This composite image shows the Sun’s path during three different events: summer solstice (top path), winter solstice (bottom path), and equinox (central path). The bright Sun corresponds to noon on the equinox. (Credit: György Soponyai/Royal Museums Greenwich/Astronomy Photographer of the Year 2021)

2024’s summer solstice is Earth’s earliest since 1796

On June 20, 2024, the summer solstice occurs at its earliest moment since 1796: when George Washington was President of the USA. Here’s why.

On average, the summer solstice occurs on June 21 of most years, as the Earth’s north pole is tilted maximally towards the Sun at a particular moment on that day. As the Earth revolves around the Sun over the course of a year, its axis remains pointed in the same direction, so that the orientation of Earth in space goes through a cycle:

• where the Earth’s north pole is maximally pointed towards the Sun (summer solstice),
• where the Earth’s north pole is aligned with the motion of Earth around the Sun (autumnal equinox),
• where the Earth’s north pole is maximally pointed away from the Sun (winter solstice),
• and where the Earth’s north pole is anti-aligned with the motion of Earth around the Sun (spring equinox).

The equinoxes and solstices given here apply to the northern hemisphere; in the southern hemisphere, seasonal equinoxes and solstices are opposed, as seasons are determined by the direction that Earth’s south pole points, rather than the north pole.