Moqui Marbles and Martian Blueberries

The photo above shows Moqui Marbles in their native habitat of southern Utah. These curious rocks are actually concretions having iron (hematite) rinds.

Very similar rocks, called blueberries, have been observed repeatedly on Mars by the rovers. Click here to see an image taken by the Opportunity rover of the blueberries. Some scientific papers implicate the possibility of life on Mars playing a role in their formation while others do not.

Discussions about the pros and cons of their formation have been quite lively at times. However, the consensus seems to be that both the marbles and the blueberries were created beneath the surface as naturally occurring substances, most likely minerals, precipitated from flowing groundwater. Pictured with the marbles is a Devil’s-Claw cactus (Sclerocactus parviflorus). — Bret Webster

Bull Valley Slot Canyon and Truck Wreck

Over the years many Earth Science Pictures of the Day have featured slot canyons, remarkable landforms of the Southwestern United States and elsewhere. The slot canyon shown above is unique. In 1954, a highway accident claimed three lives when a pick-up truck tumbled off the road and into Bull Valley Slot Canyon in southern Utah. The arrows on the image point to the truck’s wheels that can still be seen high above the canyon floor.

Skutumpah Road crosses this slot canyon. The canyon is so narrow that boulders were wedged into the top of the canyon to support the rock-fill bridge seen from above in the second photo.

You might find it unusual that a bridge needs to be pointed out when photographed from only a few meters away. To show the location my wife Elaine is standing at the middle of the bridge and nearly 200 ft (60 m) directly above Bull Valley Slot’s deep floor. — Thomas McGuire

Double Pink Rainbow Over Glen Ashley, South Africa

The photo above showing a high-arching pink rainbow was captured at sunset near Durban, South Africa.

The camera is facing toward the anti-solar point. Like the setting Sun, the rainbow colors we’re familiar with acquire red or pink hues once the Sun dips close to the horizon. This is because as the Sun sets (or rises) the increased path length sunlight takes through the atmosphere acts to scatter out the green, blue and violet colors from our view. — Photo Jacques Joubert Summary Jim Foster

Antisolar Point

The point on the celestial sphere that lies directly opposite the sun from the observer, that is, on the line from the sun through the observer.

Volcanic Lightning

Image by Martin Rietze

It is thought that friction between particles and gases cause potential differences that create the lightning displays. [**]

February 19, 2013 Eruption of Mount Etna

Mount Etna, on the island of Sicily, Italy, has long been one of Europe’s most active volcanoes — eruptions have been observed here for approximately 3,500 years. The most recent series of eruptions were initiated during the early morning hours of February 19, 2013, when glowing fountains of lava erupted from Mount Etna’s southeast crater.

Life Confirmed in Buried Antarctic Lake

Blobs and smears of microbial life growing in clear plastic disks are confirmation of a community living in a lake buried beneath the Antarctic ice, scientists studying the lake have said.

Water retrieved from subglacial Lake Whillans contains about 1,000 bacteria per milliliter (about a fifth of a teaspoon) of lake water, biologist John Priscu of Montana State University told Nature News. Petri dishes swiped with samples of the lake water are already growing colonies of microbes at a good rate, Nature News reported.

Lake Whillans is 2,625 feet (800 meters) below the West Antarctic Ice Sheet. After breaking through the ice on Jan. 28, researchers are returning to the United States with 8 gallons (30 liters) of lake water and eight sediment cores from the lake bottom. These samples will be tested for signs of microbial life, which could shed light on the types of extreme life that is able to thrive in such harsh environments.

Now, I don’t want to get people too excited but just imagine what the results could imply for a future mission to the Galilean satellite, Europa.