How far can you see?

Are you interested in the stars (I don't mean Hollywood's superficial celebreties)? Have you ever wondered how far away they are? Do you think you need a lot of fancy equipment to see anything meaningful in the sky? Well, despair not, you too can be an "astronomer", and all you need is your eyes (and a clear sky).

The picture you see here is a simulation of a section of the nighttime sky as it appears at about 11pm at this time of year (created by a planetarium program called Starry Night Pro Plus, available at http://www.imaginova.com/). Click on the picture to see it enlarged. If you step outside at around that time of night and look up straight overhead, you'll see at least the three brightest stars shown here. They are labelled Vega, Deneb, and Altair. You can draw some imaginary lines between the three to form what's known as the "Summer Triangle", most readily seen in the summer and fall months.

All three stars are a lot bigger than our own sun, and, although they appear to be of similar brightness, they are located at vastly different distances from us. Vega, the brightest, is located at a distance of about 25 light years, Altair is about 17 light years away, and Deneb can be found at a distance of about 1,500 light years.

This begs a question. What, exactly, is a light year? The first thing to realize is that it represents a distance. How is that defined? Well, a light year is the distance that light travels in one year. The speed of light has been measured very accurately, it's just about 300,000km per SECOND. This means that light can travel around the Earth (circumference 40,000km) more than 7 times per second. There are about 31.5 million seconds in a year - so the distance of one light year is 31.5 million times 300,000km; it's a tremendous stretch. You do the math.

Since Deneb is 1,500 light years away, it took light 1,500 years to cover that distance. When the light we see now left Deneb, the holy Roman empire had just about disintegrated, and we were beginning to enter what has been called a cultural wasteland: the "dark ages". Similarly, the light which left Altair and Vega has travelled for the same number of years as they are distant (measured in light years, again). It's hard to imagine that Deneb is almost 100 times farther away than Altair, yet they appear almost equally as bright from Earth. What a tremendous difference exists between individual stars. We'd be fried instantly, if Vega were located as close to us as our own sun.

You can see that when you look at the stars, you are also looking backward in time. For all we know, these stars may have exploded by now (a common occurrance for huge stars); we won't know that until 25, 17, or 1,500 years from now, respectively.

What were you doing at the time the light left the stars mentioned?

You can understand the sky without any special equipment - you can see things that are a long way off. Your eyes and an open mind are all that's required. To really appreciate the grandeur of the universe, though, you ought to find a truly dark sky - a location away from the pervasive light pollution which wipes out all the faint stars in our cities.

Classics

When the weather is nice, many people exhibit treasures which they would not want exposed to rain. One such category is that of classic cars. Beautifully maintained, they hark back to an age when driving was courteous, considerate, and far less aggressive. Some have lines that would be a wonderful fit for today's high tech wonders, others reflect the society of yore. In short, they're "classic". We thought that we should have a look at these - there is an "old car" show on in town at the moment.

My wife and I fit right in. Those years in which these beauties were manufactured were our "young" years, and I think that the pleasure of driving was far more appreciated then. We certainly had our (usually clean) fun, and were perhaps more aware then today's young folks regarding the responsibilities of being in charge of these big machines. Be that as it may, our generation is likely to be considered as "backward" as these vehicles; our internal "guts" probably work with the same degree of efficiency. We need as much or more ongoing maintenance - we're "classic", too.

Grandparents' joys

One of the joys and privileges of being grandparents is that you are allowed to spoil your grandchildren, and have fun doing it. Therefore, we took advantage of the fine weather today and invited our granddaughters Marina and Lauren to our annual, local fair, called the Pacific National Exhibition. Perhaps saying that our granddaughters intimated that an invitation would not be resisted approaches the truth even more closely.

The PNE started about a century ago as an agricultural fair, with a small amusement park (Playland) on the side. Well, Playland has become the main reason why people attend it; Marina and Lauren naturally came for the same reasons - the rides and games.

One of the cultural parts of the exhibition outside Playland was really classy - the acrobats from China were amazing. We all enjoyed that.

Of course this also became a "junk food day" - every now and then you have to forget about the restrictions you face as a senior.

As grandparents, we had a lot of fun watching the granddaughters screaming their way through the many rides they went on. It also brought back memories of our own "young" PNE days.




