This is a video clip of what Ganymede looks like, based on images from NASA’s Galileo orbiter. The US Geological Survey has classified the surface of Ganymede into the types of terrain. The brown regions are those that are heavily cratered and much older than the light shaded regions that are smoother with few craters. These lighter shaded regions are believed to be formed by flooding of the surface with water coming from faults or even cryo-volcanos that have taken place over billions of years. Perhaps even tectonic processes are at work with some crustal ice sheets being forced downward by the emergence of newer icy material. Over 8 years at Jupiter Galileo spacecraft made 6 close flyby of the Ganymede and detected a magnetic field coming from the moon itself. In addition, the best models of Ganymede from the Galileo data showed a deep ocean under a thick ice crust.
February 11, 2015 marks five years in space for NASA’s Solar Dynamics Observatory, which provides incredibly detailed images of the whole sun 24 hours a day. Capturing an image more than once per second, SDO has provided an unprecedentedly clear picture of how massive explosions on the sun grow and erupt ever since its launch on Feb. 11, 2010. The imagery is also captivating, allowing one to watch the constant ballet of solar material through the sun’s atmosphere, the corona. Read the rest of this entry
The sun emitted a significant solar flare, peaking at 1:48 p.m. EDT on Sept. 10, 2014. NASA’s Solar Dynamics Observatory captured images 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.