What the Weather Is Like on Other Moons and Planets

On Earth, we get snow, rain, fog, hail, and sleet, and all of them are basically the same thing: water. For a true change of weather, you need to go to other worlds. Here's a tour of what to expect on a trip through our solar system.

Mars: Dry Ice Snow

Scientists have known for years that the polar caps of Mars are made of a combination of water ice and dry ice (or frozen carbon dioxide—the same stuff that makes fog when you dump it into a pot of water). But how does it get there? The ice caps grow and recede with the seasons (in the Hubble images above, the carbon dioxide is receding with the onset of spring), so either the carbon dioxide is freezing directly out of the atmosphere, or it's snowing. Scientists working with data from Mars Reconnaissance Orbiter recently solved the puzzle: MRO detected clouds of carbon dioxide crystals, and clear evidence of snow falling out of them. The snow would not fall as flakes, but as tiny cuboctohedrons (which have eight triangular faces and six square faces). On the surface, Mars snow probably looks like granulated sugar.

Venus: Sulfuric Acid Rain

Once thought to be our sister planet, Venus is, in actuality, a hellhole. The surface is over 462 degrees C (864 degrees F)—easily hot enough to melt lead—and the atmospheric pressure is about 92 times the pressure on Earth at sea level. It's also bone dry (water is baked out of the soil). But high up above the slowly rotating surface, where the winds whip violently, Venus is enshrouded by clouds of sulfuric acid (shown here in ultraviolet light from the Hubble Telescope). When it rains, the acid falls down to about 25 km before evaporating—at these temperatures, even sulfuric acid can't stay liquid. The vapor rises back up to recondense as clouds, giving Venus a liquid cycle confined entirely to the upper atmosphere.

Io: Sulfur Dioxide Snow

Venus isn't the only hellhole in the solar system. Jupiter's moon Io would fit the bill pretty well, too. It's riddled with active volcanoes, covered in brimstone, and hiding a subsurface ocean of lava. And it snows the sort of snow you might get when Hell freezes over, because it too is made of brimstone: sulfur, and, more specifically, sulfur dioxide, which were detected when the Galileo orbiter flew through the volcanic plumes on its kamikaze mission in September 2003. Molten sulfur, heated to the boiling point below the surface of Io by torturous tidal flexing, sprays out of the volcanoes like a geyser would spray water on Earth. In the cold, airless void of space, the sulfur dioxide quickly crystalizes into tiny flakes; most of it falls back to the surface as a fluffy yellow snow. Galileo's sensors indicated that the particles were very small, perhaps 15-20 molecules apiece, so the snow would look extremely fine on the surface.  In the photo above, the broad white semi circle of material is sulfur dioxide snow from a plume called Amirani.

Titan: Methane Rain

Titan is Saturn's largest moon, and the pictures revealed by Cassini and the Huygens lander show a world that looks surprisingly Earthlike, with riverbeds, lakes, and clouds. (The radar image above shows the shores of Kraken Mare, the largest known lake on Titan, with rivers flowing into it.) But this is deceptive. Titan is much colder: What looks like rock is water ice, and what looks like water is natural gas. A methane cycle (much like the water cycle on Earth) exists on Titan, driving seasonal rains that follow patterns (much like the ones tropical monsoons follow on Earth). When the season is right, the rain falls, filling vast but shallow basins bigger than our Great Lakes. As the seasons change, the lakes slowly evaporate. The vapor makes its way up into the atmosphere and condenses into clouds; the clouds drift to the other hemisphere as the weather shifts, and when the rain falls, it starts the next loop of the cycle.

Enceladus: Water and Ammonia Snow

Enceladus is one of the most active moons of Saturn. The south polar region especially is riddled with geysers that shoot water and ammonia hundreds of miles into space. Most of that leaves Enceladus altogether, forming Saturn's E ring. The rest falls back down, forming deep, powdery snow that would put the best "white smoke" of the Rockies to shame. But the snow falls very slowly. By mapping the snowdrifts, scientists have found that although the snow barely accumulates over the course of a year, the snow has been falling on some spots for tens of millions of years. Because of this, the snowpack is over 100 meters deep. And it's all light, fluffy snow; an unwary skier might disappear into the powder if he hit a particularly deep patch. This photo above shows Cairo Sulcus, a grooved feature in Encealdus' active south, its sharp edges softened by millenia of gentle snowfall.

Triton: Nitrogen and Methane Snow

Titan is cold enough to liquify methane, but Neptune's moon Triton is colder still. Voyager 2 discovered that Triton's surface is suspiciously new, and it's not just from volcanic resurfacing; the southern polar region also appears to be covered partially in a light, fluffy material that could only be snow. But while our snow is white and Io's snow is yellow, Triton's snow is pink. It's made of a mixture of nitrogen and methane. Like Io and Enceladus, the snow comes from geysers that blast liquid high up into space, where it freezes into fine particles that fall down as snow onto a terrain pockmarked by nitrogen/methane permafrost. Because of its color and the curious texture of the southern polar region, scientists call it "cantaloupe terrain."

