Final answer:
The Maunder Minimum from 1645 to 1715 was a period of low solar activity recognized for its coinciding with the Little Ice Age in Europe.
Step-by-step explanation:
The lengthy period of solar inactivity that extended from 1645 to 1715 is known as the Maunder Minimum. This period coincided with the Little Ice Age, a time of exceptionally low temperatures in Europe that caused frozen rivers such as the River Thames and ice in oceans off southeast England, leading to a shortening of the growing season and poor harvests. The Maunder Minimum is characterized by an unusually low number of sunspots throughout the solar cycle, an observation made by astronomers like Gustav Spörer and E. W. Maunder. This phenomenon is still studied to determine the potential impact of solar activity on Earth's climate.