There's no lack of ice in our solar system.
Frozen water can be found almost everywhere: the poles of Mercury, Earth, the moon and Mars; the rings and
icy satellites of the outer planets; and in comets that come whizzing past.
Winter in our Solar system is not as we know it on our planet.
It can be dark and cold, but it’s nothing compared with the
minus 280 degrees Fahrenheit temperatures on Mercury, the 21-year-long winter on Uranus, or the methane snow on Saturn's moon Titan.
The reason for the seasons on Earth is primarily the tilt of the planet's axis.
The Earth's stable axial tilt of about 23.4 degrees means
that it's predictably warm in the summer and cold in the winter.
Earth's tilt varies very little - by plus or minus one degree over a 41,000 year period (!)
and it keeps our climate relatively constant over long periods, allowing liquid water to flow and complex life to develop.
But without the stabilizing gravitational tugs from our large moon, our axialt tilt could vary much more dramatically.
So - were it not for our moon, there might not be winter as we know it, or summer, or oceans, or possibly even life!
Other places in our solar system have totally different weather conditions.
Europa, one of the four largest moons of
Jupiter is a little smaller than Earth's Moon. But it's covered in ice—smooth ice! It's gravity is only about 1/8th of Earth's,
so imagine the height you could get on a triple axel! Unfortunately, with Europa temperatures around -328° F, you would be frozen hard as a rock in a nanosecond!
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.
Credits: NASA/JPL/University of Arizona/University of Colorado
Mercury – Shadowed Snowballs
As the closest planet to the Sun, Mercury must be very hot, right? It is!
The average temperature is well over 300 degrees Fahrenheit (about 149 degrees Celsius) and noontime highs can top 800 F (427 C).
So how can there possibly be ice on Mercury?
The planet has very little tilt, so in Mercury's polar regions, the sun only appears low on the horizon, never high overhead.
This means that the floors of deep craters near the poles can be constantly in the dark.
These permanently shadowed cold traps may never get warmer than minus 280 degrees Fahrenheit (minus 173 degrees Celsius) -- yes, that's minus! --
cold enough for ice to stick around for billions of years.
Mercury - cold enough for ice to stick around for billions of years.
This shadowy image snapped by NASA's Messenger spacecraft is one of the most northern images taken of Mercury by the spacecraft.
Because the sun is always very low on the horizon at these high altitudes, much of Mercury's northern terrain is cast in shadow at a given time.
This image was acquired as part of MDIS's high-resolution surface morphology base map. The surface morphology base map will cover
more than 90% of Mercury's surface with an average resolution of 250 meters/pixel (0.16 miles/pixel or 820 feet/pixel).
Images acquired for the surface morphology base map typically have off-vertical Sun angles (i.e., high incidence angles)
and visible shadows so as to reveal clearly the topographic form of geologic features.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments
and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet.
These images are from MESSENGER, a NASA Discovery mission to conduct the first orbital study of the innermost planet,
Mercury. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Mars – The Sky Is Falling
Martian winter - Udzha Crater
The image was taken by the Thermal Emission Imaging System instrument on NASA's Mars Odyssey orbiter and posted in a special
December 2010 set marking the occasion of Odyssey becoming the longest-working Mars spacecraft in history. The pictured location on
Mars is 81.8 degrees north latitude, 77.2 degrees east longitude.
The northern and southern polar ice caps of Mars grow during their respective winters as carbon dioxide snow and frost condenses out of the Martian atmosphere.
Carbon dioxide makes up most of Mars' atmosphere - 95 percent! In the winter, 25 percent of that carbon dioxide precipitates out of the atmosphere as snow onto the
seasonal ice cap.
So the Martian sky is literally falling!
Although it is 28 miles (45 kilometers) wide, countless layers of ice and dust have all but buried Udzha Crater.
Udzha lies near the edge of Mars' northern polar cap, and only the topmost edges of its crater rim rise above the polar deposits to hint at its circular shape.
Saturn’s moon Tethys - Solar System’s Frozen Treat
Saturn's fifth largest moon, Tethys, is perhaps the largest chunk of ice (about 659 miles, or 1,060 kilometers, in diameter) with the least amount of rock
(about 3 percent). Now all you need is a planet flowing with flavored syrup, and it's snow cone time!
The Tethyan average temperature is -305 degrees Fahrenheit (-187 degrees Celsius).
Tethys as captured by the Cassini spacecraft's narrow-angle camera at a distance of approximately 32,300 km/20,000 mi.
Credits: Nasa/JPL/Space Science Institute)
Tethys (660 miles, or 1,062 kilometers across) appears just below the rings near the center of the image.
This view looks toward the northern, sunlit side of the rings from less than one degree above the ring plane.
The image was taken with the Cassini spacecraft wide-angle camera on Dec. 7, 2011 using a spectral filter sensitive to
wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.1 million miles
(1.8 million kilometers) from Tethys. Image scale is 66 miles (107 kilometers) per pixel on Tethys.
Credit: NASA/JPL-Caltech/Space Science Institute
Saturn’s Moon Titan – Titanic Snowfall
If the rains on Titan's plains are mainly made of methane, what about elsewhere? Methane snow, of course!
Saturn's moon Titan is the only place other than Earth known to have liquid flowing on its surface.
