Both Uranus and Neptune are the ice giants in the outer location of our solar system. Uranus is 1.784 billion miles from the sun. This means that Uranus and all of its satellites receive some of the lowest sunlight of all of the planets.
Of Uranus’ 27 moons, Miranda has the closest orbit of the five largest moons and it’s very small. But size isn’t the only notable feature about Miranda. With a diameter of around 293 mi/471 km, Miranda has been called the “Frankenstein” of moons because its appearance is so strange. If you look at this moon you would think that someone took a lot of pieces and parts and just jammed them together. Miranda is the eleventh moon in orbit around Uranus and is the fifth largest of all of the moons rotating around Uranus.
Miranda is a sphere of rock and ice with an incredibly strange landscape. Researchers have been curious about Miranda for a long time and now think that they know why the moon is so bizarre. Scientists think that the influence of the gravity of Uranus on Miranda has caused a constant state of stretching and squeezing so that Miranda’s internal contents are in a steady state of heating up and churning.
The landscape of Miranda includes a lot of deformities and extremes, and is the most unusual among all of the extraterrestrial objects. While it is only one-seventh the size of our own moon, Miranda has huge canyons that are twelve times deeper than the Grand Canyon, and scientists have called this moon exotic and beautiful. Researchers have indicated that Miranda’s small size doesn’t support the ability to have much in the way of tectonic activity, and yet the landscape has the appearance one that has an intense internal energy.
- Orbits: Uranus
- Discovered By: Gerard P. Kuiper
- Discovery Date: February 16. 1948
- Diameter: 471.6 km
- Mass: 6.59 × 10^19 (0.09% Moon)
- Orbital Period: 1.4 days
- Orbit Distance: 129,900 km
- Surface Temperature: – 213 degrees C
Astronomer Gerard P. Kuiper discovered Miranda while at the McDonald Observatory in Texas on February 16, 1948. Miranda was the last moon orbiting Uranus to be found before the launch of the 1986 Voyager 2 spacecraft.
Miranda was given the name of the Prospero’s daughter from the William Shakespeare play, “The Tempest.”
Formation, Structure and Surface:
Miranda has three large features that are called “coronae,” and these are fairly unique in the solar system. Their shape is kind of like a crude oval or trapezoid. The coronae are collections of valleys and ridges that have a sprinkling of craters and are separated by heavier and potentially older cratered terrain. Each one is around 120 mi/200 km wide. This creates patches on the surface that are mismatched with sharper boundaries that lead into giant canyons. These canyons are as deep as twelve times the depth of the Grand Canyon.
Miranda’s surface has an appearance of mismatched patches. Separating the coronae are concentrated belts of troughs and ridges that are highly crated. The names of the three corona are from places in Shakespeare’s play: Arden, Elsinore, and Inverness.
Scientists continue to study Miranda to try to figure out how it was formed and what has caused its unusual landscape. Some feel that at one point in its history, Miranda could have been involved in a horrific collision that caused it to become shattered and then it later came together to be reassembled in such a strange way. Another theory that is more popular is that the coronae are actually locations of large metallic meteorite and rocky hits that affected the subsurface ice by partially melting it. This would have created variations of water with a slushy consistence that may have arisen to the surface, causing the surface to crumple as the water refroze. This may have happened early in Miranda’s formation as it is a small moon and would have cooled quickly. There isn’t any radioactive material to maintain heat in the subsurface.
Continued study of Miranda has offered additional information that shows that the gravitational pull from Uranus could have pulled and pushed Miranda enough to cause heating inside of the moon. It’s known that Uranus’ gravity does generate tidal forces in the same way that our moon does to our planet. Scientists have seen that tidal forces that exist on other objects in our solar system are a lot bigger than those of Earth. The effect of the forces also depend on the composition of the object being pulled and pushed. In the case of Miranda, it’s believed that it’s made up of mostly equal parts of silicate rock and water ice, which would be easier to manipulate than a higher percentage of rock. However, it also depends upon the gravitational pull of the planet. In the case of Jupiter, which has an enormous gravitation pull, it can cause solid rock surfaces of Io to bulge out as much as 300 ft/90 m, which in turn, is the engine that heats up the interior to cause volcanic eruptions.
The brightest of the moons around Uranus is Ariel, and Miranda has a surface that is almost as bright as Ariel. However, none of the moons reflect more than around 1/3 of the light from the sun that hits them. Scientists believe that the reason for this low reflectivity is that some of the surfaces have carbonaceous material that darkens and absorbs the sunlight.
