Planisphere

[ThunderStorm]

I am wondering is Planisphere can be used all year round?

[Merlin66]

Sure can.
Just set the dial to the required date.

[SteveInNZ]

Not only that, the battery doesn't go flat, you don't need an internet connection and you can fan yourself if it's hot.

Steve.

[sil]

Besides being a great fly swatter and a beer coaster I have a followup question. Do planispheres "drift out of alignment"? in that is its calendar only accurate for one year and each year is out by a day or so? So do they have a usable lifespan or are they perpetually usable? Maybe similar to how a calendar is only accurate for one year yet about 12yrs or so on it will be perfectly accurate again.

I appreciate that probably for a lifetime its drift wont make the planisphere unusable but will its calendar drift away and back again periodically so for practical use its perpetual?

[SteveInNZ]

It's reasonable to say that it's good for your lifetime. Mine has a table of planet positions that only goes as far as 2020 but the star positions are the same year after year.
You can't beat them for explaining how the Milky Way moves across the sky.

Steve

[sil]

thanks, so its probably the best investment you can make in astronomy. It's rare to be able to buy anything that actually can work for an actual human lifetime

[ThunderStorm]

Thanks.
Any place can find the planisphere available?

[raymo]

I think any Dymocks or Angus and Robertson will either have one, or
will get one in for you. I'm pretty sure that Sky and Telescope magazine
also sell them via ads in the magazine.
raymo

[Red_Dog]

IceInSpace shop right here sells them for $15.
National Geographic shops sell a large plastic one for about $27.

Download an app for your smart phone.
Sky portal - free
Star chart - free
They show you what's in the sky now. Great tools for the amateur astronomer.
Happy sky hunting.