8 Useful Facts About Uranus

Uranus as seen by the human eye (left) and with colored filters (right).
Uranus as seen by the human eye (left) and with colored filters (right).
NASA/JPL

The first planet to be discovered by telescope, Uranus is the nearest of the two "ice giants" in the solar system. Because we've not visited in over 30 years, much of the planet and its inner workings remain unknown. What scientists do know, however, suggests a mind-blowing world of diamond rain and mysterious moons. Here is what you need to know about Uranus.

1. ITS MOONS ARE NAMED AFTER CHARACTERS FROM LITERATURE.

Uranus is the seventh planet from the Sun, the fourth largest by size, and ranks seventh by density. (Saturn wins as least-dense.) It has 27 known moons, each named for characters from the works of William Shakespeare and Alexander Pope. It is about 1784 million miles from the Sun (we're 93 million miles away from the Sun, or 1 astronomical unit), and is four times wider than Earth. Planning a trip? Bring a jacket, as the effective temperature of its upper atmosphere is -357°F. One Uranian year last 84 Earth years, which seems pretty long, until you consider one Uranian day, which lasts 42 Earth years. Why?

2. IT ROTATES UNIQUELY.

Most planets, as they orbit the Sun, rotate upright, spinning like tops—some faster, some slower, but top-spinning all the same. Not Uranus! As it circles the Sun, its motion is more like a ball rolling along its orbit. This means that for each hemisphere of the planet to go from day to night, you need to complete half an orbit: 42 Earth years. (Note that this is not the length of a complete rotation, which takes about 17.25 hours.) While nobody knows for sure what caused this 98-degree tilt, the prevailing hypothesis involves a major planetary collision early in its history. And unlike Earth (but like Venus!), it rotates east to west.

3. SO ABOUT THAT NAME …

You might have noticed that every non-Earth planet in the solar system is named for a Roman deity. (Earth didn't make the cut because when it was named, nobody knew it was a planet. It was just … everything.) There is an exception to the Roman-god rule: Uranus. Moving outward from Earth, Mars is (sometimes) the son of Jupiter, and Jupiter is the son of Saturn. So who is Saturn's father? Good question! In Greek mythology, it is Ouranos, who has no precise equivalent in Roman mythology (Caelus is close), though his name was on occasion Latinized by poets as—you guessed it!—Uranus. So to keep things nice and tidy, Uranus it was when finally naming this newly discovered world. Little did astronomers realize how greatly they would disrupt science classrooms evermore.

Incidentally, it is not pronounced "your anus," but rather, "urine us" … which is hardly an improvement.

4. IT IS ONE OF ONLY TWO ICE GIANTS.

Uranus and Neptune comprise the solar system's ice giants. (Other classes of planets include the terrestrial planets, the gas giants, and the dwarf planets.) Ice giants are not giant chunks of ice in space. Rather, the name refers to their formation in the interstellar medium. Hydrogen and helium, which only exist as gases in interstellar space, formed planets like Jupiter and Saturn. Silicates and irons, meanwhile, formed places like Earth. In the interstellar medium, molecules like water, methane, and ammonia comprise an in-between state, able to exist as gases or ices depending on the local conditions. When those molecules were found by Voyager to have an extensive presence in Uranus and Neptune, scientists called them "ice giants."

5. IT'S A HOT MYSTERY.

Planets form hot. A small planet can cool off and radiate away heat over the age of the solar system. A large planet cannot. It hasn't cooled enough entirely on the inside after formation, and thus radiates heat. Jupiter, Saturn, and Neptune all give off significantly more heat than they receive from the Sun. Puzzlingly, Uranus is different.

"Uranus is the only giant planet that is not giving off significantly more heat than it is receiving from the Sun, and we don't know why that is," says Mark Hofstadter, a planetary scientist at NASA's Jet Propulsion Laboratory. He tells Mental Floss that Uranus and Neptune are thought to be similar in terms of where and how they formed.

So why is Uranus the only planet not giving off heat? "The big question is whether that heat is trapped on the inside, and so the interior is much hotter than we expect, right now," Hofstadter says. "Or did something happen in its history that let all the internal heat get released much more quickly than expected?"

The planet's extreme tilt might be related. If it were caused by an impact event, it is possible that the collision overturned the innards of the planet and helped it cool more rapidly. "The bottom line," says Hofstadter, "is that we don't know."

6. IT RAINS DIAMONDS BIGGER THAN GRIZZLY BEARS.

Although it's really cold in the Uranian upper atmosphere, it gets really hot, really fast as you reach deeper. Couple that with the tremendous pressure in the Uranian interior, and you get the conditions for literal diamond rain. And not just little rain diamondlets, either, but diamonds that are millions of carats each—bigger than your average grizzly bear. Note also that this heat means the ice giants contain relatively little ice. Surrounding a rocky core is what is thought to be a massive ocean—though one unlike you might find on Earth. Down there, the heat and pressure keep the ocean in an "in between" state that is highly reactive and ionic.

