Charts, Planispheres & Software

- Demonstrate the use of a planisphere, star chart or computer software in order to plan an observing session
- Demonstrate an understanding of the terms 'ecliptic' and 'zodiacal band' on a star chart

A planisphere is a quick and easy way to find out what stars are viewable at any time.

It consists of two discs fastened to each other. On one of them is a hole so that a portion of the disc underneath can be seen. Around the edge are hours of the day. On the underneath disc is a star map showing every constellation available for viewing from a general location e.g. Northern Europe. Around the edges are equally spaced days of the year.

The edge of the round area represents the horzon. The ecliptic is a line through which the Sun and planets appear to move, and cuts through constellations known as the Zodiac.

To find the stars available on 4th September at 10pm you would move the hour dial that says 10pm on the overlay next to the date on the underlay and point the planisphere north to see a representation of the stars available in the sky at that time.

The two discs are fixed at the pole axis (so Polaris is not shown).

Star maps and charts are published in books, newspapers and magazines. They tend to show what is in the sky during a month or season. Frequently there are two maps, one showing the view of east to west towards the south, the other showing the view of west to east towards the north.

Software can show the sky at any given moment and can offer other features like maps of planets etc. Stellarium is free and is updated with new features and objects.