Cassini spacecraft one of NASA's star robots

Mimas, the smallest of Saturn's inner moons, casts its shadow into the outer rings of the planet. Equinox on Saturn, when the Sun crosses the plane of the Ringed Planet's equator, and day and night are of equal length, occurs about every 15 years. In the few months before and after Saturn's equinox, several of the planet's inner moons cast shadows on its rings.

 

With Saturn and Earth at the closest point to each other in their orbits around the Sun, spectacular views of the Ringed Planet will be possible for the next few weeks using even a small telescope. But the best views of Saturn and its moons over the past decade have been from the Cassini spacecraft designed by NASA and European space agencies.

The Cassini-Huygens mission and the Mars rovers are star performers in NASA's drive to explore the solar system with robotic technology. Cassini has been exploring Saturn and its moons since 2004, deploying the Huygens lander in 2005 for a successful touchdown on Saturn's surface and sending thousands of images back to Earth since.

Manned spaceflight has many allures, but robotic space missions will have far longer reach at far lower cost for the foreseeable future.

Saturn is the second-largest planet in the solar system, with hallmark rings and more than 60 moons. /NASA images

Time progression images show a storm in Saturn's northern hemisphere raging for more than 18 months.

Saturn's dense, murky atmosphere serves as a backdrop for Rhea, the Ringed Planet's second-largest moon. This view from Cassini looks toward the rings at a 1 degree angle, making the unilluminated side of the rings appear to be a solid straight band.

An infrared image shows a ring of aurora stretching around Saturn's north polar region. Cassini also has captured images of massive hurricane-like storms swirling at Saturn's poles.

The Sun reflects off a liquid methane sea on Titan, the Ringed Planet's largest moon. Titan and Earth are the only known places in the solar system with bodies of liquid on their surfaces.

Twisted fissures show the effect of powerful tectonic forces on Saturn's moon Enceladus.

 

Saturn's largest moon, Titan, appears deceptively small compared to Dione, Saturn's third-largest moon, in this image captured by Cassini.

Titan rises over the Ringed Planet's horizon. Tethys, a relatively small member of Saturn's large and various extended moon family, is a shiny ball of ice spinning around the gas giant.

Democracy, civil liberty and the War on Terrorism

Heavily armed police set up a perimeter around an apartment building in Watertown, Mass., during the manhunt for Boston Marathon bombing suspect Dzhokhar Tsarnaev. /Image via deadspin.com

It appears Mayor Tom Menino and other top officials made good decisions in the manhunt for the Boston Marathon bombing suspects, including essentially declaring martial law in Watertown and "shutting down" Boston.

I don't know whether to feel deeply grateful or deeply troubled.

One of the legacies of 9/11 is an unprecedent capability for federal, state and local government to declare and enforce martial law. There were hundreds, if not thousands, of police officers and National Guard members on the streets of Watertown in less than 12 hours.

I hope our political leaders keep making good decisions with their new police state powers.

Humanity pushing Earth to environmental brink

With humanity's population ballooning to about 7 billion and industrialization spreading to every corner of the planet, Earth's environmental systems are under severe stress from human activity. The evidence is plain to see on every continent and in every ocean.

Climate change has been linked to mass bleaching of coral throughout the Great Barrier Reef off the coast of Australia. /Image via npr.org

Smog from coal-fired power plants and other air polluters has become a persistent problem in several Chinese cities, including Beijing. /Image via theatlanticcities.com

The Deepwater Horizon oil spill has affected most if not all animal and plant species in the Gulf of Mexico, from pelicans and other wildlife slathered in slicks to contaminated coastal marshes. /Image via huffingtonpost.com

Logging is a prime cause of deforestation in the Congo River Basin, a global treasure that sustains the second largest rainforest in the world. /Greenpeace image

Climate change and habitat loss have decimated gold frog and toad species in Central America. /Image via nashvillezoo.org

Habitat loss has taken a heavy toll on elephant populations throughout Africa and Asia, shattering communities of animals known to have complex social bonds. /Image via eletracker.wordpress.com

Climate change has been linked to widespread melting of glaciers and sea ice in Antarctica, above, Greenland and the Arctic. The melting of ice in these regions is expected to drive dramatic sea level increases that pose a grave threat to coastal cities around the world. /Nasa image

Polar bears have become a poster child for climate change. With the sharp drop in Arctic sea ice, there have been reports of polar bears drowning after swimming many miles in fruitless attempts to hunt seals. /Getty image

No lifeboat: Earth is humanity's hope for the future

On April 22, 1970, a crowd of environmentalists and other activists gathers in New York City to rally for the first Earth Day. /Image via Hulton Archive

Humanity could not exist without its lush green and blue planet Earth. In comparison, the other planets in our solar system are barren wastelands. We would likely have to burrow under ground to colonize the Moon and Mars.

