On Apr 24, 2:23*am, George > wrote:
> On 4/24/2011 12:00 AM, dsi1 wrote:
>
>
>
>
>
> > On 4/23/2011 3:51 PM, Nancy Young wrote:
> >> dsi1 wrote:
> >>> On 4/23/2011 9:57 AM, Nancy Young wrote:
>
> >>>> Yeah, all those apps doing whatever they want without you knowing,
> >>>> who signed up for that. Installing data collecting or whatever it is
> >>>> they do.
>
> >>> I have to turn on the location services when I use apps like Google
> >>> Sky. It's a hassle but it's a super bitchin' app. Thanks Google!
>
> >> Some of the stuff looks like a lot of fun, that's for sure. And a lot
> >> of the apps look really handy, too.
> >> nancy
>
> > Google Sky will give you a star map on your display that's somehow
> > coordinated to the night sky. It labels your view. Beats the heck out of
> > me how it can do this.
>
> The visible night sky is well mapped and there have been apps around for
> a long time. If you know your position on earth and the time of day you
> can present the appropriate map showing what it is possible to see.
> Pretty much the same as the way a GPS displays a map. It determines
> where it is relative to a model of the earth and then gets the known
> mapping info it has for that location and displays it.

Computer star maps have been around for a while. This is different.
Google Sky can transpose the star map against the sky. It has to know
the azimuth and degree of tilt of the phone in addition to the GPS
info. It calculates this in real time. Somehow it knows the
orientation of the phone in space. As far as I know, I've never
calibrated the phone.