It has been noted that when Miranda is in “opposition,” there is a dramatic increase in the brightness. Opposition is a situation where the viewer is directly between the sun and the object (Miranda). Researchers explain that this condition indicates that Miranda has a porous surface, casting reflectivity-decreasing shadows when other angles illuminate it. Some assume that this condition could be due to hundreds of thousands of years of strikes by micrometeorites causing the top soil to be constantly disturbed.
Miranda once had an oval-shaped orbit that is called “eccentric.” However, over time, Miranda moved closer to Uranus and the orbit changed. Researchers have created three-dimensional computer simulations of the interior of Miranda for more extensive studies on the effects of the tidal forces as it stretched and squeezed the moon. The goal was to see if these tidal forces would be enough to generate the kind of heat needed. Researchers have figured out that it would require around 5 gigawatts or 2.5 times the top output of the Hoover Dam that is on the Colorado River a to cause the icy mantle to churn and then create the condition for ice to be buoyant enough to rise to the surface, contort it, and create the coronae.
The results of the computer models did accurately explain where the coronae forms and its deformation patterns. This type of heating process is known as “convection,” but scientists have recognized that if this was the main cause of the creation of the coronae, Miranda’s surface had to be weaker than what was used in the laboratory experiments. Geologists see the same situation on Earth. For convection to be successful on the surface of Earth, the rocks have to be a lot weaker than expected.
Atmosphere and Magnetosphere:
Miranda has no detected atmosphere or magnetosphere.
Could Life Exist?
Miranda doesn’t have any of the requirements needed to begin or sustain life as we know it.
- Miranda has an odd appearance, looking more like puzzle pieces that were mismatched and jammed together so that they don’t fit.
- Miranda’s surface has a younger appearance with a lot of past activity.
- The coronae on Miranda have very few craters but do have a lot of valleys and ridges. There seems to be a defined boundary that separates the cratered terrain.
- Miranda is a small moon and yet it has canyons bigger than those found on Earth.
- Verona Rupes is the highest cliff in the solar system and stands up to 20 km high.
- Scientists don’t seem to be able to come to an agreement on how the features of Miranda were formed.
- Miranda holds the distinction of belonging to some of the smallest objects in the solar system that has been able to use its own gravity to become spherical.
- Miranda shares the same cycle of extreme seasons as Uranus due to the tilt of its parent planet.
- Miranda may be left over material from the formation of Uranus billions of years ago.
The NASA Voyager 2 spacecraft took images of the southern hemisphere of Miranda in 1986 during its flyby of Uranus. The spacecraft didn’t get images of the northern hemisphere.
There are currently no plans for any other visits to Miranda.
Facts about Miranda Moon for Kids:
- Miranda is mostly made up of ice and may have some material closer to the core that is rock.
- Miranda has a surface topography that baffles scientists. No two areas are alike and the surface has just about everything from craters to cliffs.
- Scientists think that Verona Rupes, the largest cliff on Miranda and in the solar system, may have been created when there was a fault in Miranda’s surface causing a crack and part of the surface to collapse and drop.
- One of Miranda’s coronae has a feature in its center that looks like a “checkmark.”
- Miranda is also called the “patchwork moon” because of its strange surface.
- Miranda is tidal locked to Uranus so only one side of the moon ever faces the planet.
- NASA didn’t have a choice in sending Voyager 2 close to Miranda because it needed to flyby to get the boost that was required to head to Neptune.
- Miranda was never assumed to have much to offer scientists and it wasn’t until Voyager 2 sent back the images of the moon that they realized that it was more remarkable than they would have ever guessed.
- Miranda’s surface is unlike anything else that has been found so far in our solar system.
The novella by G. David Nordley from Analog Science Fiction entitled “Into the Miranda Rift” was set on Miranda.
Doug Naylor and Rob Grant wrote the novels based on their sitcom Red Dwarf. In the novels, Miranda is a huge and crowded spaceport where a main character decides to take a vacation when his girlfriend dumps him. He adopts a cat that is named Frankenstein.
Kim Stanley Robinson’s 1997 Blue Mars includes two characters that visit Miranda. The moon is in the process of being preserved as a primal wilderness by Uranian system colonists. Some of the other moons of Uranus are being colonized through the use of fusion lanterns in the upper atmosphere of Uranus so that there is additional light.
The musical group Pink Floyd created the 1967 song Astronomy Domine and has a line in the song that mentions Miranda.
The computer game Descent’s level 18 occurs in a mine on the moon of Miranda.