An Iranian man jumps over a firework celebrating Chaharshanbe Souri, or Wednesday Feast, an ancient Festival of Fire on the eve of the last Wednesday of the Persian year, in Tehran, Iran, Tuesday.

Spring officially begins today (March 20) with the vernal equinox, bringing longer days and warmer temperatures to the Northern Hemisphere. The vernal equinox signals the astronomical start of spring ...

Day and night will get equal time for a brief moment Monday as much of the world heads into fall. The autumnal equinox arrives Monday, marking the start of the fall season for the Northern Hemisphere ...

The autumn equinox is now upon us! Today marks the moment that the sun crosses the celestial equator, ushering in the beginning of astronomical autumn in the northern hemisphere, which brings with it ...

Scientists say Earth’s northern half is darkening faster than the south, reflecting less sunlight back into space and soaking up more of the sun’s energy. A new study based on more than two decades of ...

Spring is here — officially, at least. The vernal equinox arrives on Thursday, marking the start of the spring season for the Northern Hemisphere and the fall in the Southern Hemisphere. On the ...

New research from an international group looking at ancient sediment cores in the North Atlantic has for the first time shown a strong correlation between sediment changes and a marked period of ...

Peak sunshine has arrived in the Northern Hemisphere — the summer solstice. Friday is the longest day of the year north of the equator, where the solstice marks the start of astronomical summer. It’s ...