How the sun aligns on the summer solstice, the longest day of the year
How do they know that? So summer solstice is really important here at Stonehenge. It's one of the key things that we actually do know for sure that the monument was built on the summer and winter solstice alignment. So once every year, the sun aligns with the main entrance into the monument, and people come here to gather to celebrate this this wonderful occurrence. So the solstice is the longest day of the year. And what that means is we see the sun in the sky for the longest period of time. Our Earth is spinning on its axis once every 24 hours, but depending on our tilt, we're going to be seeing it in the sky for longer or shorter periods of time. It's just going to be in the right direction for a longer amount of time for today. So during the solstice, about 16 hours of of sunlight can be expected, and I'm much, much shorter at night. In terms of measuring when the solstice is, we can observe the sunrise and sunset times and when they are the furthest apart. That's how we know the solstice is happening. It's a great time for solar observation because the sun is in the sky for the longest amount of time, but a little bit annoying for everything else as a lot of astronomy is done at night so the shortest night of the year is not particularly ideal.