On 4/24/2011 5:13 PM, dsi1 wrote:
> On Apr 24, 2:23 am, > 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.

It uses a solid state gyro to know its orientation/acceleration.