Science of Tatooine: Water
Written by Adrienne M. Roehrich, Manager of Editorial Services
In the Star Wars Universe, Tatooine is a desert planet with two suns.
According to the Merriam-Webster Dictionary(1) a desert is
1a : arid land with usually sparse vegetation; especially : such land having a very warm climate and receiving less than 25 centimeters (10 inches) of sporadic rainfall annually
b : an area of water apparently devoid of life
Clearly, definition b is not in effect for Tatooine, as there is megafauna. Merriam-Webster Dictionary(2) defines megafauna as:
1: animals (as bears, bison, or mammoths) of particularly large size
2: fauna consisting of individuals large enough to be visible to the naked eye
On Tatooine, there are krayt dragon, rancor, sarlaccs, dewbacks, banthas, among other animals. Our understanding of life requires water. On a planet with less than 10 inches of sporadic rainfall annually, how do such big animals get their water?
We have to move outside of Universe canon to consider water on Tatooine. (Canon, as of the summer of 2014, has been declared to only include the six movies to date and the Clone Wars television series.) So, there is little to go on. Some of the books, outside of canon, discussed Tatooine as a planet much like earth with large oceans that was altered by an alien race. Whether a planet with suns such as Tatooine could have the described oceans, is another article. However, it does help with how the animal-life could have evolved. Another question arises: in such a change of climate, how did these animals adapt? (Peruse the carnival for an answer to this question!)
One possible source of water includes the very dry atmosphere. Water vapor occurs in the atmosphere, even those above deserts. Relative humidity varies from region to region. On a planet entirely desert, this could be true as well. Not all deserts have the same atmospheric humidity.
Luke Skywalker is introduced on the moisture farm of his aunt and uncle. These moisture farms use a technology called moisture vaporators. Moisture vaporators condense water out of the atmosphere using cooling rods. This works much like a cold beverage getting condensation on the outside of it on a hot day. Water vapor from the atmosphere comes into contact with a cooler surface and condenses. In a fairly humid region, this will happen at temperatures near current temperatures. However, in the desert, the temperature at which the water will condense is lower. Once condensed, the water flows down the rod into a water storage tank. Clearly having working vaporators is a matter of survival for humanoids on Tatooine. Indeed, a moisture farm is necessary to provide water to bigger cities. No wonder Owen Lars requires a droid with translation skills.
“What I really need is a droid that understands the binary language of moisture vaporators.”
“Vaporators? Sir, my first job was programming binary loadlifters—very similar to your vaporators in most respects.”
from A New Hope
Another possible source of water on this desert planet is aquifers. Aquifers are a water-bearing stratum of permeable rock, sand, or gravel(3). Aquifers are often linked to rivers. With the evident geology of Tatooine in the various movies, one can guess that at one point there were rivers flowing on Tatooine. In fact, the Sahara Desert on Earth, has seasonal and intermittent rivers, lending credibility to the possibility of the same on Tatooine. Some of the cities on Tatooine could also get water piped in from existing aquifers in the region.
Obviously, the non-humanoid animals are not using these moisture farms to gather water out of the atmosphere, nor are they digging their way down to the potential aquifers. So how are they getting their water? What other sources could they get for water?
Animals that have evolved to survive and thrive in desert climates may not need to consume water the way we think. Many desert animals retain water using methods such as burrowing into moist soil, and some do not excrete it the way mammals do. Often, due to water retention and evolution to need less water, they are able to get all the water they need through the vegetation (or animals) they eat. As we can see from the aquifer diagram, it is these underground sources of water that lead to the small oasis of vegetation. In addition, groundwater will come to the surface to create little pools, which animals can gather at to consume water.
Sources of water on this desert planet may be sparse but they exist.
Be sure to visit all the posts in this Science Carnival!
Science of Tatooine: Water – Adrienne Roehrich
The Limits of Animal Life on Tatooine – Maggie Koerth-Baker
- Tatooine’s tangled bank – plants evolve in a galaxy far, far away — Malcolm Campbell
- Diary of an Interplanetary Naturalist – The Sarlacc — Joe Hanson
1. “Desert.” Merriam-Webster.com. Accessed July 20, 2014. http://www.merriam-webster.com/dictionary/desert.
2. “Megafauna.” Merriam-Webster.com. Merriam-Webster, n.d. Web. 20 July 2014. <http://www.merriam-webster.com/dictionary/megafauna>.
3. “Aquifer.” Merriam-Webster.com. Merriam-Webster, n.d. Web. 21 July 2014. <http://www.merriam-webster.com/dictionary/aquifer>.
4. Desert USA http://www.desertusa.com/survive.html