Our friend Kevin Kelly wrote on EarthSky on G+:
The largest human migration these days takes place every year around this time: Chinese Lunar New Year. Hundreds of millions of humans take every possible avenue to return to their home villages from the cities they now live in. In a space of about one week to 10 days, 3.6 billion passenger miles will be clocked on trains, buses, and cars. The Chinese search engine company Baidu (Google equivalent) created a heat map of these trips gathered from the locations provided by the smartphones of their 200 million subscribers. The three densest nexus you see here are Beijing, Shanghai and Hong Kong/Shenzhen.
Thank you, Kevin!
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.