DENVER (KDVR) — There are many ways to mark the start of summer.

Meteorologists count the entire months of June, July and August as “meteorological summer.” Most people, however, use the summer solstice as the official start to summer, which this year falls on June 20 at 2:50 p.m. MDT.

The summer solstice happens the same way that most of the planet’s seasons are prompted: because of Earth’s rotation around the sun, and Earth’s tilt on its axis.

The summer solstice is when Earth’s northern hemisphere is at its maximum tilt to the sun.

The word solstice comes from the Latin words “sol,” which means sun, and “sistere,” which means to stand still. This is fitting because the summer solstice represents when the sun is at the highest point in the sky.

This leads to what most people call “the longest day of the year,” because it’s the day when the northern hemisphere sees the longest amount of daylight. In Denver, the solstice will bring 15 hours of daylight.

As Earth continues its rotation around the sun, the northern hemisphere will gradually lose the amount of daylight it sees per day until the winter solstice.

The winter solstice this year falls on Saturday, Dec. 21, 2024, at 2:19 a.m. That day, Denver will only have 9 hours and 21 minutes of daylight.