The Global Sun and Shade Estimator (GSSE) can tell you - wherever you are and for any day of the year - which hours of the day there will be shade where you are standing due to objects in your surroundings (buildings, trees, hills etc). It can for instance tell you how long there is sun in the evening on the terrace of a house or at a camp site at different times of the year. It can tell the picnicker whether the sun will pass above a given tree later in the afternoon. The GSSE is supposed to be helpful for real estate agents, buyers or renters of houses, apartments and cabins, urban planners, architects, gardeners, campers, boat owners, hikers and others.

With the basic version of the GSSE you can find out which periods of the year the sun passes above any given point on the skyline (for instance a tree top). You also get to know at what hour the sun passes that point (disregarding local daylight saving time).

The advanced version can give you a complete 360 degrees diagram of sun curves, skyline and hour of the day for any place in the world and any date, see screen shots for an example.

The professional version, to be published soon, allows the user to store any number of diagrams, to upload them on the internet, and to take printouts - typically for use in selling real estate.

How it works: You let the GPS note your location (latitude and longitude), and you enter the time zone (e.g. Norway = GMT +1, Moscow = GMT +4, New York = GMT -5). You aim with your phone at points on the skyline and press the screen. The GSSE uses sensors in your phone to register the compass direction of each point and the angle at which you hold the phone compared to horizontal level. It compares these measurements of the skyline with data on the sun's height at your location at different dates and hours of the day. These data come from a mathematical model in the app. No internet connection is needed.