7. IT HAS A BAKER'S DOZEN OF BABY RINGS.

Unlike Saturn's preening hoops, the 13 rings of Uranus are dark and foreboding, likely comprised of ice and radiation-processed organic material. The rings are made more of chunks than of dust, and are probably very young indeed: something on the order of 600 million years old. (For comparison, the oldest known dinosaurs roamed the Earth 240 million years ago.)

8. WE'VE BEEN THERE BEFORE AND WILL BE BACK.

The only spacecraft to ever visit Uranus was NASA's Voyager 2 in 1986, which discovered 10 new moons and two new rings during its single pass from 50,000 miles up. Because of the sheer weirdness and wonder of the planet, scientists have been itching to return ever since. Some questions can only be answered with a new spacecraft mission. Key among them: What is the composition of the planet? What are the interactions of the solar wind with the magnetic field? (That's important for understanding various processes such as the heating of the upper atmosphere and the planet's energy deposition.) What are the geological details of its satellites, and the structure of the rings?

The Voyager spacecraft gave scientists a peek at the two ice giants, and now it's time to study them up close and in depth. Hofstadter compares the need for an ice-giants mission to what happened after the Voyagers visited Jupiter and Saturn. NASA launched Galileo to Jupiter in 1989 and Cassini to Saturn in 1997. (Cassini was recently sent on a suicide mission into Saturn.) Those missions arrived at their respective systems and proved transformative to the field of planetary science.

"Just as we had to get a closer look at Europa and Enceladus to realize that there are potentially habitable oceans there, the Uranus and Neptune systems can have similar things," says Hofstadter. "We'd like to go there and see them up close. We need to go into the system." 

This Innovative Cutting Board Takes the Mess Out of Meal Prep

There's no way any of these ingredients will end up on the floor.
There's no way any of these ingredients will end up on the floor.
TidyBoard, Kickstarter

Transferring food from the cutting board to the bowl—or scraps to the compost bin—can get a little messy, especially if you’re dealing with something that has a tendency to roll off the board, spill juice everywhere, or both (looking at you, cherry tomatoes).

The TidyBoard, available on Kickstarter, is a cutting board with attached containers that you can sweep your ingredients right into, taking the mess out of meal prep and saving you some counter space in the process. The board itself is 15 inches by 20 inches, and the container that fits in its empty slot is 14 inches long, 5.75 inches wide, and more than 4 inches deep. Two smaller containers fit inside the large one, making it easy to separate your ingredients.

Though the 4-pound board hangs off the edge of your counter, good old-fashioned physics will keep it from tipping off—as long as whatever you’re piling into the containers doesn’t exceed 9 pounds. It also comes with a second set of containers that work as strainers, so you can position the TidyBoard over the edge of your sink and drain excess water or juice from your ingredients as you go.

You can store food in the smaller containers, which have matching lids; and since they’re all made of BPA-free silicone, feel free to pop them in the microwave. (Remove the small stopper on top of the lid first for a built-in steaming hole.)

tidyboard storage containers
They also come in gray, if teal isn't your thing.
TidyBoard

Not only does the bamboo-made TidyBoard repel bacteria, it also won’t dull your knives or let strong odors seep into it. In short, it’s an opportunity to make cutting, cleaning, storing, and eating all easier, neater, and more efficient. Prices start at $79, and it’s expected to ship by October 2020—you can find out more details and order yours on Kickstarter.

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NASA Scientist Simulates What Sunsets Would Look Like on Venus, Mars, and Beyond

NASA's Curiosity rover captured this sunset at Mars' Gale crater in 2015.
NASA's Curiosity rover captured this sunset at Mars' Gale crater in 2015.
NASA/JPL-Caltech/MSSS/Texas A&M Univ.

Earth, Venus, and Mars all share the same sun, but due to factors like distance and atmospheric composition, it looks different from each planet. This is especially true during sunset, when sunlight travels through more of a planet's atmosphere. Now you don't have to imagine what an extraterrestrial sunset would look like: The video below, created by a NASA scientist, shows realistic simulations of different sunsets throughout the solar system.

Planetary scientist Geronimo Villanueva from NASA's Goddard Space Flight Center in Greenbelt, Maryland, came up with the idea while working on a computer modeling tool for potential Uranus missions. The model helps scientists study how sunlight interacts with the atmospheres of other planets. This data can tell us a lot about a planet's chemical makeup, and as Villanueva discovered when testing the tool, it can also show us what an otherworldly sunset looks like.

After modeling a Uranian sunset, Villanueva built simulations for sky colors on Earth, Venus, Mars, and Saturn's moon Titan. In the clip below, you can see the sky domes of the eight celestial bodies, plus a hazy version of Earth. As the sun moves from horizon to horizon, the colors of each circle start to change. On Mars, for example, the sky transitions from brown to grayish blue, because the fine Martian dust particles in the atmosphere are effective at scattering blue light from the sun when it's low in the sky.

Once you've watched this simulation, check out what an eclipse would look from the surface of our planetary neighbors.