Caoimhín's Content

I’ve mentioned the planets quite a lot recently, and with good reason. Over the course of the month of August, particularly in the morning, there are going to be a lot of planets in the sky. Even early in the month we have Jupiter, Mars and Saturn all together in the sky. If you caught a few of my recent pieces, then you’ll know that Uranus is up as well, close to Mars and the Pleiades, as well as Neptune just a little East of Saturn. As we come through to the end of the month, Mercury will also be visible at sunrise, putting 6 planets in the sky all together.

Of course there is one more planet, Venus. If we could see the Sun and the planets together, looking at a sky with no atmosphere to light up blue, then we would be able to see Venus. It’s not directly in line with the Sun, in fact Venus is clearly East of the Sun by a reasonable amount. With no atmosphere, we can just about see the Sun setting while Venus is still, just barely, above the horizon. With the horizon I usually use for the simulated sky, there is a reasonably big tree almost directly in the West, but the bright disc of Venus can be seen through it’s branches, as long as the atmosphere is turned off at least.

It may seem inconvenient to have a big tree on the horizon, and it is, but this is realistic. There are very few locations on Earth where you will get a perfect flat horizon the whole way around, there will almost always be some part of the sky obscured by a hill, building or other obstruction. Thankfully, we are not limited by realism in Stellarium. You may remember from older articles that we can look at the sky from the upper atmosphere of Saturn, or see the solar system from the Sun’s perspective. We can of course with a hypothetical perfectly flat horizon. The minimum horizon caused by the Earth’s curvature, no buildings, no trees, nothing else to get in the way. With this perfect view, we can see when the Sun is under the horizon, Venus is still above it. Once I turn back on the atmosphere, from here in Ireland at least, you may just about see a bright dot for Venus, but very low in the sky and swamped by the light of the sunset. As with all things, you would have a slightly better view in countryside, but it is still very very difficult. It will get easier and easier as we move through the month. As we push later in the year, Venus may appear lower at a given time, but it is setting early for the same reason the Sun is, our axial tilt. It will still be moving away from the Sun in our sky during this time, which is going to give it longer in our sky each evening.

Moving back to a more realistic, less perfect, horizon, the landscape used in Stellarium is a real location in France, Guéreins. The Beaujolais Mountains are visible in the background, putting this location within the region where Beaujolais wine is produced. The horizon this provides isn’t perfect, but it is quite a low horizon, there’s only a few little distant hills, and the big tree. Even still, Venus is so low that it is still pretty much completely blocked. This was a problem for Mercury when Mercury was visible in the evening as well. It was very difficult to spot from here in Ireland, partly because of the angle of the ecliptic. From more Northern latitudes, the ecliptic appears to cross the sky along the South, often forming quite a narrow angle with the horizon in the East and West. This keeps planets that are technically far from the Sun in the sky close to the horizon, and closer to the glow of dawn and dusk. This issue less of a problem closer to the equator. The closer you are to the equator, the higher the ecliptic will cross the sky and the wider the angle it forms with the horizon. We’ll start by going far to the South for here in Europe, down to about 36 degrees North. This isn’t particularly far South in the grand scheme of things, but it is a lot closer to the equator than Ireland at about 52 degrees North. This new latitude is just around the southern coasts of Spain and Portugal, and more broadly along the Mediterranean Coast. This also brings us to the latitude of the middle of the United States, and the same latitude of many countries in Central and East Asia, just below the Russian border, including Central China. Still a bit far North to get into South or Southeast Asia, but this is definitely closer to the equator. This also means there’s not going to be as drastic of a difference between the times of sunset and sunrise between summer and winter, closer to the equator there is less seasonal variation in day length.

