"Reach out and touch someone"

The map shows the results from using an automated, digital radio propagation tool (WSPR - Weak Signal Propagation Reporter). The dots and connecting lines show where other ham radio operators heard my WSPR transmissions.

The lines are color-coded by the frequency band used. The bands have differing propagation characteristics, which vary by time of day, and many other factors, such as sunspot activity, geomagnetic activity, etc. Those all affect how the ionosphere either absorbs, or refracts the transmitted signals, and in the latter case, sending them back down to earth hundreds or thousands of miles away.

Neat shite, yo.