Extraterrestrial Hide and Seek
What are the odds of seeing something that doesn’t want to be seen?
Let’s assume that, for whatever reason, an off-world intelligence wanted to come visit. Could they do that without being seen? Long before you wade into a conversation about stealth technology or hypothetical cloaking devices, you’ll find that a simple look at our planet makes this an obvious “yes.” From time-to-time, commenters in the UFO space will express this sentiment by pointing out that “the oceans are big” and there’s “plenty of places to hide” but I think this conversation could really benefit from a sober look at the data.
Today, I want to take you on a brief walkthrough of our planet and really illustrate for you how unlikely it is that anyone would see a UFO, ever. The fact that we do, and that there are reports in almost every geographic location raise some good questions about how many might be out there, and where. To start:
The Earth has 510,072,000 km2 of surface area.1
70.8% of this area (361,132,000 km2) is covered by ocean.2 These oceans are:
27.0% (137,926,515 km2) territorial waters,3 which are the waters that extend off the coastline of every major country on Earth. The first 22km are called a country’s “territorial sea” and, after that, they can make a maritime claim extending a further 370km past that point. The territorial water held by any one country depends on where it is, what its claims are, and if those claims conflict with anyone else.4
It's important to consider territorial waters because they are the most likely to host local maritime traffic. So, with that in mind, let’s consider a scenario where the most common form of that traffic (fishing boats) were all out, everywhere on Earth, at the exact same time. Assuming the weather was clear (it wouldn’t be), visibility was clear to the horizon (that’s unlikely), and that clarity produced a 20km2 box of human sightline (lol!), you’d be able to cover about 59% of these territorial waters on any given day.5
Of course, people sleep, pay attention to their work, and are denied basic visibility by weather conditions at sea, and so the most common circumstances result in this area being largely unmonitored, even with an estimated 4.1 million fishing vessels all over the world.6
A further 43.8% (223,205,485 km2) of the ocean is international waters.7 These waters are so far away from major countries as to basically be unmonitored. It’s hard to get a sense of how vast some of these areas are but the Pacific Ocean, which holds 43% of all of the water on Earth, could fit the United States into it 17 times.8
Here, the most likely traffic are commercial cargo ships. With a global fleet of 50,000, we can again consider a scenario where each one produces a perfect 20km2 box of human sightline and where every single cargo ship on Earth happens to be in international waters at the same time.9 And in that scenario, you’d be able to cover about 0.4% of all the international water on Earth, with human sight.10
But, of course, the actual coverage of cargo ships is even worse than this thought experiment might imply, because, unlike the sporadic sailing of a fishing boat, cargo ships travel in well established sea lanes. These “highways of the sea” basically take them across very predictable, linear routes which make them very easy to avoid and further reduce the coverage of this huge chunk of the earth.11
The surface area of the ocean doesn’t do the problem justice because, below that surface, we have to consider how deep those oceans go. Accounting for all of that sub-surface water produces an area of 1.370 billion km3.12 Given the frequent reports of UFOs travelling within and emerging from the Earth’s Oceans, this is actually the most likely place that something exotic would travel if it was seeking to avoid human contact.
What are the odds of detecting anything under the surface? Here we can consider the only vehicles that would have that capability, the military vessels of the world’s combined naval fleets. With 10,525 naval vessels including 505 submarines,1314 all of the naval forces in the entire world would struggle to cover any significant portion of the world’s oceans. Of course, when dealing with military equipment, you stray into the realm of sensor assistance, but even the best Sonar, for example, has a range of about 48 km when actively scanning for targets. So assuming every submarine on earth could take an active approach to scanning under the ocean, they could cover about 4% of it at any one time.15 And that’s not even taking into account the depth limitations of most submarines. All the other naval assets would be limited by their position on the surface and their tendency to stay grouped near the shores of their home country.
Leaving the Ocean, we now turn to the remaining 29.2% (148,940,000 km2) of the Earth’s surface that is covered by land.16 Of this landmass:
8.5% (43,192,600 km2) is uninhabitable.17 This includes glaciers, deserts, dry salt flats, beaches, exposed rocks, and all other places where humans are extremely unlikely to be.
20.7% (105,747,400 km2) is habitable land. This consists of:
Forest or Jungle (7.9%)
Livestock, Meat, and Dairy Production (7.3%)
Unused Shrub and Grassland (2.9%)
Agricultural Crops (2.2%)
Human Settlement and Infrastructure (0.2%)
Freshwater Lakes and Rivers (0.2%)
As you can see, once you leave the shockingly small percentage of our planet that is settled by human beings (0.2%), you find yourself dealing with portions of our landscape where human presence is pretty unlikely. What are the odds of you being in the right farmers field at the right time? (9.5% of the planet) How about the wilderness? (11%). There’s no need to speculate on vehicle traffic or military presence in these areas. The sheer volume of hiding places, even in this “habitable” section of the world, make that pretty much irrelevant.
As a final consideration, we turn to the air above us. 99% of our atmosphere exists within 40km of the Earth’s surface,18 and, taking into account this “atmosphere we care about” we can calculate a volume of 20.530 billion km3.19 Taking into account the highest estimate for the total number of airplanes in the world (passenger planes, cargo planes, and military planes) we come to a number of 39,000.20 If we assume that every single airplane was flying at once, and that every single pilot had a clear visibility of 10km in every direction, we’d be able to cover about 1.5% of the sky at any one time.21
The real world crashes into this estimate as well as there are only about 16,000 airplanes in the air on any given day and, like cargo ships, they travel on very predictable (easily avoidable) major air routes.2223 All but the most advanced military craft would be limited to the lower parts of the atmosphere, and this is to say nothing of the difference between day and nighttime visibility or cloud coverage. Here again, we see the most optimistic scenario really isn’t that optimistic. At the end of even our most hypothetical of days, the sky remains a big place with plenty of places to hide.
