Recent images taken by the Cassini spacecraft indicates that the highlands of Saturn's moon Titan may be riddled with caves.

The  Xanadu region of Titan is about 4000 kilometers (about 2500 miles) wide. While already though to be a highland area, Cassini's haze-penetrating radar shows that  the interior of the region is crossed by mountain ranges rising to a height of 1,000 meters (about 3,000 feet)  This contrasts with most of Titan's surface, which appears relatively flat.

"These are the highest mountains measured on Titan so far," says Cassini team member Ralph Lorenz of the University of Arizona in Tucson.

Radio waves bouncing off Xanadu indicate these mountains are not solid. They appear to have strange electrical properties – specifically a low "dielectric constant," which means they shouldn't be solid enough to stand.

"The only reasonable material makeup that could have a very low dielectric constant and still hold together enough to form the structures that we see would be some sort of porous stuff – most likely porous water ice," says another team member, Steve Wall of the NASA JPL in  Pasadena, California.

One theory is that the region is filled with caverns, possible carved out by the methane rain that is believed to fall on Titan.

Erosion from that rain would also form the long river valleys along the Xanadu region's edge. Cassini scientists theorize that these rivers carry ice grains down to the plains to form the dunes seen on much of Titan's surface.

There are also small, dark patches in this region. These may be methane lakes, although there little evidence of liquid still present on the surface. Evidence of liquid may be forthcoming, however.  This weekend, Cassini will take pictures of Titan's north pole, where lakes or seas to would be likely to exist, since the extreme cold would keep methane from evaporating into gaseous form.

You can view a Quicktime video of the the Cassini images here.

After almost half a century of intergalactic eavesdropping, Search for Extra-Terrestrial Intelligence (SETI) has yet to report any signs of contact. Does this mean we're truly alone? Or is SETI aiming at a dead spot in the universe? SETI senior astronomer Seth Shostak says a 46-year long search is not the same as a thorough one and, no, he doesn't think we're alone.

"The number of star systems we’ve carefully examined is only about a thousand. That’s a trifling sample compared with the several hundred billion suns that stud the Milky Way, and of little statistical significance. It’s comparable to initiating a quest for Americans who play the oboe, but considering the search meaningful after interrogating only two people," is how he described it.

It's no surprise Shostak gets a lot of email from folks with their own ideas on why SETI has turned up empty handed after all these years. He took the top four reasons and added his opinion to each:

1. "You’re counting on the aliens using communication technology (radio, light) that’s oh-so-last century. They will be far beyond this."

In other words, SETI’s technical approach is wrong. Some have suggested looking for gamma rays, gravity waves, or taking advantage of "hyperdimensional physics." Shostak says gamma rays are wasteful since they require enormous amount of energy per bit. Gravity waves are difficult to produce produce ("You need to shake planets or something similar") and hard to detect. In addition gravity waves is not known to move faster than the speed of light.

As for "hyperdimensional physics" Shostak says that might work if they knew what it was. He is not discounting using methods based on undiscovered laws of the universe that will allow sending of bits from one place to another more cheaply than light and radio, or faster. But they're waiting for someone to discover these new laws first before they adjust their experiment accordingly.

2. "If hi-tech societies or thinking machines were out there, they’d have colonized the Galaxy by now. Clearly, we’re alone… lone… lone."

The Fermi Paradox assumes that if sophisticated societies are common, they should also be ubiquitous. But if you look out the window and don't see large animals with long, prehensile noses does that mean elephants don’t exist on this Earth? "To use the Fermi Paradox as a reason for the lack of a SETI signal is to make a very big extrapolation from a very local observation. Seems chancy to me," say Shostak.

3. "The aliens don’t want to communicate with us. Look at what we’re doing to the planet!"

Shostak says this is a self-centered view to think that what we do to our planet would matter to them.

4. "You SETI types are just looking in the wrong places. We know where the extraterrestrials are: on a planet in the Zeta Reticuli system."

According to Shostak he likes this explanation the best, even though it’s the worst. Zeta Reticuli is the star system that was the supposed hometown of aliens who reportedly abducted social worker Betty Hill and her husband in 1961. The system’s identification is based on a "star map" Betty drew after their release. But Shostak clarifies that, as a matter of fact SETI did look at both of Z. Reticuli’s stellar components during SETI's observing run in Australia ten years ago and "the aliens, for their part, remained coy."

Trivia: what do thermonuclear blasts have that are similar to those of the sun's, only more powerful? The white dwarf. When paired in a binary system with a red giant (a dying, bloated star), the white dwarf will accumulate the red giant's dumped gas leading to a giant thermonuclear explosion also known as 'nova'.

The two-star system (like that of white dwarf and red giant) was dubbed as RS Ophiuchi and is a recurrent nova as it has occurred five times before.

As opposed to previous assumptions that RS Ophiuchi eject matter equally in all directions, recent studies show that the explosion evolved into two lobes with the nova producing twin jets of stellar material that spews out from the white dwarf in opposite directions.

