Posted by & filed under GIS, Technology.


Some places on earth have different gravities.  Gravity roughly decreases with altitude, and many things can affect it.  The linked article explains that the European Space Agency are trying to get a better image of the earth’s gravitational pull.  There is also some talk about how this study can help us understand climate models better.

Probe launches to map Earth’s gravity in best detail yet. (via New Scientist)

They have a disclaimer right on the webpage about copying content, so I used an image from NASA.  Click through to see their video on the subject.

Some more links for you:

Posted by & filed under America, GIS, Mobile, Technology.

It may seem obvious that the maps stored on GPS devices is not always correct.  Not only is the data collection itself prone to error, but they are a static snapshot.  Maps change overtime, new roads are built, natural disasters take out roads, and civil projects can lead many roads and towns to be at the bottom of a lake.

There was an episode of the office where one of the characters drives his car into a lake, because his GPS told him so, a clip can be found here.

The linked article doesn’t take into account error with the GPS itself.  GPS error is very common, especially in areas where the signal can reflect or be distorted.  A popular example of this can happen in an Urban Canyon.  I have seen a GPS estimate its location as being on a major highway, when a vehicle was traveling on a frontage road, as well as some very peculiar effects biking through New York City.

While not as readable as a USA Today article, Wikipedia has a very good article up on errors in GPS reception.

Caution: GPS devices aren’t always right. (via USA Today)

Posted by & filed under America, GIS.

(T = 9:30 EDT, March 11, 2009)

(T = 9:20 EDT, March 11, 2009)

If it’s not too cloudy tonight, we should be able to see the Shuttle Launch!

Weather permitting, people within about a 500-mile (800-kilometer) radius of the central Florida coast will be able to see the flare from the shuttle’s solid-fuel rocket launchers two seconds after launch for about two minutes.

From two to eight minutes after launch, Discovery’s main engines will make the shuttle seem to burn like a flickering, yellow-orange star.

People with binoculars may even be able to make out the shuttle’s V-shaped tail.

Shuttle Launch to Be Visible to Most of U.S. East Coast. (via National Geographic)

Posted by & filed under America, GIS.

Screenshot from is providing maps of Fatal Accidents and DUIs.  A lot of useful information!

I’ve been looking up clusters in my area.  It seems that Union Blvd in East Allentown is pretty dangerous.  It is a four lane road roadway with a lot of businesses and intersections.. really it seems like a pretty deadly scenario. Maps Fatal Accident Hot Spots. (via