NASA astronaut Mark Vande Hei gets detailed views of his retina as part of regularly scheduled eye checks on the station. via NASA https://ift.tt/2T6zCd9
In 1716, English astronomer Edmond Halley noted, “This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent.” Of course, M13 is now less modestly recognized as the Great Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Sharp telescopic views like this one reveal the spectacular cluster’s hundreds of thousands of stars. At a distance of 25,000 light-years, the cluster stars crowd into a region 150 light-years in diameter. Approaching the cluster core upwards of 100 stars could be contained in a cube just 3 light-years on a side. For comparison, the closest star to the Sun is over 4 light-years away. The remarkable range of brightness recorded in this image follows stars into the dense cluster core. Distant background galaxies in the medium-wide field of view include NGC 6207 at the lower right. via NASA https://ift.tt/3owQi9e
Wikipedia article of the day is Battle of Rethymno. Check it out: Article-Link Summary: The Battle of Rethymno was part of the Battle of Crete, fought during World War II on the Greek island of Crete between 20 and 29 May 1941. Two Australian battalions, supported by Greek forces, defended an airstrip and the nearby town of Rethymno against a German paratrooper attack (pictured). Due to confusion and delays at the airfields in Greece, the German assault was launched without direct air support, and drops occurred over an extended period rather than simultaneously. German units dropping near Allied positions suffered very high casualties, both in the air and on the ground. More than 500 Germans were captured, including the local commander. The Germans concentrated their resources on the battle for the airfield at Maleme, 50 mi (80 km) to the west, which they won. The Allies ordered an evacuation of Crete on 27 May, but were unable to communicate this to the units at Rethymno. Faced by a superior force of Germans equipped with tanks and artillery the Australians surrendered on 29 May.