Buzz
Rain, snow, sleet, and hail are some of the most common forms of precipitation. The type you're most familiar with, and how frequently it occurs, is influenced by the climate of the area you reside in. However, no matter the form, precipitation on Earth is composed of water.
Other planets and moons also experience unique forms of precipitation. Rainstorms and snowfalls on distant worlds are made up of elements vastly different from what we see on Earth. This gives rise to some remarkable phenomena, such as ruby rain and gasoline showers.
10. Rock Rain
First detected in February 2009, COROT-7b is an exoplanet that is nearly twice the size of Earth. While its density is comparable to our planet's, the environment on COROT-7b is far from hospitable. This exoplanet orbits roughly 2.5 million kilometers (1.5 million mi) from its star, a stark contrast to Mercury's closest approach of about 47 million kilometers (29 million mi) to the Sun.
Due to its close orbit to its star, COROT-7b is tidally locked, meaning one side always faces the sun. The sunlit side reaches scorching temperatures of around 2,327 degrees Celsius (4,220 °F), hot enough to melt and vaporize rock, which leads to its distinct type of precipitation.
COROT-7b’s surface is covered in vast oceans and lakes of molten lava. The vaporized rock rises into the atmosphere, where it cools and condenses into rock clouds. These clouds then rain down hot, tiny pebbles back into the lava oceans, continuing a cycle akin to the water cycle we experience on Earth.
9. Glass Rain
HD 189733b, an exoplanet discovered by the Hubble Space Telescope in 2005, is a blue giant that belongs to the 'hot Jupiter' category. Hot Jupiters are massive, gaseous planets that orbit their stars very closely, resulting in blistering surface temperatures. On HD 189733b, daytime temperatures soar up to 930 degrees Celsius (1,700 °F), while Jupiter’s average temperature is a frigid minus 148 degrees Celsius (–234 °F).
Located 63 light-years away from Earth, HD 189733b may appear blue from a distance, but that’s where the similarities to Earth end. Its vibrant hue is a result of the intense glass rain that blasts across the planet. With wind speeds reaching seven times the speed of sound, at 8,700 kilometers per hour (5,400 mph), the atmosphere of HD 189733b is filled with clouds containing silicate particles. When these clouds release the particles, the extreme heat melts the glass, and the fierce winds drive the rain sideways.
8. Dry Ice Snow
Mars experiences powerful snowstorms that take place during the late hours of the night.
Mars, our neighboring planet, is home to clouds made of water and ice that hang just 1 to 2 kilometers (0.6–1.2 mi) above its surface. It was once thought that precipitation from these clouds would take hours or even days to reach the Martian ground. However, data from the Mars Global Surveyor and Mars Reconnaissance Orbiter revealed that Martian snowfall can hit the surface in less than ten minutes.
When the Sun sets on Mars, the temperature drops dramatically, and fierce winds whip through the atmosphere, creating snowstorm conditions. These nighttime snowstorms, known as 'ice microbursts,' are similar to localized storms that occasionally occur on Earth.
Some snowstorms on Mars, particularly near its southern pole, are composed of dry ice. These storms form clouds made of frozen carbon dioxide. The snowflakes from these clouds fall in such dense amounts that they accumulate, adding to the carbon dioxide ice cap that covers Mars' south pole.
7. Gemstone Rain
HAT-P-7b is an exoplanet situated 1,000 light-years from Earth. The planet is 40 percent larger than Jupiter and orbits a star that is twice the size of our Sun. Being in close proximity to its massive star, HAT-P-7b is tidally locked. The side facing the star endures average temperatures of 2,586 degrees Celsius (4,687°F), while the dark side is significantly cooler. This stark temperature difference creates powerful winds that sweep around the planet.
Clouds form on the cooler, dark side of HAT-P-7b. These clouds are blown by fierce winds toward the sunlit side, but they don’t last long there, as they quickly vaporize in the intense heat.
The clouds on HAT-P-7b are striking. They contain corundum, the mineral responsible for creating sapphires and rubies on Earth. The corundum rain that falls from these clouds must be a magnificent sight, although astronomers still need to study the planet's atmosphere further to understand how corundum precipitation interacts with other compounds as it makes its way down to the surface.
6. Sunscreen Snow
Kepler-13Ab is an extraordinarily hot exoplanet situated 1,730 light-years away from Earth. This planet experiences titanium dioxide snow, a key ingredient in sunscreen. Ironically, the sunscreen snow only falls on the dark side of the planet.
Kepler-13Ab is another 'hot Jupiter,' orbiting its star closely and tidally locked. The temperature on its dayside reaches an astounding 2,760 degrees Celsius (5,000 °F), making it one of the hottest known exoplanets.
While most Hot Jupiters radiate heat, warming their upper atmospheres more than their lower ones, Kepler-13Ab stands out as the only hot Jupiter where the opposite occurs. This anomaly happens because the dayside of the planet lacks titanium oxide, the compound responsible for heat absorption and radiation in other hot Jupiters.