Pluto: Nitrogen, Methane, and Carbon Monoxide Snow

Pluto has an awful lot in common with Triton, and apparently that includes snow. Although Pluto has never been seen close-up, careful observations with the Hubble Space Telescope suggest that it experiences snows of nitrogen, methane, and possibly carbon monoxide. Like Triton, this makes its surface very pinkish. Depending on the process that desposits it (geysers or frost or "diamond dust" snowfall, where the stuff just freezes straight out of the air and falls), this could be a fine powder or big, spiky piles of frost. We'll know more when NASA's New Horizons spacecraft visits; right now, it's about halfway there.

Jupiter: Liquid Helium Rain

The environments on gas giant planets are extreme in many ways; one is that there is a depth within them at which the atmospheric pressure is so great that exotic forms of matter appear, such as metallic helium and hydrogen. If the models are correct, above Jupiter's rocky core lies a deep ocean of liquid metallic hydrogen. Helium is a little harder to compress into a metallic form, so it doesn't mix with this ocean. It is heavier than hydrogen, though; scientists believe it falls through the metallic hydrogen ocean like droplets falling through the atmosphere, until it gets deep enough to become metallic.

Uranus and Neptune: Diamond Rain

Uranus and Neptune aren't really Jovian worlds; they're much colder than Jupiter or Saturn, and contain high fractions of water, leading some to call them ice giants. Another thing they contain is methane—lots of it, pressurized into a liquid state inside the giant planets. Methane is a hydrocarbon; under the right conditions (and models predict such conditions on Uranus and Neptune), the carbon within it can crystallize out as tiny diamonds. On Earth, "diamond dust" means superfine particles of ice suspended in the atmosphere on very cold days, but the phrase might be more literally true on Uranus and Neptune. The diamonds aren't accessible; they continually rain down towards the interior of the planets to be lost forever in a vast diamond ocean.  Fans of Arthur C. Clarke may recognize this idea as part of the inspiration for "2061."

Bonus — The Sun: Plasma Rain

The Sun represents 99 percent of the mass in our solar system, so fittingly, it has what may be the most extreme precipitation in the solar system: plasma rain. Unlike the others on this list, you can actually see it from Earth. Huge loops of plasma are lifted up into space above the photosphere (what is generally considered the "surface" of the Sun) and suspended by magnetism, until finally something snaps and material is hurled violently into space in a coronal mass ejection. Not all of the material escapes, however; a lot of it falls back down as coronal rain. The video above, from June 7, 2011, was a particularly big and dramatic coronal mass ejection; look for the bright flashes as material impacts the photosphere.

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These Sparrows Have Been Singing the Same Songs for 1500 Years
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Swamp sparrows are creatures of habit—so much so that they’ve been chirping out the same few tunes for more than 1500 years, Science magazine reports.

These findings, published in the journal Nature Communications, resulted from an analysis of the songs of 615 adult male swamp sparrows found in six different areas of the northeastern U.S. Researchers learned that young swamp sparrows pick up these songs from the adults around them and are able to mimic the notes with astounding accuracy.

Here’s what one of their songs sounds like:

“We were able to show that swamp sparrows very rarely make mistakes when they learn their songs, and they don't just learn songs at random; they pick up commoner songs rather than rarer songs,” Robert Lachlan, a biologist at London’s Queen Mary University and the study’s lead author, tells National Geographic.

Put differently, the birds don’t mimic every song their elders crank out. Instead, they memorize the ones they hear most often, and scientists say this form of “conformist bias” was previously thought to be a uniquely human behavior.

Using acoustic analysis software, researchers broke down each individual note of the sparrows’ songs—160 different syllables in total—and discovered that only 2 percent of sparrows deviated from the norm. They then used a statistical method to determine how the songs would have evolved over time. With recordings from 2009 and the 1970s, they were able to estimate that the oldest swamp sparrow songs date back 1537 years on average.

The swamp sparrow’s dedication to accuracy sets the species apart from other songbirds, according to researchers. “Among songbirds, it is clear that some species of birds learn precisely, such as swamp sparrows, while others rarely learn all parts of a demonstrator’s song precisely,” they write.

According to the Audubon Guide to North American Birds, swamp sparrows are similar to other sparrows, like the Lincoln’s sparrow, song sparrow, and chipping sparrow. They’re frequently found in marshes throughout the Northeast and Midwest, as well as much of Canada. They’re known for their piercing call notes and may respond to birders who make loud squeaking sounds in their habitat.