The change in location brings Venus comfortably above forgiving simulated horizon, but if you’re deep in the bottom of a valley or surrounded by tall buildings or trees, even quite close to the equator those obstructions can still make Venus difficult to catch. Bring ourselves back to the start of August, we’re going to have to push later into the night. As we are moving backwards in time here towards summer, the sunsets will get earlier and earlier, meaning we’ll have to push later for darkness. Early in the month, Venus isn’t going to be visible quite as high in the sky, but even in the first week of August, Venus is above the horizon once you’re down to this lower latitude. Moving on towards morning time, the planets visible from Ireland will of course remain visible, and they could look a little bit more impressive from lower latitude as well. They will be visible a little earlier in the night and they will be higher in the sky under a good level of darkness, which is very useful if you are taking a closer look. This will also bring Mercury into the sky that little bit earlier, but we still need to be close to the end of the month. Mercury should become visible a little earlier in the month, but only by a day or so compared to here in Ireland. Even then, it remains just barely visible. Mercury is going to end up stretching out further from the Sun once we move into September, but I will talk more about that then. it is at least possible to Mercury for a little bit longer if you’re that close to the equator. Jupiter and Mars, as I mentioned, will be lovely and high in the sky as will Saturn, but being closer to the equator matters more for observing planets that are close to the Sun in the sky. Venus and Mercury will always be planets that are close to the Sun in the sky, unlike the more distant planets we can never see either of them on the far side of the Earth from the Sun.

We will take another hop closer to the equator, down to around 16 degrees north. We are still a few degrees North of the Equator here of course, but this does bring us down past the Southern United States into Central America, close to the latitude of Central India and the northern part of Southeast Asia. If you are a human living on this planet Earth, statistically you’re living in some of the higher populated areas. Over course, readers of my website and viewers of my channel are not a perfect representation, being potentially skewed by English. However, the view from these more Southern latitudes should hopefully cover a large portion of the human race in terms of what they are going to see. We will yet again come back to the beginning of the month and the beginning of the night. Now that we are just a little bit off of the equator, the angle at which we’ll see the ecliptic, and thus the planets, will be a lot closer to a right angle. This will be true whether you’re 16 degrees North or 16 degrees South, though you will see the planets a little South or North of the point of sunset, depending on what hemisphere you are in. From here, Venus is visible for a reasonable stretch of time in the evening. It starts to come up just as we come up to 6:40, and it stays visible right up until about 7 o’clock. This gives a full 20 minutes with Venus in the sky, even at the beginning of the month. Once we start moving later in the month, it will still be there as the sky is getting reasonably dark, so by the end of August, Venus will be a reasonable target for a telescope, you’ll have sufficient darkness, if you are at a low enough latitude. By the end of the month, Venus should be visible by just 6:20 from lower latitudes, and it will stay above the horizon until the sky gets quite dark, until at least 7 o’clock, a full half an hour with Venus visible in the sky. This is with a low but imperfect horizon. Returning to the hypothetical, perfect, zero horizon, Venus is still visible until almost 7:30, about an hour with Venus in the sky.

The zero horizon is of course simulated, perfect, flatness, something which is difficult to achieve in real life. If you were standing on a big enough salt plain or salt flats perhaps, but even in the largest salt flat in the world, hills are visible along the horizon. Hills may be a little unfair, as some of the mountains visible from Uyuni salt flat in Bolivia are part of the Andes mountain range. Floating in the middle of the ocean, with no land around you, would make this achievable, but of course, that’s a pretty extreme circumstance to be in. Moving around to morning time, we continue to see Saturn, Jupiter and Mars, now approaching the Zenith when they are at their highest. Late in the month, Mercury will start to come up as well. If you truly have nothing blocking your horizon, Mercury can be visible as early as 5:00, but being so low in the sky will make it fainter and harder to spot. it will rise as the Sun does, continuing to stay visible until just 5:15. This length of time would be extended from the countryside, but it is pretty brief even then. When it comes to the smallest planet in our solar system, it doesn’t matter too much where you are, Mercury’s going to be pretty tricky to see. It will never be very far from the Sun in the sky, even if it gets further form the horizon closer to the equator. get too far from the Sun. For Venus at least, if you are in a different location to Ireland you may be in with just a slightly better chance of getting to see it. The planet Venus will be the Evening Star for August, the very first thing to appear after sunset, the brightest thing we see in the sky besides the Sun and the Moon.

I hope some of you from lower latitudes enjoyed my description of the sunset Venus in August as you will see it, while I will not. If you are going on holidays form Northern latitudes, if you’re trying to escape the coming autumn by migrating South to warmer climes, then that might bring Venus into your sky as well. If you’re staying in the northern latitudes, at least you now know why you’re not getting to see Venus at the moment. If you enjoyed this piece and would like to see more from me, do consider subscribing to my website and YouTube channel. Hopefully, I’ll see you back here for my next piece soon.