Scientists found that titanium oxide only appears on the dark side of Kepler-13Ab. It is thought that intense winds carried the compound from the dayside to the nightside, where it cooled, condensed into clouds, and eventually precipitated as titanium snow. This snow is drawn into the lower atmosphere by the planet's strong surface gravity.
5. Celestial Rain
Enceladus, the sixth-largest moon of Saturn, baffled scientists for 14 years. Water vapor was detected in Saturn’s upper atmosphere, but its origin was unknown. The mystery was solved in 2011, when the European Space Agency’s Herschel Space Observatory, the largest infrared space telescope ever launched, uncovered the source.
Geysers on Enceladus' southern pole regularly shoot out icy water, releasing around 250 kilograms (550 lb) of water into space every second. While much of it falls back to the moon's surface, some escapes into space, some strikes Saturn’s rings, and a small portion makes its way into the planet’s atmosphere.
Enceladus contributes three to five percent of its water into Saturn’s atmosphere, forming a continuous water vapor ring that the moon replenishes as it orbits the planet.
Enceladus is the only moon in the solar system that alters the chemistry of its parent planet. The water vapor it sends to Saturn’s atmosphere creates compounds containing oxygen, like carbon dioxide, which eventually sink deeper into Saturn, forming small clouds.
4. Acid Rain
It was once believed that metal snowed on Venus. The planet’s mountains seemed to be covered in a layer of frozen snow, which, given the intense heat on Venus, seemed impossible. A closer inspection of the mountain peaks revealed they were actually made of galena and bismuthinite, two types of metal. However, the metals don’t fall from the sky like snow. In Venus's valleys, these metals vaporize and form a mist that rises, eventually settling and condensing on the mountain tips, creating a metallic frost from a rising fog, not falling snow.
Venus, however, does experience a distinct type of precipitation. Sulfuric acid rainstorms occur regularly on the planet.
In Venus’s upper atmosphere, trace amounts of water combine with sulfur dioxide to produce sulfuric acid clouds. These clouds frequently erupt in intense storms, but the sulfuric acid rain evaporates before reaching the surface. Once the rain evaporates, it rises in the atmosphere, reforming sulfuric acid clouds and restarting the cycle.
3. Plasma Rain
Even the Sun experiences precipitation, but not the typical rain — rather, it is plasma rain.
NASA’s Interface Region Imaging Spectrograph, or IRIS, is a solar satellite tasked with observing the Sun’s behavior. Since 2013, IRIS has captured stunning images of solar flares, along with the resulting phenomena like post-flare loops or coronal rain.
A solar flare is a violent burst of radiation, releasing vast amounts of magnetic energy. This energy heats the Sun’s atmosphere, sending energized particles racing into space. These solar materials then rain back down onto the Sun’s surface as plasma, a gaseous substance composed of positively and negatively charged ions, all guided by intricate magnetic forces.
Curiously, as plasma rain nears the Sun’s surface, it cools rapidly. This is because the Sun’s outer atmosphere, known as the corona, is significantly hotter than its surface. Scientists are still unraveling the mystery behind this temperature discrepancy.
2. Diamond Rain
Neptune and Uranus may host the most extravagant rainfall in the universe. Their extraordinary precipitation takes place about 10,000 kilometers (6,200 mi) beneath their surfaces. There, diamonds cascade toward the planets' cores, forming icebergs of diamond that float upon seas of liquid carbon.
To replicate this effect on Earth, scientists substituted polystyrene for the methane compounds found on Neptune and Uranus. Using a tool called Matter in Extreme Conditions, they simulated the intense heat and pressure that causes carbon within these planets to transform into diamonds. Under temperatures approaching 4,727 degrees Celsius (8,540 °F) and pressures akin to those deep inside Neptune and Uranus, minute diamonds were created.
The diamonds produced in the laboratory were only a few nanometers in size because the experimental conditions lasted only briefly. However, the diamonds that form and accumulate near the cores of Neptune and Uranus, where such extreme conditions persist, would be far larger—up to millions of carats in weight.
1. Methane Monsoons
Titan, the largest moon of Saturn, is the only other place in our solar system aside from Earth where liquid falls onto a solid surface. However, on Titan, the rain is made of liquid methane.
Titan’s surface is dotted with lakes and seas composed of natural gas. Hydrocarbon clouds deliver rain that pours massive amounts of methane in a short span. The intensity of Titan's rainfall varies, causing some areas to erode and form new lakes, while others gain only a few dunes.
Titan experiences intense monsoon storms, but they only occur once every Titan year. With a Titan year equivalent to 30 Earth years, this means long dry periods. When Titan does experience rain, the amount of liquid methane that falls is comparable to the rainfall that Hurricane Harvey brought to Houston in 2017.
