Space

10 places to find snow beyond Earth

Snow: Pink horizon over snowcapped mountains and blue water, man standing with arms spread at peak.
Harry Haldeman in Lake Wanaka, New Zealand, shared this photo with EarthSky that he took on March 12, 2016. Harry wrote: “After a 2-hour hike to the top of Roys Peak with a group of 10 friends and colleagues, 2 of us split of to watch the sun come down over the peaks. Lucky to get such beautiful contrasts of colors.” Thank you, Harry! On Earth, we see snow everywhere from the poles to mountaintops. Where can we find snow and ice in the rest of the solar system?

On Earth, you can find snow at the poles and on tops of mountains in tropical climates and covering the ground over months-long stretches of winter. But did you know there are many other places in the solar system that are also home to snow? Here are just 10 locations beyond Earth where you might find snow or ice of various kinds.

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#1 – Earth’s moon

At one time we thought the moon was bone dry. But NASA’s Lunar Reconnaissance Orbiter (LRO) has shown us otherwise. It has spotted small patches of ice that could make up 5% to 10% of material in the walls of Shackleton crater. LRO is one of several spacecraft that have detected water ice in shadowy craters near the north and south poles of the moon.

Two spheres represent the south pole (left) and north pole (right) of the moon. There are indications of water ice marked in green.
Scientists directly observed definitive evidence of water ice on the moon’s surface in 2018. The image shows the distribution of surface ice at the moon’s south pole (left) and north pole (right), detected by NASA’s Moon Mineralogy Mapper instrument. Blue represents the ice locations, and the gray scale corresponds to surface temperature (darker representing colder areas and lighter shades indicating warmer zones). The ice is concentrated at the darkest and coldest locations, in the shadows of craters. Image via NASA.

#2 – Mars

The north and south poles of Mars have ice caps that grow and shrink with the seasons. These ice caps are made mainly of water ice, which is the same kind of ice you’d find on Earth. However, the snow that falls there is made of carbon dioxide. On Earth, frozen carbon dioxide is what we call dry ice. Carbon dioxide is in the Martian atmosphere where it can make clouds and freeze and fall to the surface as snow. NASA’s Mars Reconnaissance Orbiter has seen many instances of snowfall on Mars.

Undulating sand dunes on Mars with deposits of bluish white snow and ice.
Rocks and sand dunes cover Mars’ surface, and also, sometimes, snow and ice. In the winter at high latitudes, the terrain is covered by carbon-dioxide ice, or dry ice. In spring, the seasonal ice changes to water vapor, exposing the features below. On the floor of the craters, ice forms an uninterrupted layer. But on the dunes you can see dark streaks, where surface material is on top of the ice. Image via NASA/ JPL-Caltech/ University of Arizona.

#3 – Io

Of all Jupiter’s moons, you may not think of its volcanic moon, Io, as a place for snow. But the moon has “snowflakes” made of sulfur. In 2001, NASA’s Galileo spacecraft detected these sulfur snowflakes just above Io’s south pole. The sulfur shoots into space from a volcano on Io’s surface. In space, the sulfur quickly freezes to form snowflakes that fall back down to the surface.

Yellowish world with plume ejecting from limb.
One of the most surprising discoveries by Voyager 1 was the violent volcanoes of Jupiter’s moon Io. Equally surprising is that this volcanic world is home to sulfur snow. Image via NASA/ JPL-Caltech.

#4 – Europa

Jupiter’s moon Europa is an icy world with a liquid ocean below the frozen surface. NASA is planning a mission – Europa Clipper – to further explore Europa with a launch slated for 2024. Europa’s icy, cracked crust and subsurface ocean may be one of the best places in the solar system for life to have taken hold.

Half a lit white sphere streaked with brown lines.
Jupiter’s moon Europa has a water-ice surface crisscrossed by fractures. Image via NASA/ JPL-Caltech.

#5 – Enceladus

Saturn’s moon Enceladus has geysers that shoot water vapor out into space. It then freezes and falls back to the surface as snow. Some of the ice also escapes Enceladus to become part of Saturn’s rings. The water vapor comes from a heated ocean that lies beneath the moon’s icy surface. All this ice and snow make Enceladus one of the brightest objects in our solar system.

Beams of light projecting upward off the surface of a round sphere.
Cassini captured this image of jets issuing from Saturn’s moon Enceladus. Image via NASA/ JPL-Caltech/ Space Science Institute.

#6 – Mimas

Saturn’s small moon Mimas, despite its Death Star look, is actually just a ball of almost pure water ice about 123 miles (198 km) across.

Gray sphere pockmarked plus a huge crater.
NASA’s Cassini spacecraft took this image of Mimas on February 13, 2010. You can see how the astounding Herschel Crater dominates Mimas. Image via NASA/ JPL-Caltech/ Space Science Institute.

#7 – Triton

Neptune’s largest moon is Triton. It has one of the coldest surfaces in our solar system. Triton’s atmosphere consists mainly of nitrogen, which freezes onto its surface. Triton also has geysers like Enceladus, though they are smaller and made of nitrogen rather than water.

Mottled beige and blue sphere closeup.
In 1989, Voyager 2 took this global color mosaic of Triton during its flyby of the Neptunian system. Scientists think the dark streaks overlying these pink ices are icy and perhaps carbonaceous dust deposited from huge geyser-like plumes, some of which were found to be active during the Voyager 2 flyby. Image via NASA/ JPL-Caltech.

#8 – Pluto

Far out in our solar system lies the dwarf planet Pluto. In 2016, scientists with the New Horizons mission discovered a mountain chain on Pluto where the mountains were capped with methane snow and ice.

Mountain terrain with bright patches seen from above, in two large rectangles.
Snowcapped mountains on Pluto look a lot like snowcapped mountains on Earth. At left is the Cthulhu Regio on Pluto. On the right is the Alps on Earth. Image via NASA.

#9 – Mercury

Surprise! We went all the way to the fringes of the solar system only to come back close to the sun. NASA’s MESSENGER spacecraft provided compelling support for the long-held hypothesis that Mercury harbors abundant water ice and other frozen volatile materials in its permanently shadowed polar craters.

Cratered grey circle with possible water ice marked in yellow.
The MESSENGER mission to Mercury, which orbited the planet between 2011 and 2015, detected what appears to be water ice in craters around Mercury’s poles. Image via ESA.

#10 – Kepler-13Ab

Snow and ice probably exist outside our solar system, too. One bizarre example of that is Kepler-13Ab. This hot, giant planet is 1,730 light-years from Earth. It’s nine times more massive than Jupiter, and it orbits very close to its star. The Hubble Space Telescope detected evidence of titanium oxide – the mineral used in sunscreen – in this planet’s upper atmosphere. On the cooler side of Kepler-13Ab that faces away from its host star, the planet’s strong gravity might cause the titanium oxide to fall down as “snow.”

From left to right: orange big sphere, medium bright sphere, tiny red sphere and small bright sphere.
Artist’s concept of the multiple star system that includes the exoplanet Kepler-13Ab. The seething-hot planet circles close to its host star, Kepler-13A. In the background is the star’s binary companion, Kepler-13B, and the third member of the multiple-star system, the orange dwarf star Kepler-13C. Image via NASA/ ESA/ G. Bacon (STScI).

Bottom line: On Earth, you can find snow at the poles and on tops of mountains in tropical climates and covering the ground over long stretches of winter. There are plenty of other places in the solar system, and probably the universe, that are home to snow as well.

Posted 
January 4, 2018
 in 
Space

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