Sun's up on the longest day of the year...

PEAK sunshine has arrived in the Northern Hemisphere - the summer solstice.

- BY DANNY DE VAAL

Yesterday was the longest day of the year north of the equator, where the solstice marks the start of astronomical summer. It's the opposite in the Southern Hemisphere, where it is the shortest day of the year and winter will start.

The word “solstice” comes from the Latin words “sol” for sun and “stitium” which can mean “pause” or “stop.”

The solstice is the end of the sun's annual march higher in the sky, when it makes its longest, highest arc.

The bad news for sun lovers: It then starts retreating and days will get a little shorter every day until late December.

People have marked solstices for eons with celebrations and monuments, including Stonehenge, which was designed to align with the sun's paths at the solstices.

But what is happening in the heavens? Here's what to know about the Earth's orbit.

As the Earth travels around the sun, it does so at an angle relative to the sun. For most of the year, the Earth's axis is tilted either toward or away from the sun.

That means the sun's warmth and light fall unequally on the northern and southern halves of the planet.