These observations, taken by NASA’s Solar Terrestrial Relations Observatory, or STEREO on Aug. 5, 2007, helped scientists define the outer limit of the sun’s atmosphere.

Credit: NASA/STEREO

These observations, taken by NASA’s Solar Terrestrial Relations Observatory, or STEREO on Aug. 5, 2007, helped scientists define the outer limit of the sun’s atmosphere.Credit: NASA/STEREOThe sun’s volatile atmosphere is even bigger than expected, a NASA spacecraft revealed through observations of gigantic waves.While the sun itself is 864,938 miles (1.392 million kilometers) wide, NASA’s Solar Terrestrial Relations Observatory, or STEREO, found that the solar atmosphere, known as the corona, stretches 5 million miles (8 million km) above the sun’s surface.”We’ve tracked sound-like waves through the outer corona and used these to map the atmosphere,” Craig DeForest of the Southwest Research Institute in Boulder, Colorado, said in a statement from NASA. “We can’t hear the sounds directly through the vacuum of space, but with careful analysis we can see them rippling through the corona.”via Giant Waves Reveal Surprising True Size of Sun’s Atmosphere.

A mysterious X-ray signal has been found in a detailed study of galaxy clusters using NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton. One intriguing possibility is that the X-rays are produced by the decay of sterile neutrinos, a type of particle that has been proposed as a candidate for dark matter.

While holding exciting potential, these results must be confirmed with additional data to rule out other explanations and determine whether it is plausible that dark matter has been observed.

Astronomers think dark matter constitutes 85% of the matter in the Universe, but does not emit or absorb light like “normal” matter such as protons, neutrons and electrons that make up the familiar elements observed in planets, stars, and galaxies. Because of this, scientists must use indirect methods to search for clues about dark matter.

via Mysterious X-ray Signal Intrigues Astronomers | NASA.