It's Cold Out There

Hoping for a snow day? Well, if you lived on Jupiter's icy moon Europa you might have to call it an "ice day," and it wouldn't come seasonally either, it would be every day. And a "day" on Europa is quite long: about the equivalent of three and a half 24-hour long Earth days -- that's about 60 hours. It is also -260 degrees Fahrenheit there (and even colder at the poles: -370 degrees Fahrenheit). (I don't think that you would like that.)

No, you would not, and you could not live on a place like Europa, but yet this ice on Europa (and on other places) intrigues us -- we want to learn more about it. Why are we so interested in ice? Ice hints at the possibility for life.

Ice is one of the three phases (solid, liquid, gas) of an element or compound, such as H₂O (a.k.a. water). Water freezes and becomes a solid at 32 degrees Fahrenheit. Now, water is one of the building blocks of life and is essential to life here on Earth. Cool fact: Did you know that 75% of the Earth's freshwater is ice? That is a large percentage of all the water available for us to drink -- and survive. If we have found ice elsewhere, this hints at the possibility for past life on the other planets, and the moons of the planets.

Ice or evidence for ice -- yes, even water ice -- is found on many of the planets, the Moon and the moons of the planets. However, ice can be made out of many elements, such as nitrogen and carbon dioxide. The ice giants' (Uranus and Neptune) compositions are made up of different amounts of different kinds of ices. Saturn's rings are made up of 90% water ice. Mars has water ice and carbon dioxide ice located mostly near its poles. The Moon's ices are found in craters in the lunar south pole. Even close to the sun, and hot, Mercury has the possibility for ice in its perpetually shadowed polar regions.

One hypothesis as to how the Earth and the other planets and moons obtained ice and water on their surfaces (and beneath) is from incoming comets. Comets are considered to be "dirty snowballs" being made up of ice and dust. During the period of heavy bombardment in our solar system's history, a comet (or comets) could have impacted our Earth and the other bodies in our solar system and deposited its ices.

The solar system is a cold place, and yet ice gives us something to be excited about: Ice on the other planetary bodies gives us hope that one day we could discover some form of life out there. Ice is nice -- take a look below and see for yourself. (10 images total)

Wilkins Ice Bridge: This picture shows the Wilkins Ice Shelf, on the western side of the Antarctic Peninsula. An ice shelf is a thick slab of ice that is attached to a coastline. We see here varying sizes of ice fragments mixed with ice mélange. A crack in the east reveals dark ocean water below. Image Credit: NASA

Water Ice on Mars: ESA's Mars Express obtained this perspective view of an unnamed impact crater located on Vastitas Borealis, a broad plain that covers much of Mars's far northern latitudes. The coordinates are about 70.5 degrees north and 103 degrees east. The crater is 35 km wide and has a maximum depth of approximately 2 km beneath the crater rim. The circular patch of bright material located at the center of the crater is residual water ice. Image Credit: ESA/DLR/FU Berlin (G. Neukum)

Highlighting Plumes: At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus in this dramatically illuminated image. Light reflected off Saturn is illuminating the surface of the moon while the sun, almost directly behind Enceladus, is backlighting the plumes. Image Credit: NASA/JPL/Space Science Institute

Freckled Europa: Reddish spots and shallow pits pepper the ridged surface of Jupiter's moon, Europa, in this view combining images and data taken by NASA's Galileo spacecraft during two different orbits around Jupiter. The dark spots are called "lenticulae," the Latin term for freckles. Their similar sizes and spacing suggest that Europa's icy shell may be churning away like a lava lamp, with warmer ice moving upward from the bottom of the ice shell while colder ice near the surface sinks downward. Other evidence has shown that Europa likely has a deep melted ocean under its icy shell. Ruddy ice erupting onto the surface to form the lenticulae may hold clues to the composition of the ocean and to whether it could support life. Image Credit: NASA/JPL/University of Arizona/University of Colorado

Comet Halley: Comets consist mostly of ice coated with dark organic material. Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system. In this image by Giotto from 1986 we see comet Halley's nucleus. A comet's nucleus contains icy chunks and frozen gases with bits of embedded rock and dust. Image Credit: Halley Multicolor Camera Team, Giotto Project, ESA

Icy Triton: This global color mosaic of Triton was taken in 1989 by Voyager 2 during its flyby of the Neptune system. Triton is the coldest known planetary body in the solar system. Triton is extremely cold -- temperatures on its surface are about -391 degrees Fahrenheit (-235 degrees Celsius). Triton is so cold that most of Triton's nitrogen is condensed as frost, making it the only satellite in the solar system known to have a surface made mainly of nitrogen ice. Image Credit: NASA/JPL/USGS

Ring Close-up: This Cassini image shows a close-up view of a density wave in Saturn's A ring. The view shows the dark, or unlit, side of the rings. Saturn's rings are made primarily of water ice. Since pure water ice is white, it is believed that different colors in the rings reflect different amounts of contamination by other materials such as rock or carbon compounds. There is also more ice toward the outer part of the rings -- and the A ring is the outermost main ring. Image Credit: NASA/JPL/Space Science Institute

Cool Summer: This image shows a view of the north polar region of Mars from orbit. The ice-rich polar cap (quasi-circular white area at center) is about 1,000 km across. It is bisected by a large canyon, Chasma Boreale, on the right side. Dark, spiral-shaped bands are troughs. Chasma Boreale is about the length of the Grand Canyon in the U.S. and up to 2-km deep. Image Credit: NASA/Caltech/JPL/E. DeJong/J. Craig/M. Stetson

Icy Mars: This high resolution photo of the surface of Mars was taken by Viking Lander 2 at its Utopia Planitia landing site in 1979. It shows a thin coating of water ice on the rocks and soil. Image Credit: NASA

Meteorite Hunters: If we didn't have so much ice on the Earth we might not as easily find the meteorites that have been deposited here. It is in Antarctica were we have found many meteorites and the finding and study of theses meteorites further the study of our solar system. Meteorites collected by the ANSMET (Antarctic Search for Meteorites) team in Antarctica are packed in dry ice to mimic conditions in the field and shipped to the Antarctic Meteorite Laboratory at NASA's Johnson Space Center in Houston, Texas. Image Credit: NASA Johnson Space Center and Lunar and Planetary Institute

More Information:

• Year of the Solar System's April 2012 Topic: Ice!

Learn more about snow on Earth:

• Snowflake Background Science
• Explanation of Basic Snowflake Forms
• Our World Video on Snowflakes