This was very much a fun (and exhausting) day.

Surprising interest

Over the years, I've participated in many a public astronomy night, where we we would take our telescopes and set up for public viewing. Invariably, everyone attending was impressed, sometimes awestruck, often incredulous as to the things one can see through a telescope. In my mind, the people who show up at these events always have a keen interest in astronomy, and they know it. They make the effort to come. Conversely, I thought until now that people who didn't show did not have that kind of curiosity, or didn't think of it as being important, if they had heard about the event.

Since I started my blog just a little over a month ago, I think that there are not many readers of it around. Considering that, a fair percentage of comments come back to me. To my surprise, my post about the recent lunar eclipse brought some responses which make me think that many people would like to know more about what can be seen "up there", without having any specialist knowledge in that regard.

There are some easy ways to do these things yourself - without any special equipment. Naked-eye astronomy, astronomy using binoculars, basic cameras.... one can do a lot in that regard. If there is enough interest, I can occasionally do a post about this.

The Moon hiding

This is the setup used for the eclipse pictures shown below. There was a constant, varying haze in the sky, necessitating some exprimenting with exposure times. The final phases were not captured, because solid clouds obscured the Moon in the end.


















As mentioned before, this morning a total eclipse of the Moon occurred. I woke up just in time to witness and photograph the event. The above image shows the Moon just disappearing into the Earth's shadow.


This shows the Moon when it had moved well into the Earth's shadow:




The orange tint is the result of the sunlight refracted around the Earth. As seen from the Moon, the Earth would seem to be surrounded by a "ring of fire" of this orange colour. It's like a sunset, except as seen from far away in space, with the whole Earth blocking the Sun.









The Moon is now at midpoint of the total eclipse:





Taken with a Canon Rebel XT through a Celestron C90 telescope at f11 (= a 1000mm focal length telephoto lens - see top image) and an exposure time of 3.2 seconds, sensitivity at 800 ASA.

Added on Aug 31:
You'll notice that the Moon does not appear quite sharp in one direction here. The cause is the Earth's rotation.

There is a faint image of a star streak close to the left edge of the image. The length of this streak tells you how much the image shifted due to this motion during the 3.2 seconds. If I had used my "equatorial" mount, and attached the telescope and camera to it, there would have been no "smear"; that type of mount compensates for the rotation, and is used for those astronomical photos which require many minutes or hours of exposure time.


Leaving the Earth's shadow:
f11 at 1/20 sec
















f11 at 1/160 sec

Eclipse of the Moon

On the morning of August 28, 2007, the full Moon will move through the Earth's shadow. This event is not rare, it is the second such event this year. This one, however, takes place at a time when the Moon is above the horizon for North and South America, the Pacific Ocean, and countries around the Pacific Rim. While the eclipse can be seen from beginning to end in the Pacific Ocean and the West coast of North America, the remainder of the locations mentioned above will at least see a part of it, while some of it occurs after the Moon sets (Eastern North America, all of South America), or before the Moon rises (Eastern Asia, Western Australia).

The various phenomena that occur on the Moon are seen simultaneously in all areas mentioned; the various locations have their own local time, of course. There is a worldwide standard time called Universal Time (UT), which is used to relate all world-wide phenomena and activities. For instance, the computer systems in the financial world have to be based on this time reference, in order to maintain the relationships of financial transactions. Other uses for an agreed-upon, common time reference are found in transportation and travel scheduling, this common reference is of importance to us here, in science, too - astronomy in this case. So here is the UT sequence of events for this Lunar Eclipse:

Penumbral eclipse begins (the first imperceptible darkening of the Moon) 7:53:39 UT
Partial eclipse begins (the main Earth shadow begins to cover the Moon) 8:51:16 UT
Total eclipse begins 9:52:22 UT
Greatest eclipse 10:37:22 UT
Total eclipse ends 11:22:24 UT
Partial eclipse ends 12:23:30 UT
Penumbral eclipse ends 13:21:01 UT

(all times taken from the Observers' Handbook of the Royal Astronomical Society of Canada, Toronto, Ontario, Canada)

UT is sometimes stated as Greenwich Mean Time (GMT). The various locations on Earth have their local time assigned based on their geographical "time zones". For North America, these time zones are 4 to 8 hours (East to West) "behind" UT. For instance, the Greatest eclipse for the West coast of North America, stated in Pacific Standard Time (PST) is 10:37:22 UT - 8 = 2:37:22 PST. An added complication is the use of daylight saving time. This adds an hour to the Standard Time in each time zone. So, for the above example, the Greatest eclipse occurs at 3:37:22 in the morning.

