7 May 2006

Day/Night Globe I was passing the Discovery Store in Grand Central Terminal tonight and saw two globes on display in the window. One was a political globe and the other a celestial globe. I stopped to look at the celestial globe and discovered that it is actually one globe. You plug it in and turn it on and by reflected light it is a political globe. When the light level falls a sensor turns on an internal light and the 88 ITU-recognized constellations (it says so right there on the box) shine through. I am not convinced that you would not see a ghost image of the political globe over the stars but they are probably small enough that it would take close scrutiny to detect it.

Out in the terminal I stopped to look at the stars on the ceiling and while walking to the subway remembered that they are supposed to be on the ceiling backwards as they would be if seen from outer space (Orion is not backwards but all of the other constellations do appear to be to my eye). That sent me back to the Discovery Store to see how they are depicted on the globe. As an opaque sphere a celestial globe should depict the stars as they would be seen from outer space, assuming that the stars of the constellations would maintain their spatial relationships, which we know they would not. I looked at Ursa Major, Arcturus, Spica Leo and Orion. It is strange seeing them depicted on the outside of a sphere when you are used to seeing them from inside that sphere or on a flat computer screen. But I could "arc to Arcturus and drive a spike (speed on) to Spica." Leo looked as when I last saw him resting next to Saturn. Now that I am not in front of the globe I think Orion's club may be in the wrong hand. If all of that is true the globe is the exact reverse of the GCT ceiling.

There are no prices visible on any of the window merchandise and the store was already closed so I don't know what they are getting for it.

I would be more inclined to purchase something like this if the daylight globe were a geophysical globe since they don't need to be changed as frequently as political globes. A geophysical globe would also be more in keeping with the science theme of the celestial globe.

Also in that window is their collection of Mead telescopes. All of the reracctors and catadioptrics have the objective end pointing up. The Newtonian reflectors, on the other hand, all have their mirror end pointing up, obviously you look into the back end of a telescope to see out of the front end.