A vanished glacier with a mysterious calling card suggests Mars went through many ice ages in its very recent past. A fresh look at images from the Mars Reconnaissance Orbiter indicates thick glaciers may have existed in the past 100 million years in the planet's equatorial region, but vanished after planetary wobbles changed the climate in certain areas. "We've gone from seeing Mars as a dead planet for three-plus billion years to one that has been alive in recent times," said Jay Dickson, a geologist at Brown University and lead author of the study. "[The finding] has changed our perspective from a planet that has been dry and dead to one that is icy and active."

There's a growing buzz in the astrobiology community that ancient hydrothermal springs may have been spotted on Mars. Thanks to the eagle-eyed work of Carlton Allen and Dorothy Oehler of NASA's Johnson Space Center, "spring-like" mounds have been found in Vernal Crater in Arabia Terra on the red planet. The high-powered zoom lens of NASA's Mars Reconnaissance Orbiter (MRO) has picked up the features - two possible ancient hydrothermal springs are viewed as light-toned, elliptical structures. The martian features have a striking similarity to spring mounds here on Earth, such as those in Dalhousie, Australia.

With its thin atmosphere and scant moisture, Mars is often largely cloud-free. But new observations reveal clouds of dry ice thick enough to cast significant shadows on the red planet. Dust storms are known to shroud vast swaths of Mars. Clouds have been photographed from the ground before, too. The new research finds that carbon dioxide, the main component of martian air, freezes into clouds so dense they dim the sun by about 40 percent. Frozen carbon dioxide is commonly called dry ice here on Earth.

The longstanding mystery of how oceans once formed on Mars could be solved by fire and brimstone. Specifically, researchers now suggest that ancient volcanoes could have released brimstone — now more commonly known as sulfur — that warmed up the red planet enough for liquid water oceans in the early days of Mars. These findings might also shed insight on the young Earth, including the origins of life, scientists added.

Simultaneous warming on Earth and Mars suggests that our planet's recent climate changes have a natural—and not a human-induced—cause, according to one scientist's controversial theory. Earth is currently experiencing rapid warming, which the vast majority of climate scientists says is due to humans pumping huge amounts of greenhouse gases into the atmosphere. Mars, too, appears to be enjoying more mild and balmy temperatures. In 2005 data from NASA's Mars Global Surveyor and Odyssey missions revealed that the carbon dioxide "ice caps" near Mars's south pole had been diminishing for three summers in a row. Habibullo Abdussamatov, head of space research at St. Petersburg's Pulkovo Astronomical Observatory in Russia, says the Mars data is evidence that the current global warming on Earth is being caused by changes in the sun. "The long-term increase in solar irradiance is heating both Earth and Mars," he said.

NASA scientists have discovered what might form some of the weirdest landscapes on Mars, winding channels carved into the Martian surface that scientists have dubbed "spiders," "lace" and "lizard skin." The unusual landscape features form in an area of Mars' south pole called cryptic terrain because it once defied explanation. But new observations from NASA's Mars Reconnaissance Orbiter, presented here today at a meeting of the American Geophysical Union, bolster theories that the intricate patterns may be sculpted by springtime outbursts of carbon dioxide gas from underneath the frozen-carbon dioxide polar ice cap.

Clouds over Mars contain less water than previously thought, according to new research using simulated clouds in a lab here on Earth. The clouds under study are made of water ice, like some clouds on Earth, said Tony Colaprete of NASA's Ames Research Center. "However, they are forming at very cold temperatures, often below minus 100 degrees Celsius (minus 212 degrees Fahrenheit)," Colaprete said "What we have found in our laboratory studies is that it is much harder to initiate cloud formation at these cloud temperatures than what we thought."

The sand dunes of Mars are in no rush to move across the red planet's surface, new research shows. It can take up to 1,000 years for dunes to move just a few meters on Mars, largely due to the planet's apparent lack of moving surface water, weak winds and thin atmosphere, said the study's author Eric Parteli. "Mars dunes move much slower than Earth's dunes," said Parteli, a researcher at the University if Stuttgart in Germany, in an e-mail interview. Parteli and colleague Hans Hermann, of Brazil's Federal University of Ceará, used computer simulations to reproduce actual Martian dunes observed by the Mars Orbiter Camera aboard NASA's Mars Global Surveyor spacecraft. The images were taken before Mars Global Surveyor went silent last year, ending its 10-year study of the red planet's surface.

