Mars' largest moon, Phobos, has captured public imagination because the dominant feature on its surface (22-kilometers across) is Stickney crater (9-km across), a mega crater that spans nearly half the moon. 

The crater lends Phobos a physical resemblance to the planet-destroying Death Star in the film "Star Wars." But over the decades, understanding the formation of such a massive crater has proven elusive for researchers. For the first time, physicists at Lawrence Livermore National Lab have demonstrated how an asteroid or comet impact could have created Stickney crater without destroying Phobos completely. The research, which also debunks a theory regarding the moon's mysterious grooved terrain, was published in Geophysical Review Letters.

The nearby star Proxima Centauri hosts an Earth-sized planet (called Proxima b) in its habitable zone but the star seems nothing like our sun. It's a small, cool, red dwarf star only one-tenth as massive and one-thousandth as luminous as the sun. However, new research shows that it is sunlike in one surprising way: it has a regular cycle of starspots.

Starspots (like sunspots) are dark blotches on a star's surface where the temperature is a little cooler than the surrounding area. They are driven by magnetic fields. A star is made of ionized gases called plasma. Magnetic fields can restrict the plasma's flow and create spots. Changes to a star's magnetic field can affect the number and distribution of starspots.

The US has one of the highest rates of obesity in the world, with soda consumption identified as one of the factors. On average, Americans consumed 46 gallons of soda in 2009, giving the US one of the highest rates of per capita soda consumption of any country. A recent report estimated that soda consumption caused one-fifth of weight gain in the US between 1977 and 2007.

Although individuals often consume natural products because of their potential health benefits, a new review indicates that it is not clear whether the benefits of plant-derived compounds that mimic estrogen outweigh the possible health risks.

Phytoestrogens are compounds from plants that are similar in structure to estrogen and are found in a variety of foods, especially soy. Some women may consume phytoestrogens promoted as natural alternatives to hormone replacement therapy to help ease menopausal symptoms such as hot flushes or to protect against bone loss.

ontroversy over prostate cancer screening guidelines that discourage use of PSA tests did not significantly reduce use of the test, a five-year review of more than 275,000 visits at UT Southwestern Medical Center showed.

Revised guidelines from the United States Preventive Services Task Force in 2012 advised against PSA-based screening for prostate cancer, concluding that the potential harms of overtreatment outweighed the possible benefits of early detection. UT Southwestern cancer researchers' review of electronic medical records showed that this conclusion did not discourage the number of tests ordered, contrary to some other findings.

EAST LANSING, Mich. --- Intelligence -- and not just relentless practice -- plays a significant role in determining chess skill, indicates a comprehensive new study led by Michigan State University researchers.

The research provides some of the most conclusive evidence to date that cognitive ability is linked to skilled performance -- a hotly debated issue in psychology for decades -- and refutes theories that expertise is based solely on intensive training.