[h/t Science magazine]

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10 Scientific Benefits of Being a Dog Owner
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The bickering between cat people and dog people is ongoing and vicious, but in the end, we're all better off for loving a pet. But if anyone tries to poo-poo your pooch, know that there are some scientific reasons that they're man's best friend.

1. YOU GET SICK LESS OFTEN.

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If cleaning commercials are to be believed, humanity is in the midst of a war against germs—and we shouldn't stop until every single one is dead. In reality, the amount of disinfecting we do is making us sicker; since our bodies are exposed to a less diverse mix of germs, our entire microbiome is messed up. Fortunately, dogs are covered in germs! Having a dog in the house means more diverse bacteria enters the home and gets inside the occupants (one study found "dog-related biodiversity" is especially high on pillowcases). In turn, people with dogs seem to get ill less frequently and less severely than people—especially children—with cats or no pets.

2. YOU'RE MORE RESISTANT TO ALLERGIES.

Child and mother playing with a dog on a bed.
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While dog dander can be a trigger for people with allergies, growing up in a house with a dog makes children less likely to develop allergies over the course of their lives. And the benefits can start during gestation; a 2017 study published in the journal Microbiome found that a bacterial exchange happened between women who lived with pets (largely dogs) during pregnancy and their children, regardless of type of birth or whether the child was breastfed, and even if the pet was not in the home after the birth of the child. Those children tested had two bacteria, Ruminococcus and Oscillospira, that reduce the risk of common allergies, asthma, and obesity, and they were less likely to develop eczema.

3. YOU'LL HAVE BETTER HEART HEALTH.

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Everything about owning a dog seems to lend itself to better heart health. Just the act of petting a dog lowers heart rate and blood pressure. A 2017 Chinese study found a link between dog ownership and reduced risk of coronary artery disease, while other studies show pet owners have slightly lower cholesterol and are more likely to survive a heart attack.

4. YOU GET MORE EXERCISE.

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While other pets have positive effects on your health as well, dogs have the added benefit of needing to be walked and played with numerous times a day. This means that many dog owners are getting 30 minutes of exercise a day, lowering their risk of cardiovascular disease.

5. YOU'LL BE HAPPIER.

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Dog owners are less likely to suffer from depression than non-pet owners. Even for those people who are clinically depressed, having a pet to take care of can help them out of a depressive episode. Since taking care of a dog requires a routine and forces you to stay at least a little active, dog owners are more likely to interact with others and have an increased sense of well-being while tending to their pet. The interaction with and love received from a dog can also help people stay positive. Even the mere act of looking at your pet increases the amount of oxytocin, the "feel good" chemical, in the brain.

6. YOU HAVE A MORE ACTIVE SOCIAL LIFE.

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Not only does dog ownership indirectly tell others that you're trustworthy, your trusty companion can help facilitate friendships and social networks. A 2015 study published in PLOS One found that dogs can be both the catalyst for sparking new relationships and also the means for keeping social networks thriving. One study even showed that those with dogs also had closer and more supportive relationships with the people in their lives.

7. YOUR DOG MIGHT BE A CANCER DETECTOR.

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Your dog could save your life one day: It seems that our canine friends have the ability to smell cancer in the human body. Stories abound of owners whose dogs kept sniffing or licking a mole or lump on their body so they got it checked out, discovering it was cancerous. The anecdotal evidence has been backed up by scientific studies, and some dogs are now trained to detect cancer.

8. YOU'LL BE LESS STRESSED AT WORK.

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The benefits of bringing a dog to work are so increasingly obvious that more companies are catching on. Studies show that people who interact with a pet while working have lower stress levels throughout the day, while people who do not bring a pet see their stress levels increase over time. Dogs in the office also lead to people taking more breaks, to play with or walk the dog, which makes them more energized when they return to work. This, in turn, has been shown to lead to much greater productivity and job satisfaction.

9. YOU CAN FIND OUT MORE ABOUT YOUR PERSONALITY.

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The kind of dog you have says a lot about your personality. A study in England found a very clear correlation between people's personalities and what type of dogs they owned; for example, people who owned toy dogs tended to be more intelligent, while owners of utility dogs like Dalmatians and bulldogs were the most conscientious. Other studies have found that dog owners in general are more outgoing and friendly than cat owners.

10. YOUR KIDS WILL BE MORE EMPATHETIC.

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Though one 2003 study found that there is no link between pet ownership and empathy in a group of children, a 2017 study of 1000 7-12 year olds found that pet attachment of any kind encouraged compassion and positive attitudes toward animals, which promoted better well-being for both the child and the pet. Children with dogs scored the highest for pet attachment, and the study notes that "dogs may help children to regulate their emotions because they can trigger and respond to a child's attachment related behavior." And, of course, only one pet will happily play fetch with a toddler.

A version of this story originally ran in 2015.

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