So do you need to believe in extremely advanced stealth technology to consider the possibility of covert extra-terrestrial visitation? Not really. And if up until now, you’ve been under the impression that we would almost certainly see anything strange travelling around, well … you might have a blind spot.
P.S. This article tries to add something new to a long-running convo. Do you know someone who might benefit from the data offered here? If so, then please:
Pidwirny, Michael, and Scott Jones. “CHAPTER 8: Introduction to the Hydrosphere (o). Introduction to the Oceans.” Physical Geography at University of British Columbia Okanagan, April 6, 2010. http://www.physicalgeography.net/fundamentals/8o.html.
Note: There are many conflicting estimates of the exact surface area of the Earth. I’ve chosen this estimate as it’s the preferred citation used on Wikipedia.
Pidwirny, “CHAPTER 8: Introduction to the Hydrosphere.”
Pauly, Daniel, Dirk Zeller, and Deng Palomeres. “Data Drawn From EEZ Search.” Sea Around Us at University of British Columbia and the University of Western Australia, 2020. http://www.seaaroundus.org/data/#/eez.
Note: This data forms the basis of this table on Wikipedia, which I pulled the total from.
“United Nations Convention on the Law of the Sea.” The United Nations, December 10, 1982. https://www.un.org/depts/los/convention_agreements/texts/unclos/unclos_e.pdf. Pg 27, 44.
Note: This calculation was made on the assumption that a human being can see unassisted until the curvature of the Earth at 3.1 miles (5km), resulting in a 20km2 range of vision, multiplied by an estimated 4.1 million fishing vessels on Earth. The result is 82 million divided into the 137.9 million km figure for territorial waters, producing a potential coverage of 59.45%.
“Estimate of the Global Fleet and Its Regional Distribution.” Food and Agriculture Organization of The United Nations, 2020. https://www.fao.org/3/cc0461en/online/sofia/2022/fishing-fleet.html.
Note: The 43.8% figure and the precise coverage in km2 was calculated by subtracting the total ocean coverage from the total EEZ coverage in Endnotes #1 and #3.
Note: Calculated with the Pacific Ocean figure from Pidwirny (155,557,000 km2) and the widely available estimate of U.S. land mass (9,147,420 km2).
“Shipping and World Trade: Global Supply and Demand for Seafarers.” International Chamber of Shipping, July 2021. https://www.ics-shipping.org/shipping-fact/shipping-and-world-trade-global-supply-and-demand-for-seafarers/.
Note: This calculation was made on the assumption that a human being can see unassisted until the curvature of the Earth at 3.1 miles (5km), resulting in a 20km2 range of vision, multiplied by an estimated 50,000 cargo ships on Earth. The result is 1 million divided into the 223.2 million km figure for territorial waters, producing a potential coverage of 0.44%.
Plummer, Brad. “This Is an Incredible Visualization of the World's Shipping Routes.” Vox, March 22, 2017. https://www.vox.com/2016/4/25/11503152/shipping-routes-map.
Pidwirny, “CHAPTER 8: Introduction to the Hydrosphere.”
“Navy Fleet Fleet Strength by Country (2023).” Global Firepower, 2023. https://www.globalfirepower.com/navy-ships.php.
“Submarine Fleet Strength by Country (2023).” Global Firepower, 2023. https://www.globalfirepower.com/navy-submarines.php.
Note: This calculation was made on the assumption that active sonar is accurate in ideal conditions at about 30 miles (48km), resulting in a 110,592km3 box of vision, multiplied by an estimated 505 submarines on Earth. The result is 55.8 million divided into the 1.37 billion km figure for ocean volume, producing a potential coverage of 4.07%.
Pidwirny, “CHAPTER 8: Introduction to the Hydrosphere.”
Ritchie, Hannah, and Max Roser. “Global Land Use for Food Production.” Our World in Data, September 2019. https://ourworldindata.org/land-use#:~:text=10%25%20of%20the%20world%20is,we%20call%20'habitable%20land'.
Note: This source provided square kilometer figures and percentages that are rounded and do not sum. I’ve worked backward from the percentages provided by multiplying them into the known land coverage figure from Pidwirny. All of the percentages and kilometer figures in this section are derived from those calculations to provide the most accurate (and congruent) assessment possible.
Manahan, Stanley E. “8.3: The Atmosphere.” Libre Texts Chemistry, March 16, 2021. https://chem.libretexts.org/Bookshelves/Environmental_Chemistry/Green_Chemistry_and_the_Ten_Commandments_of_Sustainability_(Manahan)/08%3A_The_Five_Environmental_Spheres_and_Biogeochemical_Cycle/8.03%3A_New_Page.
Travelweek Group. “Exactly How Many Planes Are There in the World Today?” Travel Week, February 17, 2017. https://www.travelweek.ca/news/exactly-many-planes-world-today/.
Note: This calculation was made on the assumption that, at a higher altitude, we could double a human being’s effective vision from 5km (in the ship-based assumptions) to 10km. This creates an 8000 km3 box of vision, multiplied by an estimated 39,000 airplanes on Earth. The result is 312 million divided into the 20.530 billion km figure for atmospheric volume, producing a potential coverage of 1.51%.
Travelweek, “Exactly How Many Planes Are There in the World Today?”
Myers, Joe, and Rosamund Hunt. “This Visualization Shows You 24 Hours of Global Air Traffic – in Just 4 Seconds.” World Economic Forum, July 12, 2016. https://www.weforum.org/agenda/2016/07/this-visualization-shows-you-24-hours-of-global-air-traffic-in-just-4-seconds/.