Within our solar system, few worlds have much in common with Earth. Sure, Venus is about the same size, and Mars may have once (billions of years ago) resembled Earth in terms of its chemistry… But in many ways, Titan, the largest moon of Saturn, seems to be the world most similar to home.

This moon remained a mystery from the time of its discovery in 1655 until the Cassini/Huygens mission managed to peer beneath its veil of thick clouds in 2004. And that mission has made astounding discoveries.

Underneath its obscuring atmosphere, Titan looks shockingly similar to Earth: the lander saw dunes and valleys, as well as beaches and most surprisingly, seas!

We caught the glint of sunlight off these massive methane lakes before, but another near pass by Cassini has allowed us to make a radar map of the topography of Titan’s surface to get a sense of the depth of these alien oceans. It also provided a chance to build upon our understanding of how mountains and valleys here on Earth affect weather patterns around them.

And Cassini has also helped us understand Titan’s unusual atmosphere. A recent NASA press release describes how the moon forms a chemical mix near the surface “like L.A. smog on steroids.” The presence of complex aerosols has long puzzled scientists, but Cassini’s data provided clues to identify the missing link in the process: polycyclic aromatic hydrocarbons (PAHs). (The Academy’s planetarium director recently blogged about a diagram that accompanied that press release.)

Cassini is approaching ten years in orbit around the ringed planet, and its work continues. A future objective is to determine if waves occur on any of Titan’s three largest seas, not too far a stretch given the observations of massive dunes sculpted by wind, but astronomers are still working to piece together the delicate balance of wind, temperature, chemical composition, and viscosity of these alien shores.

Every pass gives us more information about Titan’s clouds and the world beneath them—fleshing out our knowledge of this most familiar-seeming moon.

Josh Roberts is a program presenter and astronomer at the California Academy of Sciences. He also contributes content to Morrison Planetarium productions.

Image: NASA/JPL-Caltech/SSI

The devastating earthquake was unusual in some ways: scientists in the field found no evidence of surface rupture on the source Enriquillo-Plantain Garden fault, certain areas believed to be on solid ground were hit harder than expected, and the resulting tsunamis surprised geologists because the lateral motion of strike-slip faults rarely cause tsunamis.

The first paper shifts the fault, literally. USGS and NASA/JPL scientists, working with others, used a combination of seismological observations, geologic field data, and satellite geodetic measurements to analyze the earthquake source. Their finding? The large earthquake resulted not from the Enriquillo fault, as previously believed, but from slip on multiple faults—primarily a previously unknown, subsurface fault.

In addition, because the earthquake did not involve slip near Earth’s surface, the study suggests that it did not release all of the strain that has built up on faults in the area over the past two centuries, meaning that future surface-rupturing earthquakes in this region are likely.

The second paper looks at the localized damage of the earthquake. After the major event, USGS scientist Susan Hough and her team set out seismographs that recorded aftershocks. Those recordings revealed that ground motions were amplified by the relatively young and soft rocks that underlie the valley in which Port-au-Prince lies. The strongest observed amplifications occurred along a narrow, steep foothill ridge in the city. That means that topography influenced the severity of aftershocks, too.

From the New York Times:

Seismologists know that local geology can also affect the severity of an earthquake… Now [this] new study finds that in addition to the underlying geology, the geometry of local surface features contributed to the earthquake’s intensity as well.

The study suggests that topographic effects should be considered when detailed hazard zone maps are made for other regions.

From OurAmazingPlanet:

Pinning down how topography amplifies an earthquake’s energy — be it by steepness or width of a ridge, for example — will take longer, said the authors, but the initial findings could help guide the rebuilding effort.

Finally, the third paper finds that the tsunamis did not direct result directly from the quake, but most likely arose from underwater landslides triggered by the shaking. An article in National Geographic Daily News wonders what this could mean for our own earthquake-prone state. The good news is that, according to the article, “the risk of tsunamis… has already been included in California’s preparedness plans.”

The more we understand about the science of this terrible event, the better prepared we’ll be whenever and wherever it happens next.

Image credit: NASA/JPL/JAXA/METI