Odd materials recently found on Mars have planetary scientists scratching their heads. That's because the materials were spotted at the red planet's equator—but they appear to contain a large amount of water like that previously seen only at the Martian poles. The finding is based on new high-resolution radar data from the Martian subsurface, which show similarities between the properties of deposits on a hilly equatorial formation called Medusae Fossae and the sediments at the ice-rich poles.

Mars appears to be a calm and desolate planet, but scientists now think something big is brewing beneath its wind-swept surface. New research on Hawaiian volcanoes, combined with satellite imagery of Mars, suggests that three Martian volcanoes may only be dormant—not extinct. Instead of Mars' crust moving over stationary magma "hot spots," as occurs on Earth, researchers think the plumes travel. "On Earth, the Hawaiian islands were built from volcanoes that erupted as the Earth's crust slid over a hot spot—a plume of rising magma," said Jacob Bleacher, a planetary scientist at Arizona State University and NASA's Goddard Space Flight Center in Greenbelt, Md. "Our research raises the possibility that the opposite happens on Mars; a plume might move beneath stationary crust."

A major dust storm has developed on the red planet, blocking sunlight and prompting Mars mission managers to keep a close eye on it, SPACE.com has learned. It is not known how large the storm might grow, but already it is thousands of miles across. If it balloons, as dust storms have done in the past, it could hamper operations of NASA's Mars rovers Spirit and Opportunity. For now, officials don't think the storm will threaten rover operations, however. In fact, the windy conditions on the planet have blown off large amounts of dust from the rovers' solar arrays, giving them more power. The power boost may lend a helping hand to the Opportunity rover, should officials decide to send it into Victoria Crater.

Since 1991, planetary scientists have floated the idea that Mars once harbored vast oceans that covered roughly one-third of the planet. Two long shore-like lips of rock in the planet's northern hemisphere were thought to be the best evidence, but experts argued that they were too "hilly" to describe the smooth edges of ancient oceans. The view just changed dramatically with a surprisingly simple breakthrough. The once-flat shorelines were disfigured by a massive toppling over of the planet, scientists announced today. The warping of the Martian rock has hidden clear evidence of the oceans, which in any case have been gone for at least 2 billion years. "This really confirms that there was an ocean on Mars," said Mark Richards, a planetary scientist at the University of California at Berkeley and co-author of the study, which is detailed in the June 14 issue of the journal Nature.

The planet Mars may well have a liquid center, scientists say. That's a surprise because Earth's core, which contains similar elements as Mars, has a solid, metal interior surrounded by a layer of molten metal. The discovery was made by a team of European scientists using a device called a high-pressure anvil, which is capable of producing pressures of up to 6 million pounds per square inch (40 Gigapascals). In experiments, the authors squeezed together high-temperature mixtures of iron, nickel, and sulfur to replicate conditions found on Mars. The researchers were able to determine that the Martian core is still mostly, if not entirely, liquid.

Earth's dusty neighbor Mars is grappling with its own form of climate change as fluctuating solar radiation is kicking up dust and winds that may be melting the planet's southern polar ice cap, scientists said Wednesday. Researchers have been watching the changing face of Mars for years, studying slight differences in the brightness and darkness of its surface. These changes in brightness have been generally attributed to the presence of dust, but until now their effect on wind circulation and climate has not been clear.

Shifting dust storms on Mars might be contributing to global warming there that is shrinking the planet's southern polar ice caps, scientists say. Computer simulations similar to those used to predict weather here on Earth show that the bright, windblown dust and sand particles affects Mars’ albedo—the amount of sunlight reflected from the planet’s surface. The research, detailed in the April 5 issue of the journal Nature, suggests these albedo variations play an important role in the climate of Mars. It could also potentially explain how global dust storms are triggered on the red planet.