Here’s a hypothetical situation. Imagine we got visited by aliens who came from another star system. Not to conquer us or to share their secrets. Instead, imagine they just came as tourists visiting our Solar System. Now, here’s a question. What should we show them as our best tourist attraction?
What Is a ‘Good Tourist Attraction’
Let’s start with making our definitions clear. Every good tourist place has some kind of place of interest or an attraction. It is usually something unique for this particular place that you can’t find anywhere else. It might be a landscape phenomenon, like a mountain or a waterfall. It might be a natural phenomenon, like a forest or a habitat for a certain species. It can be an artificial thing that has some significance, like a cool architectural creation or a thing with some historical significance to it.
So, when it comes to choosing a tourist attraction within our Solar System, it has to be something that the visiting aliens don’t have at home, whichever planetary system they came from. Something they definitely didn’t see in other places they could have visited in the Universe.
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Of course, we all understand that bringing aliens into this is just a bait that makes any story more interesting by engaging with your imagination. But the real question here is not that funny or hypothetical. It actually makes a lot of sense and is rather important for Astronomy.
If we take away the ‘alien factor’, the real question we’re trying to find an answer to is the following:
Now, when we have the rules of the game established and all the definitions sorted out, let’s explore the options that we have.
The first thing that probably comes to mind is biological life. After all, that is what defines our place in the vast emptiness of the Cosmos. We don’t see any evidence that life as we know it exists anywhere else. That is what the Fermi Paradox is all about.
But, with the rules of the game we just established, this point kind of eliminates itself. If there are alien tourists coming from somewhere else, it automatically means that life also exists elsewhere. Meaning that our guests won’t be impressed by just the fact that we have life. Meaning that we need to come up with better ideas.
However, we should not completely write life off as a factor. It is quite possible that the biodiversity we have at our disposal can be quite extraordinary. Even if life could exist in other places of the Universe, there are no guarantees that it would be so rich for all sorts of species. So, the number of different lifeforms and the branches that life did evolve to can be a tourist attraction of its own.
But as we agreed to play the alien game here, let’s not stop here and look for other options.
Rings of Saturn
Saturn with its vibrant rings that can literally be seen from millions of kilometres away is probably the next thing that comes to mind when thinking about a defining feature of our Solar System. They are truly magnificent. Of course, other giant planets also have their own rings. Even Earth might have rings at some point in its history. And Mars should destroy Phobos with tidal forces and turn it into a nice set of rings relatively soon on a cosmic timescale. But even taking all that into account, Saturn rings still look outstanding.
Unfortunately, it might not impress our alien guests at all. At this moment we know about 5000 confirmed exoplanets. It’s a very small sample compared to the real number of worlds that are out there. But even among this small sample, we know about a planet called J1407b.
This planet orbits a relatively nearby star, only 430 light-years from us. But the biggest bummer for us is that it is estimated to have a set of rings 200 times bigger than Saturn’s. This means that ring systems aren’t rare among exoplanets and can easily go much more extreme than what we have in our Solar System. Thus showing our alien guests Saturn for its set of rings would be like showing a three-storied building in a village to people who came from New York, Dubai or some other place full of skyscrapers.
Cool Looking Storms
How about the Great Red Spot on Jupiter then? Or maybe other really cool storms on the gas planets, like the polar hexagon on Saturn, the Great Dark Spot on Neptune or the arrangement of storms on Jupiter’s poles. They could be a great thing to show to visiting alien tourists, right?
However, in reality, they are just weather patterns that should inevitably emerge on any gas giant. And we know that there are a lot of gas giants out there that can be much more extreme than Jupiter, Saturn, Uranus and Neptune. Meaning, that it’s exactly the same catch we had with the rings of Saturn. They might look really impressive to us, but they are very average for anyone who has been to a number of other planetary systems.
Water on Earth
Maybe we should be looking at Earth then? For sure, there is something unusual that can be found here. For example, you could notice that the conditions here allow all three main states of matter to exist. We have water vapour in the air, we have liquid water in the oceans and we have water ice on the poles and mountain caps. Pretty cool, right?
Of course, having water in all three different states on the surface is one of the key ingredients for life. But it might not be as outstanding of a feature as we think at first. We have evidence that at some point same thing occurred on Mars and quite possibly Venus. And even now we have Titan, which is another place that has all three states of matter: gas, liquid and solid. Instead of water, it’s hydrocarbons like methane, but the defining feature is there. Meaning that, if it’s not unique even just within our Solar System, it’s definitely not unique in the rest of the Universe.
Maybe It’s Something We Lack
So far we’ve been looking at something that our Solar System has, so we can use it as a tourist attraction. But what if we need to think outside of the box instead? What if it’s about something we don’t have rather than something we have?
Some really cool research has been done on this topic. For example, here’s a great paper called The Solar System as an exoplanetary system by Rebecca G. Martin and Mario Livio. It tries to look at us as if the Earth and the rest of our planetary system were studied as an exoplanetary system and how we would compare to other ones that we know about today.
There are some interesting findings that make our Solar System somewhat unusual. Particularly, it’s about us a lack of super-Earths (rocky planets larger than Earth and smaller than Neptune) and a lack of bodies orbiting the Sun within the orbital radius of Mercury. Of course, studies like that are based on our current selection of exoplanetary worlds, which is definitely biased due to our instruments and detection methods. But still, it gives us at least something that we can potentially stand out with. Or rather ‘stand out without’.
It Was Hiding in Plain Sight
So far we didn’t find any outstanding feature that would make our Solar System stand out from the rest of the Universe. It probably makes sense, as that is exactly what the Cosmological Principle tells us. No place in the Universe is special on a large scale. But I still think that there’s one astronomical feature that might be unique enough to make a good tourist attraction for any aliens visiting.
It’s been hiding in plain sight all along. It’s something that we are used to enough that we don’t even think about it as an unusual feature.
For a tourist attraction to be unusual, there has to be some sort of lucky coincidence. The one I’m referring to is the fact that our Moon is almost exactly 400 closer to us than the Sun and at the same time is 400 smaller than the Sun. As a result, the angular size of the sky when looking from the surface of Earth is practically identical.
All this leads us to the fact that the total solar eclipse we are witnessing here on Earth might be the exact spectacle we were looking for. If the satellite appears to be bigger than the star in the sky, an eclipse is just like a nighttime event. If it’s smaller, it’s just a boring transit that most won’t even notice. Here’s an example of the latter captured by the Perseverance rover earlier this year.
The eclipse on Earth is different. When the Moon meets the Sun in the sky they match so well that you often can see the Sun’s corona. It’s hard to not notice a total solar eclipse. At the same time, we can be quite sure that a coincidence like that doesn’t occur that often in other planetary systems. Meaning that an experience like that would be equally unforgettable for someone coming from another star system, as it would be for an earthling.
Unfortunately, it won’t last forever. The Moon is slowly moving away from us. At some point it will become smaller in our sky and eventually it will go into a full tidal lock, meaning that it will be visible only from one hemisphere of the Earth. So, those alien tourists better come quickly to visit while it still lasts.
More Thoughts Like That
Originally I did this idea for a video on my channel, so if you like topics like that, consider checking out my other stuff on YouTube.
Of course, these are just my thoughts on the topic. If you have other suggestions about what we should be showing to tourists from other planets, let me know about them. I believe it’s an interesting thing to think about which can give you a good perspective on our true place in the Universe.