This event requires no telescope - the naked eye does a great job here. Any pair of binoculars will enhance the experience; in fact, for me, binoculars are the preferred means by which to view this event. Photography is relatively easy, but use a tripod and your optical zoom or zoom lenses to their maximum extent. The Moon appears surprisingly small in pictures taken with standard focal length lenses.

For an observer on the Moon, this event would look similar to this image of the planet Saturn, as seen from the Cassini probe - minus the rings.

Galaxies collide

In 2003, a special camera telescope, named the "Spitzer" telescope, was launched to record data from faraway space in those spectral ranges which cannot be explored from inside the Earth's atmosphere. This telescope is designed to "see" images in the spectral target range from near to deep infrared.



We perceive some wavelengths of infrared as heat. Infrared light can pass more readily through dust and gas clouds. Therefore it is possible to record things which cannot be seen in visual light (red to violet).



Spitzer has been spectaculary successful and has revealed many hitherto unknown phenomena in the universe. One such is the detection of a merger of four distant galaxies. Galaxy mergers are well documented. Our own galaxy will merge with the Andromeda galaxy in about 5 billion years (I'm not buying collision insurance for that).



The merger detected by Spitzer consists of four galaxies and is located at a distance of 5 billion light years. This means it actually occurred 5 billion years ago - light has just taken that long to reach us. By now this whole assemblage is probably one big, amorphous blob.



This is the image, which is a combination of images from several different telescopes, as described in the text caption.




Here is the text caption:

NASA's Spitzer Spies Monster Galaxy Pileup
For Release: August 6, 2007



Four galaxies are slamming into each other and kicking up billions of stars in one of the largest cosmic smash-ups ever observed.

The clashing galaxies, spotted by NASA's Spitzer Space Telescope, will eventually merge into a single, behemoth galaxy up to 10 times as massive as our own Milky Way. This rare sighting provides an unprecedented look at how the most massive galaxies in the universe form.

"Most of the galaxy mergers we already knew about are like compact cars crashing together," said Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "What we have here is like four sand trucks smashing together, flinging sand everywhere."

Rines is lead author of a new paper accepted for publication in Astrophysical Journal Letters.
Collisions, or mergers, between galaxies are common in the universe. Gravity causes some galaxies that are close together to tangle and ultimately unite over a period of millions of years. Though stars in merging galaxies are tossed around like sand, they have a lot of space between them and survive the ride. Our Milky Way galaxy will team up with the Andromeda galaxy in five billion years.

Mergers between one big galaxy and several small ones, called minor mergers, are well documented. For example, one of the most elaborate known minor mergers is taking place in the Spiderweb galaxy -- a massive galaxy that is catching dozens of small ones in its "web" of gravity.

Astronomers have also witnessed "major" mergers among pairs of galaxies that are similar in size. But no major mergers between multiple hefty galaxies -- the big rigs of the galaxy world -- have been seen until now.

The new quadruple merger was discovered serendipitously during a Spitzer survey of a distant cluster of galaxies, called CL0958+4702, located nearly five billion light-years away. The infrared telescope first spotted an unusually large fan-shaped plume of light coming out of a gathering of four blob-shaped, or elliptical, galaxies. Three of the galaxies are about the size of the Milky Way, while the fourth is three times as big.

Further analysis of the plume revealed it is made up of billions of older stars flung out and abandoned in an ongoing clash. About half of the stars in the plume will later fall back into the galaxies. "When this merger is complete, this will be one of the biggest galaxies in the universe," said Rines.

The Spitzer observations also show that the new merger lacks gas. Theorists predict that massive galaxies grow in a variety of ways, including gas-rich and gas-poor mergers. In gas-rich mergers, the galaxies are soaked with gas that ignites to form new stars. Gas-poor mergers lack gas, so no new stars are formed. Spitzer found only old stars in the quadruple encounter. "The Spitzer data show that these major mergers are gas-poor, unlike most mergers we know about," said Rines. "The data also represent the best evidence that the biggest galaxies in the universe formed fairly recently through major mergers."