Earth is humanity's only hope for the future, the basis upon which all our hopes and dreams rest. Understanding and protecting Earth's atmosphere is one of the greatest collective challenges facing our species. Human civilizations thrive when the temperature is just right, ice ages and epic droughts leave their mark with the death of millions.

Humanity came to life on Earth, and life will never be better for humanity than on Earth.

And Earth is hurtling through the endlessly cold darkness of space alone. Ignoring good stewardship of the planet poses enormous risk on a global scale.

Earth viewed over a Moon horizon during NASA's Apollo 8 mission in December 1968. Apollo 8 was humanity's first visit to another world, establishing the capability to travel to the planet's nearest neighbor and gathering photos of the Moon's desolate surface. /NASA image

Republicans missing political revival mark

U.S. Sen. Kelly Ayotte fires an assault rifle at the opening of a firearms accessories factory in Keene, N.H. The Granite State Republican, who is a possible 2016 White House candidate, helped shoot down a Senate proposal this week for universal background checks on all gun purchases. /Union Leader photo by Meghan Pierce

After polling poorly with everyone except white men in the November 2012 elections, Republicans engaged in collective hand-wringing over broadening the party's appeal. The party's race to become competitive before the 2014 congressional elections has started with Republican lawmakers in Congress stumbling to their knees out of the gate:

• Couldn't or wouldn't cut a deal to stop the meat-axe "sequester" federal budget cuts, which have slowed the job market and probably weakened economic growth overall
• Blocked universal background checks for all gun purchases
• Made little progress on immigration reform

President Obama is off to a good start politically in his second term, without having to do too much. Only 20 months until the midterm elections.

Chechen war children grow up to be monsters

Grozny, the capital of Chechnya, was a flashpoint in both of the Chechen separatist wars with Russia that followed the fall of the Soviet Union. Street battles, artillery shelling and aerial bombardment in the mid-1990s, and again in 1999 and 2000, leveled the city. /Image via historyofrussia.org

After variously simmering and exploding into violence over the past 20 years largely out of the media spotlight, the breakaway regions of the Russian Caucasus have become a focal point of the biggest story in the world.

It's too early to say whether the brothers accused in the Boston Marathon bombings, Tamerlan and Dzhokhar Tsarnaev, were radicalized by the fighting in their homeland. But it's unlikely they would have been in the United States were it not for the struggle between Russia and separatists in Caucasus regions such as Chechnya and Georgia.

Two wars have been fought in Chechnya since the fall of the Soviet Union. Russian President Boris Yeltsin waged the first from 1994 to 1996, and Vladimir Putin started the second as part of his rise to power in 1999. Intense fighting into 2000 was followed by years of Russian counterinsurgency warfare that ultimately led to relative stability under President Ramzan Kadyrov, who has been accused of running Chechnya as a brutal dictator.

Horrific warfare, human rights abuses and political assassinations have been hallmarks of Chechen life for the past two decades. Two children of this war-scarred generation apparently grew up to be the monsters of the Boston Marathon bombings.

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Blogger-activist's trial dangerous Putin political stunt

In one of several outdoor adventure stunts, Vladimir Putin prepares to fly an ultra-light aircraft to lead the migration of a rare Siberian crane. /Image via telegraph.co.uk

Russian President Vladimir Putin has projected a strongman image for years: KGB colonel, Judo expert, hunter, swimmer, pilot, equestrian, fisherman and ruthless Kremlin leader worthy of a leading role in a James Bond movie. Although Putin's publicity stunt machine has misfired recently, the St. Petersburg native has thus far passed the greatest test in Russian politics: time. Putin has held sway in the Kremlin directly or indirectly for more than a dozen years.

One of Putin's most vocal critics, anti-corruption blogger Aleksei Navalny, faces upto 10 years in prison on embezzlement charges that are viewed as at least politically tainted, and at most politically directed. Local prosecutors dismissed the charges against Navalny, but federal prosecutors revived the case after the 36-year-old helped lead huge Moscow street protests against Putin's government in 2011.

