Caoimhín's Content

Today we are yet again going to take a look at the solstice, but we are going to look at the solstice in another, slightly different, way. In a recent piece, we took a look at the solstice from the Moon. We’re starting a few days before the solstice, the 16th, so the Moon is very close to the New Moon.

There’s a nice conjunction coming up between Venus and the Moon on the 17th. As we approach the solstice, the Moon comes closer to full. On the solstice, on the 21st, we know that it’s pretty much a Half Moon, the First Quarter Moon. When we look at the Earth from a First Quarter Moon, the Earth also looks like a Half, so we get to see the daytime side, the terminator, and the nighttime side. We’re going to go the other way, back to the 15th. Then, the Moon was pretty much in front of the Sun, more or less a New Moon. If we were on the New Moon looking back at the Earth, what we would see is the daytime side, we would see the fully illuminated face of the Earth, and that is what I want to take a look at. We’re not on the solstice because the New Moon isn’t on the solstice this year, so unfortunately, we can’t get this view on the solstice. We could look at the Earth from the Sun, but I want to take the closer view of the Moon.

From the Moon, the Earth is visible rotating, we will stop on Europe. Just like the last time, the island of Greenland is visible with a little bit of a line where it joins the Arctic ice sheet itself. As the Earth rotates, the Arctic stays in daylight. Even when Greenland is on the far side of the Earth relative to the Sun, it is still illuminated. It is only roughly opposite the Sun, as we are looking from the Moon. The Moon isn’t perfectly new, so we’re looking at the Earth illuminated 98.1% rather than 100%. There is a little bit of a shadow along one side, but that isn’t going to interfere too much. With sunlight falling on that part of the world, the Sun isn’t setting. That part of the world doesn’t actually turn away from the Sun because the Earth’s axis of rotation is tilted towards the Sun at this time of the year. There is a reasonable portion of the Earth that sees daylight all the way through the night, around the night of the solstice. Of course, for the North Pole, for the very top of the planet, the midnight Sun lasts for months, and there is a reasonably long transitionary period. For areas that are lower in the Arctic Circle, the midnight Sun doesn’t last for as long, and further down, under or outside the Arctic Circle, closer to the equator, there are areas such as Ireland and large portions of England where twilight exists all night long, but the Sun isn’t actually above the horizon, through the middle of the night on the solstice.

We’re going to go to northern Norway as an example. We’re going to Bodø, because that is a city very far north in Norway. That puts us at roughly at 67 degrees north latitude. That’s quite far north, just barely inside the Arctic Circle. We’re going to take a look from close to the solstice, a few days before the solstice, and we’re going to see what it looks like. We’re going to stay focused on the Sun, but it’s important to notice the cardinal directions as well. The Sun is still reaching its highest in the south and then it dips down towards the west. The Sun is still moving across the sky in the same way, going the same direction. Well, the Sun isn’t moving. The Sun is staying in one place and the Earth is turning, but the Sun’s apparent position in the sky is changing. The Sun doesn’t just stay in one place, the Earth is still turning.

The Sun continues to dip down as it passes the northwest heading north. The Sun stays above the horizon, when you’re far enough north, even when the Sun is to the north. You’re essentially seeing the Sun over the North Pole in that direction, because the Sun is still above the horizon just a little bit further north. However, it looks like the Sun isn’t above the horizon, it looks like the Sun has actually set. Regardless, the sky is still bright, it’s still basically daytime. Technically, if the Sun is below the horizon, it is very early twilight, civil twilight, but there are no stars visible, nothing is bright enough to shine through this glow. The Moon would be, of course, but then again, the Moon is visible during the day. The Sun appears to be set, but if we remove any blockages on the horizon we’ll get a clearer view. With a perfectly flat horizon, the Sun is still above it. It’s tough to tell with the trees and buildings in the way, but this means it is absolutely still daytime, the Sun is above the horizon even when it reaches its lowest in the north.

Just as the Sun reaches its lowest, very briefly, the narrow Crescent Moon is visible. It would not be bright enough to be visible under most daytime conditions, but with the Sun so close to sunset, it just about peeks through. What I really wanted to illustrate is that the Sun does still move across the sky. The Sun doesn’t rise in the east and set in the west, because it doesn’t set at all, but it still moves. It is very similar to how the sunrise and sunset works here in Ireland and at more medium latitudes. The Sun will rise further and further north and set further and further north as we approach the solstice. From Bodø we are far enough north, close enough to the solstice, that the Sun doesn’t actually set at all. It skirts along the northern horizon from above and doesn’t go underneath. What I really wanted to illustrate here is that the apparent position of the Sun in the sky does change, the Earth is still rotating and the Sun does get lower, as if it was about to set, but it doesn’t quite make it.

Now, this view is fairly far north in Norway, so I will pull us down a little bit lower, down to about 61 degrees north instead of 67. This is definitely lower, and I will bring us back to a little before the solstice again. From this lower latitude, the Sun does dip below the horizon. That is sunset, even if it occurs almost due north and leaves the sky quite bright. The Sun dips below the horizon on the 16th, and it is far enough below the horizon that Venus becomes visible as well as the Moon. Looking at around local midnight, and in the sky there are stars visible, just barely. Vega and Arcturus at least, two of the brightest stars, are just about visible. Hopping forward a couple of days and even on the 21st, even on the solstice, it is still below the horizon. So of course this means we’re too far south to get the midnight Sun. We will go in between, to 64 degrees. This is not quite far enough, the Sun isn’t quite above the horizon even there on the solstice at midnight. That’s really what we’re looking for, to see where the Sun remains up at around the local midnight, close to 12 o’clock. We’ll go to 66 degrees north, close to 67 degrees, and the Sun is above the horizon, in the right place at the right time. We’ll come back down to 65 degrees and about 50 minutes, and the Sun is on the horizon. It doesn’t fully sink below the horizon entirely. The Sun is just barely skirting the northern horizon, the disk of the Sun left as a semicircle. This is very much the in between condition. The Sun almost sets, but doesn’t fully set on the night of the solstice.

Let’s continue tracking the Sun around the sky, but we’ll come back to the beginning of the 21st. The Sun rises up from its low point to the north and it reaches its highest in the south. It gets pretty high in the sky and it’s definitely a bright summer’s day. Then the Sun starts coming down towards the west, eventually just about touching the horizon to the north, but not entirely sinking under it. Of course, this is with the distortion of the atmosphere. If the Earth lost all of its atmosphere, the Sun would absolutely be below the horizon, but we do have the atmosphere and that’s usually what we count. We don’t worry about when the Sun is actually above or below the horizon, we count the refraction of the atmosphere and factor that in. We’re it’s 65 degrees, 52 minutes and about 33 seconds of arc. That brings us to a location where the Sun skirts the horizon on the solstice, doesn’t fully set, doesn’t fully rise, but regardless of where you are, the Earth is turning, and so the apparent position of the Sun and the sky will move with it. The true Arctic circle is just about 66 degrees and 30 or so minutes, but this does change over time.

I hope that you enjoyed this piece. If you would like to see the solstice or around the solstice from some different views, like from the Sun and from the Half Moon, the First Quarter Moon, you can take a look at one of the recent pieces on this website. If you enjoyed this piece, please do like it and make sure to subscribe to this website and my YouTube channel. Most importantly, thank you very much for reading and hopefully I’ll see you back here next time.