This paper considers a longitude distribution of sunspot groups over 1982–2013, using data from the National Geophysical Data Center (Boulder, USA). The space-time distribution of sunspot groups is analyzed in coordinate sectors calculated from heliographic longitudes of the groups. A longitude extent of a coordinate sector is compared to the average size of one active region (30–40°). Then, in...

In the 1700s, scientists, sailors, engineers and explorers were trying to work out how to navigate east to west at sea. The stakes were high; many lives were lost because sailors could not reliably measure longitude. Eventually, the invention of accurate timepieces allowed sailors to use the time in their current location, and the time at a fixed reference, to calculate longitude. But how do lo...