720 XTF Search Results (expand=subject;f1-subject=Concepts);f1-subject%3DConcepts Results for your query: expand=subject;f1-subject=Concepts Thu, 01 Jan 1970 12:00:00 GMT Gamma-ray penetration of materials. Gamma radiation (which includes gamma rays, X-rays, and ultraviolet radiation) cannot penetrate our atmosphere, but can travel through materials such as paper and aluminum. Only heavy metals (such as lead) and other materials like concrete can block gamma rays. Thu, 01 Jan 1970 12:00:00 GMT Air Shower Schematic. A schematic diagram of particles in an extensive air shower (EAS), approaching an array of detectors at the speed of light. Thu, 01 Jan 1970 12:00:00 GMT Auger Observatory Animation. This animation models how an extensive air shower (EAS) is detected by the Pierre Auger Cosmic Ray Observatory Engineering Array. The cosmic ray particles spread out to form a shower front. The shower front is illustrated using green dots to represent electrons and positrons, and red dots to represent muons. Yellow indicates that particles have been detected coincidentally by one of the water tank detectors. Slight differences in the detection times at the various tank positions allow scientists to determine the cosmic ray arrival direction. See the sketch of the cosmic ray creating an air shower and heading towards the detector on the previous page. Thu, 01 Jan 1970 12:00:00 GMT Transmission of radiation through the atmosphere. Only visible, radio, and some infrared radiation penetrates the atmosphere. Ultraviolet photons, X-rays, and gamma rays do not. While observations at any wavelength benefit from instruments in space, detection of celestial of ultraviolet, X-ray, and gamma-ray sources require instruments in space. The development of rockets led to our ability to place these special instruments in space. Thu, 01 Jan 1970 12:00:00 GMT Electromagnetic spectrum. Scale illustrating the order and size of the wavelengths in each band of the electromagnetic spectrum. Thu, 01 Jan 1970 12:00:00 GMT Detail from the frontispiece of Giovanni Battista Riccioli's Almagestum novum (Bologna, 1651). This image depicts the slow evolution of thought about the physics of the solar system in the mid-17th century. The shield on the left represents Copernicus's view of the Universe (1543) with the Sun at the center of the Universe and all of the planets, including the Earth moving around it. Copernicus's model was opposed by the Church which held that the Earth was the center of the Universe. The shield on the right depicts Tycho Brahe's model of the Universe (1588) which reconciles the Copernican model with the early Ptolemaic model (ca. 150) in which the Sun, Moon, planets, and stars all revolve around the Earth. Brahe's model allows that the other planets revolve around the Sun, but maintains that the Earth is the stationary center of the Universe around which the Sun, dragging all of the planets with it, as well as the Moon, revolve. Brahe's shield carries more weight (tilts the balance) in this picture because the Church, a powerful arbiter of scientific thought in the 17th century, supported Brahe's mode... Thu, 01 Jan 1970 12:00:00 GMT