The attempt to use the federal courts against a political opponent is ominous even by Putin's Bond villain standards. The strongman is playing with fire. Domestically, Putin runs the risk of cementing Navalny's status as the top opposition leader in the country. Internationally, the trial is publicizing a top concern about Russia's new market economy: corruption.

For the past five years, Navalny has exposed graft at major Russian companies and natural resources monopolies, including:

• VTB Bank's oil drill purchase scam estimated at $156 million
• Transneft's Chinese oil pipeline embezzlement estimated at $4 billion
• Federal government fraud such as rigged contracts documented at $56 million

It's not the kind of image Putin is looking to project.

Since 2000, Vladimir Putin has led Russia out front as president and from behind the scenes as prime minister. Fit and crafty at age 60, he could easily surpass Leonid Brezhnev as the longest serving leader of post-Stalinist Russia. /Image via AP

Putin has fostered a virile outsdoorsman persona, including equestrian excursions, hunting and fishing. /Image via telegraph.co.uk

Putin's "release" of a snow leopard led to an admission that his animal publicity stunts are shameless publicity stunts. The animal, one of the most isolative known in nature, was kept in a cage for a week for Putin's photo op. /Image via telegraph.co.uk

Movie-goers would love seeing Putin playing himself opposite Roger Craig in the next Bond film. /Image via itv.com

American War on Terrorism's Heartbreak Hill

Emergency workers respond to the bombing of the 2013 Boston Marathon finish line. /AP photo Charles Krupa
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This leaves a dent in the American way of life.

Just as 9/11 ruined the illusion of being safe in the workplace at our biggest cities, the Boston Marathon Bombing has ruined the illusion of being safe at our biggest entertainment events.

In U.S. spectatorship, the Boston Marathon is second only to the Super Bowl.

With three dead and more than 170 injured, the Boston attack ranks among the worst bombings in Iraq, Afghanistan or any other front in War on Terrorism. The bombs appear to have been placed at ground level and were loaded with nails and pellets to maximize lethality.

With no one immediately taking responsibility, it's sobering to ponder who among America's enemies could have perpetrated this Boston bloodbath. At least a half dozen suspects come to mind, after al-Qaeda, both foreign and domestic.

One of the worst outcomes of the hours, days and weeks after this atrocity would be a rush for revenge. Only justice can heal those scarred in the Boston bombing, and there can be no rush to justice.

I lived for several years near the Natick Town Common, where the marathon course crosses through one of the last bastions of Main Street America. It's hard to imagine being anywhere on the course now without the bombing crossing our minds.

Marathon madness: Terrorist attack shocks America

A bomb explodes Monday near the finish line of the Boston Marathon. With at least three dead and more than 100 injured, the bombing of Boston's cherished running event is the worst terrorist attack on U.S. soil since Sept. 11, 2001. /WBZ-TV image

Monday's bomb attack on the Boston Marathon is a reminder that the United States faces an insidious struggle with domestic and foreign terrorists. Whoever is responsible for the marathon bombings can expect retribution akin to the U.S.-led invasion of Afghanistan that followed the 9/11 terrorist attacks on New York City and the Pentagon.

Venezuela's socialist experiment enters new phase

Nicolas Maduro celebrates his narrow, 50-49, victory Sunday in Venezuela's presidential election. The hand-picked successor of Hugo Chavez edged opposition leader Henrique Capriles by about 300,000 votes. /Image via npr.org

The socialist experiment in Venezuela continues, with Nicolas Maduro, who served as foreign minister and vice president under Hugo Chavez, winning an incredibly thin victory in Sunday's election. Maduro has pledged to follow in his mentor's footsteps. But his country is politically polarized as well as facing a host of domestic economic and social problems.

Chavez's so-called socialist revolution is at a crossroads. Power outages are frequent in a country with the largest known oil reserves in the world. Capriles ran his campaign almost entirely on the government's mismanagement, waste and corruption as steward of the $1 trillion in oil production revenue generated during Chavez's 14 years as president. NPR reports: "Venezuelans are afflicted by chronic power outages, crumbling infrastructure, unfinished public works projects, double-digit inflation, food and medicine shortages, and rampant crime."

With such a narrow margin of victory and such widespread abuse of public office, Maduro would be wise to heed Capriles' call to clean up the government. Finding Capriles a ministry post would be a good start.