This photo was captured from outside the enormous mouth of NASA’s giant thermal vacuum chamber, called Chamber A, at Johnson Space Center in Houston. Previously used for manned spaceflight missions, this historic chamber is now filled with engineers and technicians preparing a lift system that will be used to hold the James Webb Space Telescope during testing.
The James Webb Space Telescope is the scientific successor to NASA’s Hubble Space Telescope. It will be the most powerful space telescope ever built. Webb is an international project led by NASA with its partners, the European Space Agency and the Canadian Space Agency.
> Related: Amazing View of Engineers Preparing NASA’s Gigantic Space Simulation Chamber for Massive Test
Image Credit: NASA/Chris Gunn via NASA http://www.nasa.gov/content/space-simulation-chamber-prepared-for-testing-webb-telescope

Expedition 42 Flight Engineer Samantha Cristoforetti of the European Space Agency (ESA) took this photograph of the Alps from the International Space Station, and posted it to social media on Tuesday, Dec. 23, 2014. She wrote, “I’m biased, but aren’t the Alps from space spectacular? What a foggy day on the Po plane, though! #Italy”
Image Credit: NASA/ESA/Samantha Cristoforetti via NASA http://www.nasa.gov/content/view-of-the-alps-from-space

This new NASA/ESA Hubble Space Telescope image shows the galaxy IC 335 in front of a backdrop of distant galaxies. IC 335 is part of a galaxy group containing three other galaxies, and located in the Fornax Galaxy Cluster 60 million light-years away.
As seen in this image, the disk of IC 335 appears edge-on from the vantage point of Earth. This makes it harder for astronomers to classify it, as most of the characteristics of a galaxy’s morphology — the arms of a spiral or the bar across the center — are only visible on its face. Still, the 45 000 light-year-long galaxy could be classified as an S0 type.
These lenticular galaxies are an intermediate state in galaxy morphological classification schemes between true spiral and elliptical galaxies. They have a thin stellar disk and a bulge, like spiral galaxies, but in contrast to typical spiral galaxies they have used up most of the interstellar medium. Only a few new stars can be created out of the material that is left and the star formation rate is very low. Hence, the population of stars in S0 galaxies consists mainly of aging stars, very similar to the star population in elliptical galaxies.
As S0 galaxies have only ill-defined spiral arms they are easily mistaken for elliptical galaxies if they are seen inclined face-on or edge-on as IC 335 here. And indeed, despite the morphological differences between S0 and elliptical class galaxies, they share some common characteristics, like typical sizes and spectral features.
Both classes are also deemed “early-type” galaxies, because they are evolving passively. However, while elliptical galaxies may be passively evolving when we observe them, they have usually had violent interactions with other galaxies in their past.  In contrast,  S0 galaxies are either aging and fading spiral galaxies, which never had any interactions with other galaxies, or they are the aging result of a single merger between two spiral galaxies in the past. The exact nature of these galaxies is still a matter of debate.
European Space Agency
Credit: ESA/Hubble and NASA via NASA http://www.nasa.gov/content/goddard/hubble-sees-the-beautiful-side-of-ic-335

This image of an area on the surface of Mars, approximately 1.5 by 3 kilometers in size, shows frosted gullies on a south-facing slope within a crater.
At this time of year, only south-facing slopes retain the frost, while the north-facing slopes have melted. Gullies are not the only active geologic process going on here. A small crater is visible at the bottom of the slope.
The image was acquired on Nov. 30, 2014, by the High Resolution Imaging Science Experiment (HiRISE) camera, one of six instruments on NASA’s Mars Reconnaissance Orbiter. The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colorado. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA’s Science Mission Directorate, Washington.
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Image Credit: NASA/JPL-Caltech/University of Arizona
Caption: Livio Tornabene, Ryan Hopkins, Kayle Hansen and Eric Pilles via NASA http://www.nasa.gov/content/frosty-slopes-on-mars

The sun emitted a significant solar flare, peaking at 7:28 p.m. EST on Dec. 19, 2014. NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth’s atmosphere to physically affect humans on the ground, however — when intense enough — they can disturb the atmosphere in the layer where GPS and communications signals travel. This flare is classified as an X1.8-class flare. X-class denotes the most intense flares, while the number provides more information about its strength. An X2 is twice as intense as an X1, an X3 is three times as intense, etc.
Image Credit: NASA/SDO via NASA http://www.nasa.gov/content/holiday-lights-on-the-sun-imagery-of-a-solar-flare