Daylight map

[FORTUNATO]

Realy cool......

Introduction
DaylightMap shows the pattern of night and day on a Google map, for any area of the Earth, for any date and time. It also allows you to select up to ten locations on the map; in addition to seeing at a glance whether it's daytime there, you can show their local time, sunrise and and sunset times, and length of day. These locations can be remembered for future visits, saved as a bookmark, or sent to other people as a web link. This site can thus function as a graphical world clock, and can be used to show relative times of any future or past event.

It can even show just the night-time city lights, correlated to the base Google satellite view (on better browsers). Which has nothing to do with daylight per se, but is pretty cool to look at nonetheless.

There's also a near-real-time view of global cloud cover available, updated every hour from weather satellite imagery. It's interesting both for looking at the big-picture patterns, as well as a more localized picture of what the weather is doing in your part of the world. A specialized cloud-cover view is available as well, my Hurricane Watcher.

And more toys are coming soon!


Acknowledgements
My best reference in developing the sunrise, sunset, and Earth-shadow aspects of this site was the list of formulae at Paul Schlyter's pages. I found the Basics of Positional Astronomy helpful as well.

I also owe an algorithmic debt of gratitude to the open source at EarthView, which generates some similar daylight-shadow views to this one. You'll notice their curves are a different shape than mine — that's because they use a different map projection than Google's Mercator. This holds true for many of the other terminator plots you'll find floating around the infosphere as well.

Oh, and that reminds me, MathWorld has a very informative page on the Mercator projection and its associated equations.

The city light imagery shown on the night side of the Satellite and Hybrid views is from NASA's Visible Earth catalog. Although I'm using the highest resolution they offer, it's still only acceptable through about the first half of the Google Map's zoom range, so beyond that I suppress the city lights.

Which brings up another point: Although this site shows a real-time day/night terminator, the satellite imagery underlying it is not real-time. The city light photos date from 23 October 2000, and Google Maps' satellite photos are of varying ages (for more information, see Google Maps Help on the topic).

Other credits: The local times shown here use the Web Services from EarthTools.org, augmented with a patch of my own making for Daylight Saving Time. And the address lookup feature uses the Yahoo! Geocoding API. My thanks to both of these services.


DaylightMap

About DaylightMap.com

[Bent_Bladi]

nice! thanks fortunato ... this can be useful