Massive stars, which terminate their evolution in a cataclysmic explosion called a type-II supernova, are the nuclear engines of galactic nucleosynthesis. Among the elemental species known to be produced in these stars, the radioisotope 60Fe stands out: This radioisotope has no natural, terrestrial production mechanisms; thus, a detection of 60Fe atoms within terrestrial reservoirs is proof for the direct deposition of supernova material within our solar system. We report, in this work, the direct detection of live 60Fe atoms in biologically produced nanocrystals of magnetite, which we selectively extracted from two Pacific Ocean sediment cores. We find that the arrival of supernova material on Earth coincides with the lower Pleistocene boundary (2.7 Ma) and that it terminates around 1.7 Ma (details).
Tuesday, 16 August 2016
Sunday, 14 February 2016
Thursday, 28 January 2016
You can browse through all of history on ChronoZoom to find data in the form of articles, images, video, sound, and other multimedia. ChronoZoom links together a wealth of information that has been curated by experts and enthusiasts to tell important stories from history. By drawing upon the latest discoveries from many different disciplines, you can visualize the temporal relationships between events, trends, and themes. Some of the disciplines that contribute information to ChronoZoom include biology, astronomy, geology, climatology, prehistory, archeology, anthropology, economics, cosmology, natural history, and population and environmental studies.
Friday, 6 November 2015
It’s always shining, always ablaze with light and energy that drive weather, biology and more. In addition to keeping life alive on Earth, the sun also sends out a constant flow of particles called the solar wind, and it occasionally erupts with giant clouds of solar material, called coronal mass ejections, or explosions of X-rays called solar flares. These events can rattle our space environment out to the very edges of our solar system. In space, NASA’s Solar Dynamics Observatory, or SDO, keeps an eye on our nearest star 24/7. SDO captures images of the sun in 10 different wavelengths, each of which helps highlight a different temperature of solar material. In this video, we experience SDO images of the sun in unprecedented detail. Presented in ultra-high definition, the video presents the dance of the ultra-hot material on our life-giving star in extraordinary detail, offering an intimate view of the grand forces of the solar system.