations on the chart will now accurately reflect the view from your location and time.

For example:

  1. If the current date and time is May 4, 2025, 02:16:29 UTC, the Greenwich Mean Sidereal Time (GMST) is approximately 22h 16m 29s.
  2. To use your planisphere, you would: Find your longitude on the Earth map (e.g., 0° for London, UK). Rotate the constellation wheel until the 22h 16m mark on its Right Ascension scale aligns with the 0° Prime Meridian on the Earth map.
  3. The planisphere is now set for the entire globe. You can now determine the visible constellations from your location by looking at the part of the map that corresponds to your longitude.

Key Features & Benefits:

Global View of the Sky

Easily determine which stars and constellations are visible from any geographical location on Earth at any given time.

Enhanced Learning

Provides a tangible way to understand the complex interplay between Earth's rotation, your terrestrial position, and the apparent movement of the celestial sphere.

Intuitive & Interactive

Its hands-on, rotating design makes learning astronomy more engaging and less abstract.

Durable & Portable

Built for long-lasting use, perfect for classroom demonstrations or outdoor stargazing sessions.

"Your window to the universe, from anywhere on Earth!"

Get Your Planisphere Today!