Signs of ancient erosion—most likely caused by liquid water—are preserved in the Ares Vallis outflow channel, a feature that meanders for more than 1,056 miles (1,700 kilometers) across the southern highlands of Mars.
Above, an angled view of part of Ares Vallis shows streamlined "islands," which indicate which way water likely moved in the channel.
The high-resolution image, recently released by the European Space Agency, was taken from about 185 miles (300 kilometers) above the surface by the Mars Express Orbiter.
Image courtesy ESA/DLR
An artist's concept of a pulsar—a fast-spinning neutron star that sends out beams of radiation from its poles—is superimposed on a Hubble Space Telescope picture of the Crab Nebula in a newly released image.
The cloud of gas is the remnant of a massive star that went supernova, dazzling sky-watchers on Earth who saw light from the blast in 1054. It was already known that the dense core of the dead star, called a neutron star, sits at the center of the Crab Nebula.
A lunar halo circles the moon over the Kilauea volcano's caldera in Hawaii on October 8.
Lunar halos form when moonlight interacts with the pencil-shaped ice crystals in thin, wispy cirrus clouds, according to NASA. Since the crystals have no particular orientation, the refracted light forms a circle around the moon.
On his way back to his car after searching for lunar rainbows, photographer Sean King threw one last look over his shoulder and "all of a sudden it looked like the moon started pulling clouds into a ring around it," he recalled.
The young star cluster NGC 1333, pictured above, is full of "failed" stars, according to astronomers using the Subaru Telescope in Hawaii and the Very Large Telescope in Chile.
Recent deep surveys conducted with the two telescopes revealed more than two dozen new brown dwarfs between NGC 1333 and the rho Ophiuchi star cluster. Brown dwarfs are free-floating objects several times the mass of Jupiter that glow brightly in their youths but are not massive enough to ignite nuclear fusion in their cores. (See "Coldest Star Found-No Hotter Than Fresh Coffee.")
The researchers were surprised to find that, when they added their finds to previously known brown dwarfs, NGC 1333 appears to harbor half as many of these astronomical oddballs as normal stars.
Image courtesy SONYC/Subaru
Lights Over Iceland
Auroras light up the sky over Njardvik, Iceland, on October 9.
This "eerily beautiful phenomenon," as photographer Olgeir Andresson described the aurora, is triggered when charged particles from the sun slam into Earth's magnetic field.
As solar particles get funneled along Earth's field lines toward the Poles, they collide with molecules in the atmosphere, infusing them with extra energy. The molecules in turn release the energy as light.
The Martian landscape stretches out like an ancient Roman road in a picture taken by the NASA rover Opportunity as it approached Endeavour Crater. The picture is one of 309 images included in a newly released video of Opportunity's journey from Victoria Crater to Endeavour.
Moving carefully and stopping occasionally to investigate interesting features, the aging rover took three years to travel 13 miles (21 kilometers).
Image courtesy Caltech/NASA
Carrying a French-made communications satellite, China's Long March-3B rocket carrier blasts off from the Xichang Satellite Launch Center in the country's southwestern Sichuan Province on October 7.
The European Eutelsat-W3C satellite will provide new capacities for broadcasting, telecommunications, and broadband services, according to China's state-run news agency Xinhua.
Like branching blood vessels, the rivers and streams of the Yukon Delta flow toward the Bering Sea in a recently released picture taken by NASA's Landsat 7 satellite.
The Yukon River originates in British Columbia, Canada, and travels through Yukon Territory before entering Alaska, according to NASA's Earth Observatory. In southwestern Alaska, the Yukon Delta spreads out in a vast tundra plain.