Sunday marks the shortest day of the year in the Northern Hemisphere, signaling the start of astronomical winter. In the Southern Hemisphere, it's the longest day, marking the beginning of summer. The term "solstice" comes from Latin, meaning the sun's "pause" in its annual path. After the winter solstice, the sun begins to climb higher, and days gradually lengthen until late June. Solstices have been celebrated for ages, with monuments like Stonehenge aligning with the sun's paths. The equinox, in contrast, is when both hemispheres receive equal sunlight, leading to nearly equal day and night lengths.

Peak sunshine has arrived in the Northern Hemisphere — the summer solstice.

Spring is almost here — officially, at least.

The latest solar storm has triggered northern lights farther south than normal including into parts of Germany, the United Kingdom, New England and New York City. There were no immediate reports of disruptions to power and communications from Thursday's storm. Friday forecast shows continued higher-than-normal activity, but the chances for another overnight show are slim farther south of Canada and the northern Plains states. The sun is near the peak of its current 11-year cycle, sparking all the recent solar activity. In May, Earth got slammed by severe solar storms, the strongest in more than two decades.