As National Radio Astronomy Observatory astronomer Michael Ru pen said, "The radio images represent the first time we've ever seen the birth of a jet in a white dwarf system. We literally see the jet 'turn on'."

The nova may be a good sight to behold, but its beauty may mean that a more violent supernova explosion will occur in the future.

As objects in the universe push and pull against each other, spinning, orbiting, grazing and even (occasionally) colliding, they give off huge gravitational waves. Fred Raab, head of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in southeastern Washington State, plans to observe those waves as they crash against our terrestrial shores.

Raab says that since the invention of the telescope in the early 1600's, we've seen only "a small portion of what exists." He believes that LIGO can show us everything else.

Kip Thorne, a physicist at the California Institute of Technology, adds, "[LIGO] gives us an observational tool to probe the dark, strong-gravity part of the universe, which we've never really done."

Instead of observing light or radio waves or X-Rays directly, LIGO "feels" these things by measuring gravitational waves that ripple like water across a pond. The advantage here is that unlike light waves - which bounce off or can be blocked by solid objects - gravitational waves go through everything.

The ability to observe and measure these gravitational waves could very well change our entire understanding of the universe.

Aside from the eighth grade social studies student who thought "Seti" was an ancient Egyptian deity, many people have strange ideas about just what the Search for Extra Terrestrial Intelligence actually is, or what it does.

Some folks think its a "National Agency." This was promulgated by  a line in the movie Starman, in which a government official flashes a badge and announces "I'm from SETI."  Never let it be said that Hollywood lets facts stand in the way of a good movie.

The reality is that SETI is a field of research, carried on by a group of 30 scientists from several different countries. There is a SETI Institute - but no "National SETI Agency."

Another misconception is the idea that this is the primary purpose of radio telescopes. In fact, while SETI does make occasional use of these, these radio arrays spend 95% of the time observing quasars and other celestial phenomena.

The third misconception has to do with the length of time that SETI has been on the job. A common argument by politicians (not the best nor the brightest of people) wielding budget axes runs like this: "SETI has been listening for nearly fifty years and hasn’t discovered ET, so SETI is a failure."

As with many other issues, politicians making this statement demonstrate their ignorance about what SETI is and how it actually works. While SETI actually did go on-line in 1960, the search for alien intelligence has not been continuous over intervening decades. In fact, during the first twenty years, the twenty-three targeted SETI projects comprised a total of three months of actual search time.

It should also be noted that a "radio telescope" is not like your AM/FM Radio. It is an extremely precision, directionally-sensitive instrument, searching one ten-millionth of the sky at any given time, and over a very limited spectrum, running from 1GHz to 10 GHz containing about nine billion channels. Each sky position requires at least 90 observations to cover all of that "real estate."

One last point: not all SETI projects are given equal priority. To date, only two SETI projects have done any significant searching at all. (It's a big universe out there....)

China is gearing up for their moon probe! After predicting that their will be a manned lunar landing for China in 2024, China is now gearing to set up radio telescopes to monitor that country’s first lunar orbiter, Chang’e 1, according to Li Yan, director of the Chinese Academy of Sciences (CAS) Yunnan Observatory.

This monitoring project just goes to show that China is indeed more than capable of monitoring and tracking their future Moon-orbiting satellites. Spread out in distance from each other, the radio dishes are set up in Beijing, Shanghai, the southwestern Yunnan Province, and the northwestern Xinjiang Uygur Autonomous Region.

The testing was conducted in an agreement between the CAS and the European Space Agency. Every four hours, the satellite circled the Moon and the telescopes were able to detect half the orbit, or about two hours. This Moon probe is based upon the country’s Dongfanghong III satellite platform and other technology. Chang’e 1 is on track to be tested at the Xichang Satellite Launch Center in Southwest China’s Sichuan Province in December. If the probe’s readiness is green-lighted it will be launched in April 2007.

Aside from that, Chang'e 1 will also sport a stereo camera system that will chart the lunar surface, an altimeter to measure the distance between the spacecraft and the lunar surface, a gamma/Xray spectrometer to study the overall composition and radioactive components of the Moon, a microwave radiometer to map the thickness of the lunar regolith, and a system of space environment monitors to collect data on the solar wind and near-lunar region. From the looks of that alone, it seems that there is a lot on Chang'e 1's shoulders.

Scientists seldom call objects (or phenomena) by their descriptive qualities, but since they still don't know what exactly makes up dark matter, scientist still call it as such - DARK matter.

There are new theories though that suggest what dark matter is made of. An international team of researchers from Max Planck Institute for Radio Astronomy in Bonn and from University of California, Los Angeles say that dark matter MIGHT be composed of sterile neutrinos.

Dark matter may have been the key player in the creation of stars when the universe began. These scientists are suggesting that if such is the case, then dark matter might be made up of sterile neutrons since these speed up the creation of molecular hydrogen when they decay.

Such process could have lit up the first starsthat then ionised the gas around them, spawning new ones. This is just a theory they're testing, but it seems promising because of the neutrinos' connection to neutron stars, antimatter and dark matter.