Today’s Favourite Object: A Planisphere


I go to a lot of museums, and thought I’d start an occasional column about unusual objects.

This is a planisphere, a star chart-computing instrument that’s in the form of two adjustable disks which rotate on a shared pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument that helps to teach how to recognize stars and constellations. The astrolabe, an instrument that has its origins in ancient Greece, is a predecessor of the modern planisphere.

The astrolabe crops up as a key plot point in Bryant & May’s ‘Seventy Seven Clocks’.

5 comments on “Today’s Favourite Object: A Planisphere”

  1. Jon Masters says:

    You can still buy these today – bought one for my son when we got him a starter telescope a year or so ago.

  2. Dan Terrell says:

    Looking forward to these columns. Thanks.

  3. snowy says:

    If people like these devices, the most famous is probably the ‘Antikythera mechanism’. The BBC did a rather fine documentary about it recently.

  4. John Howard says:

    I wonder how many the Navy bought so that their midshipmen had an aid when they needed to know where they were. On second thoughts the parents probably had to cough up the funds so that their loved ones didn’t flunk the tests.

  5. Helen Martin says:

    We just bought one but haven’t had a chance to try it out. Given the lovely clear nights we’re getting just now (we’re over the mountains from our forest fires) I should be able to learn a bit. Mind you, ours is certainly not engraved on brass.

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