Caoimhín's Content

Today, we are going to pick up with something I mentioned at the end of the previous piece. I mentioned how your height off of the ground, your elevation, can change when you’ll see things and how you’ll see things. Stellarium does allow you to change your elevation, but not quite in the way that I had hoped. To begin, we’re going to look at sunset for around the middle of February from the usual location, which is about 10 meters off the ground. This isn’t far off the elevation for at least some parts of Cork City, but usually the latitude and longitude are much more relevant.

Of course, the “ground” of my videos, the Stellarium landscape which I use, that area isn’t Cork City but a piece of countryside in Guéreins, in France. According to the notes in Stellarium, that area, the whole field with buildings and hedges, is closer to 83 meters above sea level. This still isn’t particularly high, but it is certainly higher than the 10 meters that we’re showing here. If you were able to rapidly climb from 10 meters to 83 meters above the ground, in a balloon or by going up a tall building, you would be able to see a little bit further, it would be as if your horizon got lower.

Unfortunately, when we change our elevation here in Stellarium, it doesn’t simulate you, the individual or viewer, climbing up from 10 meters to 100 meters above the ground. Rather, it shows what your view from an area would be like if that area was at 100 meters above the sea level, or whatever the increment. The horizon is essentially coming with you. It doesn’t simulate the kind of change in view you’d get from going up a tall building, it more simulates the change in view you’d get going up onto a plateau if you were on a very tall mountainous region. Of course, if you were at the peak of a mountain looking down on a plain all around you, or off of a cliff or into a valley, then you would get to see a little bit more, similar to how going up a building lets you see a little bit more. We’re not going up to a peak at 1000 meters with a slope all around, we’re still on a field, which is now being simulated as a thousand meters above the sea level.

This does cause changes. The sky is a little bit brighter at a given time from 1000 meters than it is down at 10 meters. Even though we are simulating our view from a plateau rather than from a high point, we are still getting higher and higher in the atmosphere, so we’ll see the glow of sunset for a little bit longer, the day will essentially be a little bit longer. However, we’re not going to be able to see things much longer in the sky. We’re not going to see Saturn for longer from when it appears to when it sets, because we won’t be able to see over the horizon by climbing higher, Saturn will still go under the bushes and trees, as the horizon sort of comes with us, even up to 10,000 meters above the ground in the Stellarium simulation. This certainly causes the sky to change as the atmosphere gets thinner.

We can climb even further, up to 100,000 meters above sea level, which certainly makes the grassy field representing the ground seem a bit preposterous, but the horizon continues to raise as if we were standing on a vast plateau. despite looking at a sunset sky, this last climb puts the sky into complete darkness. We are very nearly above the atmosphere at this point. The atmosphere is at least so thin from this incredible simulated height that we’re able to see the planets and the Sun at the same time. From this vantage point, we can even see Mercury right next to the Sun in the sky. This would sort of be your view from a weather balloon or a similar object floating at the edge of space. We’re only at the edge of space here, there is still a little bit of blue to the sky. Stellarium has simulated all the atmospheric effects quite well, such as how the sunset length will change, but it doesn’t simulate the extra amount we’d normally see or the amount we’d expect to see if we were traveling up to a peak or up a tall building.

Coming back to sunset and looking at Saturn just above the horizon and dropping down from the incredible height, the brightness of the sky will change, but the position of Saturn relative to the horizon doesn’t change. IN this simulation, we’re sort of bringing the horizon with us on this up and down journey. Even simulating the mathematically perfect zero horizon as we did last time, there are no changes in apparent height. Looking ahead to the parade of planets as an example, around the 24th of February this lets us simulate how we would be able to see it from Ireland if conditions were perfect. Of course, getting this really flat horizon is going to be very, very difficult.

If we were traveling up a mountain, we’d expect to see Mercury and Saturn almost get higher in the sky, because we’re moving up and looking further over the horizon. If we were going up a tall building or a mountain, the horizon would seem to lower. In Stellarium, you can sort of imagine the vast green circle representing the ground that we’re on as a huge elevator. A huge elevator platform so wide that you can see all the way to its horizon, and it has its own horizon because it’s such a huge elevator platform. As this elevator platform goes up from 10 meters to 100 meters, from 100 meters to 1,000 meters, from 1,000 to 10,000 and then 100,000, we’re still seeing Saturn and Mercury about the same height above the horizon, because that horizon is coming with us. Almost like a big bulge out of the Earth rather, than dropping away as the horizon would do if you were going up something much smaller. If you were going up a small elevator and you could still see the Earth’s actual horizon beyond it, then you’d see those elevations appear to change.

I was hoping to show the effect of double sunsets, getting an extra sunset by climbing very high in the sky very quickly, but unfortunately Stellarium does not seem to show that. It doesn’t seem to be able to show the horizon appearing to get smaller as you go higher up a point, it can only show what it would look like if you were actually at a higher elevation. That is useful, for example, if you were traveling to one of the big high up cities in the Andes and the Rockies, like some of the big cities in Peru, or even I suppose one of the higher parts of Colorado, and you wanted a preview of what it might look like. Given that this software does account for elevation to some degree, and it states the altitude in the description of the landscape where using, it is useful for representing the view of an area.

Locations in Stellarium come with listed heights in the location window as well. By aiming for somewhere tall, like up in the Himalayas, you are likely to see locations hundreds of meters above sea level. The Himalayas, with Mount Everest, are the highest place in the world, giving the highest elevations above sea level that you’re going to get. I don’t know which towns and cities of the region are particularly high, but compared to Ireland they’re all up high if they’re in this region. By clicking around in Nepal I was able top find a location 697 meters off the ground. This turned out to be the city of Birendrangar, which does seem to occupy a flat raised area, but in a very high valley rather than out on a plateau. However, it is still a flat-ish region kilometers across within a landscape of mountains and hills. It’s not going to be a perfectly smooth place with a flat horizon. That’s going to mean that you might not be able to see the horizon all the way around, there’s going to be mountains in the distance and other things up at this elevation with you. However, using this you can simulate the view up at 600 meters, it will give you an idea of when it will get dark for you. In this example, Saturn would be quite high at sunset, this is much closer to the equator, so of course the planets are going to look more kind of straight up in the sky.

Stellarium is not going to be able to show you the difference in view from the ground floor of the Burj Khalifa compared to the observation deck of the Burj Khalifa, because it’s not going to simulate the horizon sort of dropping away like that, but it does seem to be able to display some of the effects of your elevation changing, such as when you see the sunset and how the sky is going to look due to the thickness of the atmosphere. These are still interesting things to simulate, it’s nice to know that we can simulate the view for a weather balloon floating away above the location of Cork City. If we go way up to the highest heights simulated, we get the kind of view that a high altitude balloon would get, with the planets and the Sun in a almost blue sky. It’s interesting that it all gets simulated with the horizon staying the same, rather than the kind of elevation change you’d expect from a building or a narrow mountain.

That is a little bit on elevation and how Stellarium shows it, what ways this software is limited and how it relates to the horizon. I hope that you enjoyed this little piece, even though it didn’t really look at the thing that I originally wanted to look at, I hope that you still it interesting. If you did, please do like the piece and you can also subscribe to this website and my YouTube channel if you’d like to see more of my content. Hopefully, I’ll see you back here next time.