Some of the stars tossed out in the monstrous merger will live in isolated areas outside the borders of any galaxies. Such abandoned stars could theoretically have planets. If so, the planets' night skies would be quite different from our own, with fewer stars and more visible galaxies.

In addition to Spitzer, Rines and his team used a telescope formerly known as the Multiple Mirror Telescope and now called MMT near Tucson, Ariz., to confirm that the four galaxies are intertwined, and NASA's Chandra X-ray Observatory to weigh the mass of the giant cluster of galaxies in which the merger was discovered. Both Spitzer and a telescope known as WIYN at Kitt Peak, also near Tucson, Ariz., were used to study the plume. WIYN is named after the University of Wisconsin, Indiana University, Yale University and the National Optical Astronomy Observatory, which own and operate the telescope.

Other authors of this paper include Rose Finn of Siena College, Loudonville, N.Y.; and Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics.

Whitney Clavin 818-354-4673Jet Propulsion Laboratory, Pasadena, Calif.

Take it when you can

We have guests from Europe at the moment and have taken the opportunity to show them around town a little. My sister and her husband invited us all to dinner yesterday, and a fine meal plus a beautiful view of the city was had by all.

Derek continues to gain strength and went to another appointment with his doctor yesterday. Nothing extraordinary needs to be done at this time, other than for him to gain some more weight. A good couple of days.

30 years

As you know from my previous posts, astronomy and related sciences and technologies are an interest of mine. 30 years ago, two spacecraft were sent out (Pioneer 1 and 2), which are still operating now, sending information about the very farthest reaches of our solar system and beyond. Here's a copy of the NASA news relating to this event:

-start

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.kintera.org/TR.asp?a=foJMIRNwFcJKJ4K&s=kqJTJZMFJhLLIXPLG&m=hmJXIiP0JoIcH

Contacts: Carolina Martinez/Jane Platt 818-354-9382/0880
Jet Propulsion Laboratory, Pasadena, Calif.
http://www.kintera.org/TR.asp?a=irKSI0OILfIRKeJ&s=kqJTJZMFJhLLIXPLG&m=hmJXIiP0JoIcH, http://www.kintera.org/TR.asp?a=luIYJ9PUKiLYIoI&s=kqJTJZMFJhLLIXPLG&m=hmJXIiP0JoIcH

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
http://www.kintera.org/TR.asp?a=hgLQIXNELfIIK3J&s=kqJTJZMFJhLLIXPLG&m=hmJXIiP0JoIcH

News Release: 2007-092 Aug. 20, 2007

Pioneering NASA Spacecraft Mark Thirty Years of Flight

PASADENA, Calif. - NASA's two venerable Voyager spacecraft are celebrating three decades of flight as they head toward interstellar space. Their ongoing odysseys mark an unprecedented and historic accomplishment.

Voyager 2 launched on Aug. 20, 1977, and Voyager 1 launched on Sept. 5, 1977. They continue to return information from distances more than three times farther away than Pluto.

"The Voyager mission is a legend in the annals of space exploration. It opened our eyes to the scientific richness of the outer solar system, and it has pioneered the deepest exploration of the sun's domain ever conducted," said Alan Stern, associate administrator for NASA's Science Mission Directorate, Washington. "It's a testament to Voyager's designers, builders and operators that both spacecraft continue to deliver important findings more than 25 years after their primary mission to Jupiter and Saturn concluded."

During their first dozen years of flight, the Voyagers made detailed explorations of Jupiter, Saturn, and their moons, and conducted the first explorations of Uranus and Neptune. The Voyagers returned never-before-seen images and scientific data, making fundamental discoveries about the outer planets and their moons. The spacecraft revealed Jupiter's turbulent atmosphere, which includes dozens of interacting hurricane-like storm systems, and erupting volcanoes on Jupiter's moon Io. They also showed waves and fine structure in Saturn's icy rings from the tugs of nearby moons.

For the past 18 years, the twin Voyagers have been probing the sun's outer heliosphere and its boundary with interstellar space. Both Voyagers remain healthy and are returning scientific data 30 years after their launches.