The difference is that while Earth's surface liquid is water, Titan's is probably liquid methane.
Scientists believe that methane, the primary component of natural gas here on Earth, flows freely as liquid on
Titan's surface and probably also precipitates out as snow on Titan's mountain tops.
It's worth noting that to "freeze" into a liquid and rain out of the clouds on Titan, the methane must be colder than -296.5° F (-182.5° C) !
Liquid Lakes on Saturn's Titan
Why would some regions on Titan reflect very little radar?
The leading explanation is that these regions are lakes, possibly composed of liquid methane.
The above image is a false-color synthetic radar map of a northern region of Titan taken during a
flyby of the cloudy moon by the robotic Cassini spacecraft last July. On this map, which spans about
150 kilometers across, dark regions reflect relatively little of the broadcast radar signal. Images like
this show Titan to be only the second body in the Solar System to possess liquids on the surface. Future
observations from Cassini during Titan flybys will further test the methane lake hypothesis, as comparative
wind effects on the regions are studied. Credit: Cassini Radar Mapper, JPL, ESA, NASA
Uranus – Will Winter Ever End?
If you think winter nights are long in the Arctic, where the sun doesn't rise for several months, imagine how you'd feel if you lived
on the seventh planet from our sun: Uranus.
Compared with other planets, Uranus is laying on its side, probably knocked over by a giant impact early in our solar system's history.
This large tilt, by 82° causes 20-year-long seasons and unusual weather, although one thing that is for certain is that it is always cold.
For nearly a quarter of the Uranian year (equal to 84 Earth years), the Sun shines directly over each pole, leaving the other half of
the planet plunged into a long, dark winter. The Uranian 'Arctic' is in complete darkness for almost the entire time!
Uranus - four times Earth's size and a mass fifteen times greater.
This view of Uranus was taken by NASA's Voyager 2 spacecraft, which flew past the planet in 1986 and is now the farthest man-made
object in the solar system. This image was taken through three color filters and recombined to produce the color image.
Neptune's moon Triton - the coldest place!
Triton has a surface temperature of -235 °C (-390 °F) and is considered the coldest place in our solar system.
It is so cold that most of Triton's nitrogen is condensed as frost.
About the same size and density as Pluto, Triton, one of Neptune's eight moons, is 30 times as far from the sun as the Earth.
It is very cold and windy, with winds close to the speed of sound, and has a mixed terrain of icy regions and bare spots. Triton
is a bit smaller than our moon, but its gravity is able to keep an atmosphere from completely escaping because it is so cold.
Recenly, a Massachusetts Institute of Technology researcher reported that observations obtained by NASA's Hubble Space Telescope
and ground-based instruments reveal that Triton, seems to have heated up significantly since the Voyager space probe visited it in 1989.
The warming trend is causing part of Triton's surface of frozen nitrogen to turn into gas, thus making its thin atmosphere denser.
"At least since 1989, Triton has been undergoing a period of global warming. Percentage-wise, it's a very large increase," said
Elliot, professor of Earth, Atmospheric and Planetary Sciences and director of the Wallace Astrophysical Observatory. The 5 percent increase on
the absolute temperature scale from about minus-392 degrees Fahrenheit to about minus-389 degrees Fahrenheit would be like the Earth experiencing a
jump of about 22 degrees Fahrenheit.
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. Credits: NASA/JPL/USGS
Auroras On Alien Worlds Can Be Stunningly Beautiful
Auroras on Earth are stunning to watch, but have you ever wondered what they might look like on other planets?
We took a journey to some alien worlds to find out what auroras look like there.
There is no doubt that extraterrestrial auroras can be very beautiful on other places in the Universe, and sometimes this light show can be very unique.
Explaining How An Aurora Is Created
Most of us enjoy to watch the beautiful lights in the night sky known as aurora.
These wonderful light display appears primarily over the polar regions. But what exactly causes the aurora?
Radio Emission From Ultracool Dwarf Detected By Arecibo Telescope
The Arecibo Telescope in Puerto Rico has discovered sporadic bursts of polarized radio emission from the T6.5 brown J1047+21.
Because Arecibo is a single, fixed-dish telescope, it has a restricted practical sensitivity to weak, quiescent emission from radio sources...
Invader From Another Galaxy
This alien intruder from another galaxy is in many ways different from other exoplanets observed by astronomers.
Located about 2000 light-years from Earth in the southern constellation of Fornax (the Furnace), the Jupiter-like planet orbits a dying star of
extragalactic origin and risks to be engulfed by it.
Power To See Most Distant Objects In The Universe
The 3C294, is one of the most distant galaxies recorded by Chandra, the most sophisticated X-ray observatory ever built.
The cluster 3C294 is even 40 percent farther (!) than the next most distant x-ray galaxy cluster.
Chandra focus on X-rays from high-energy regions of the Universe and see the invisible.
It is so sensitive that it can capture images of particles as they disappear into a black hole deep in outer space.
"Pillars Of Creation" Are Gone
Every time you look at the beautiful and famous image of the Pillars of Creation taken by Hubble back in 1995,
you are actually admiring something that no longer exists.
In fact, the Pillars of Creation were already long gone by the time the image was captured!