Voyager 1 currently is the farthest human-made object, traveling at a distance from the sun of about 15.5 billion kilometers (9.7 billion miles). Voyager 2 is about 12.5 billion kilometers (7.8 billion miles) from the sun. Originally designed as a four-year mission to Jupiter and Saturn, the Voyager tours were extended because of their successful achievements and a rare planetary alignment. The two-planet mission eventually became a four-planet grand tour. After completing that extended mission, the two spacecraft began the task of exploring the outer heliosphere.

"The Voyager mission has opened up our solar system in a way not possible before the Space Age," said Edward Stone, Voyager project scientist at the California Institute of Technology, Pasadena, Calif. "It revealed our neighbors in the outer solar system and showed us how much there is to learn and how diverse the bodies are that share the solar system with our own planet Earth."

In December 2004, Voyager 1 began crossing the solar system's final frontier. Called the heliosheath, this turbulent area, approximately 14 billion kilometers (8.7 billion miles) from the sun, is where the solar wind slows as it crashes into the thin gas that fills the space between stars. Voyager 2 could reach this boundary later this year, putting both Voyagers on their final leg toward interstellar space.

Each spacecraft carries five fully functioning science instruments that study the solar wind, energetic particles, magnetic fields and radio waves as they cruise through this unexplored region of deep space. The spacecraft are too far from the sun to use solar power. They run on less than 300 watts, the amount of power needed to light up a bright light bulb. Their long-lived radioisotope thermoelectric generators provide the power.

"The continued operation of these spacecraft and the flow of data to the scientists is a testament to the skills and dedication of the small operations team," said Ed Massey, Voyager project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. Massey oversees a team of nearly a dozen people in the day-to-day Voyager spacecraft operations.

The Voyagers call home via NASA's Deep Space Network, a system of antennas around the world. The spacecraft are so distant that commands from Earth, traveling at light speed, take 14 hours one-way to reach Voyager 1 and 12 hours to reach Voyager 2. Each Voyager logs approximately 1 million miles per day.

Each of the Voyagers carries a golden record that is a time capsule with greetings, images and sounds from Earth. The records also have directions on how to find Earth if the spacecraft is recovered by something or someone.

NASA's latest outer planet exploration mission is New Horizons, which is now well past Jupiter and headed for a historic exploration of the Pluto system in July 2015.

For a complete listing of Voyager discoveries and mission information, visit the Internet at:

http://www.kintera.org/TR.asp?a=ktIWI6PQJiKPIdI&s=kqJTJZMFJhLLIXPLG&m=hmJXIiP0JoIcH andhttp://voyager.jpl.nasa.gov/

-end


The technology involved is mind-boggling. Here I am, sitting at a laptop, and capable not only of getting all this information over the internet, but am also able to disseminate this to anyone who cares to read my blog. Amazing!

12 years

Derek and Airdrie celebrated their 12th wedding anniversary yesterday. Hilkka and I could not be happier. We have a wonderful son and daughter-in-law, and two beautiful granddaughters; we truly wish them All the Best.

There is a cliché which has been stated so often that it has become perfunctory. In the present situation, though, with Derek fighting colon cancer, it has real meaning for us:

Many Happy Returns!

Hell frozen over

I've mentioned the Cassini probe, which has been orbiting the planet Saturn for about three years now, in a previous post. Among many other data, it has been sending a lot of information back about Titan, Saturn's giant moon (bigger than the planet Mercury), with its dense, other-wordly atmosphere.


I'm reproducing here the description found on NASA's Jet Propulsion Laboratory's site:


Saturn's mysterious moon Titan is one of the strangest and most Earthlike places in our solar system.
Larger than Earth's moon and the planet Mercury ... it's the only moon in our solar system that has clouds and a dense atmosphere, mostly nitrogen and methane.
Titan's surface remained shrouded in secrecy below the clouds until July 2004. That's when NASA's Cassini spacecraft arrived at Saturn. With its RADAR and infrared imaging instruments, Cassini was able to lift the veil on Titan.
What scientists saw on Titan's surface astonished them.
Here was a world that looked a lot like home. Its surface is complex and varied, with Earthlike features like riverbeds; vast deserts, covered in dunes; and hydrocarbon lakes. These are the first open bodies of liquid found anywhere in our Solar System, besides Earth.
On Jan. 14, 2005, scientists got an even closer look. The Huygens probe, built by the European Space Agency, parachuted through Titan's atmosphere, taking detailed measurements. The probe survived for several hours on the surface of Titan and returned stunning images.
In spite of their apparent similarities, the differences between Earth and Titan are even more extreme. If you stood on the surface of Titan, the pressure would be like standing at the bottom of a swimming pool. The temperature is minus 289 degrees Fahrenheit (minus 178 degrees Celcius), far colder than Antarctica.
While rocks on Earth are made of silicates, the rocks on Titan are made of water ice.
While Earth's lakes and rivers are filled with liquid water, Titan's flow with liquid methane. In fact, if free oxygen were also present, a single spark would send the entire moon up in flames.
Most scientists agree that life as we know it would be unlikely on this bizarre world. But the study of Titan, the most Earth-like body in the solar system will help us understand our own Earth and even help guide the design of future missions, like Terrestrial Planet Finder, that are designed to search for Earth-like planets beyond our solar system.
The exploration of Titan has only just begun. Over the coming years, Cassini will fly close to the moon several dozen more times, gathering additional data and images, and unlocking more secrets of this strange new world ... an alien Earth in our own solar system.

Here are a couple of pictures of Titan's topology, returned by the Huygens probe, which was carried along with Cassini, and was released into Titan's atmosphere to descend by parachute to the surface:








Building Our New View of TitanJune 1, 2007

This composite was produced from images returned on 14 January 2005, by ESA's Huygens probe during its successful descent to land on Titan. It shows the boundary between the lighter-coloured uplifted terrain, marked with what appear to be drainage channels, and darker lower areas. These images were taken from an altitude of about 8 kilometres with a resolution of about 20 metres per pixel.
Credits: ESA/NASA/JPL/University of Arizona







Huygens at Titan 1January 14, 2005

This raw image was returned by the ESA Huygens DISR camera after the probe descended through the atmosphere of Titan. It shows the surface of Titan with ice blocks strewn around.

It was taken with the Descent Imager/Spectral Radiometer, one of two NASA instruments on the probe.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The Descent Imager/Spectral team is based at the University of Arizona, Tucson, Ariz.
Credit: ESA/NASA/University of Arizona

You may also be interested in the following movie:

http://saturn.jpl.nasa.gov/news/features/feature20070129.cfm


Imagine, rocks made of ice, liquid methane rivers and lakes, "colder than hades".

If there is a hell frozen over, this is it.

An update

I see that Derek's not been posting for a couple of days. I'd like to assure everyone that he's doing ok. Last night he went to the Barcamp Vancouver and has gone again today. That's good news. It means to us that he has sufficient stamina to go through several hours of meeting and talking to people. Our niece is looking after the girls, and they've gone to a garage sale near our niece's home. We appreciate days like this.

Maybe there is life here, too?

Here's an image from the Galileo orbiter which circled Jupiter at the time. Europa is an ice-covered moon of Jupiter (in order of increasing distance from Jupiter: Io, EUROPA, Ganymede, Callisto). This picture shows a small area on Europa, bringing out the details of ridges, furrows, spots, all of which is much speculated about. The general consensus appears to be that there is an ocean of liquid water underneath all this, and that the observed phenomena relate to upwelling and gravitational warming of this ice ("squeezing" by Jupiter and those other moons). If there is water, is there a chance for some kind of "life"?

Original Caption Released with Image:
Reddish spots and shallow pits pepper the enigmatic ridged surface of Europa in this view combining information from images taken by NASA's Galileo spacecraft during two different orbits around Jupiter.
The spots and pits visible in this region of Europa's northern hemisphere are each about 10 kilometers (6 miles) across. 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.
The image combines higher-resolution information obtained when Galileo flew near Europa on May 31, 1998, during the spacecraft's 15th orbit of Jupiter, with lower-resolution color information obtained on June 28, 1996, during Galileo's first orbit.
The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. Additional information about Galileo and its discoveries is available on the Galileo mission home page at http://galileo.jpl.nasa.gov .
Image Credit:
NASA/JPL/University of Arizona/University of Colorado