This learn node is about Tycho’s supernova that Brahe saw Nov. 11, 1572. As Yahoo! News reports, Brahe was astonished to see what he thought was a brilliant new star in the constellation Cassiopeia. The light eventually became as bright as Venus and could be seen for two weeks in broad daylight. After 16 months, it disappeared.
This learn node is centered in the 2008 discovery at Rensselaer Polytechnic Institute of how the dolphin kicks with huge power — something that has been a mystery called Gray’s Paradox. Six nodes emerge from the open internet in this animation, providing connected places to learn about dolphins and their power kick.
In this learn node the 2008 discovery of how the dolphin kicks with huge power is spotlighted at Rensselaer Polytechnic Institute where the discovery was made. For decades, scientists have puzzled over the sea mammal’s speed, since “Gray’s Paradox” was described, as the Rensselaer website explains:
There was something peculiar about dolphins that stumped prolific British zoologist Sir James Gray in 1936. He had observed the sea mammals swimming at a swift rate of more than 20 miles per hour, but his studies had concluded that the muscles of dolphins simply weren’t strong enough to support those kinds of speeds. The conundrum came to be known as “Gray’s Paradox.”
This learn node features a tiny dinosaur with big canine teeth that the Natural History Museum reports shows for the first time how one of the earliest dinosaurs grew into an adult. The webpage explains:
The turkey-sized reptile called Heterodontosaurus lived around 190 million years ago in the Early Jurassic period and had an unusual combination of molar-like and canine teeth.
Reptiles usually have small same-sized teeth along the length of their mouth but Heterodontosaurus had 2 fang-like canines at the front.
The image posted here is from a video narrated by Dr. Richard Butler, a dinosaur expert at the museum and featured on the page linked above.
Two contrasting behaviors: The first is steady swimming at slow and intermediate speeds using low amplitude axial undulations (i.e. the side to side displacement of the body is small). The second is burst swimming and escape responses using high amplitude axial undulation. In the escape response, a fish bends into a C-like posture then whips its tail in the opposite direction, accelerating a mass of water behind the fish, which causes the fish to accelerate forward. The key is that body bending is small in steady swimming and large in bursts and escapes. Also, the escape response can be very fast, that is less than 1/10th of a second.
Early Cambrian arthropod chain gangs this learn node describes are fossilized in chain formation that reveals community behavior. The chain gang 525-million-year-old fossils were found in southern China’s Chengjiang Lagerstatte fossil field. A Science News report of the discovery says that the discovery site is “a treasure trove of fossils often compared to Canada’s Burgess Shale.” The above image from Science News (credit Derek Siviter) shows the that newly discovered species of Early Cambrian arthropod formed sturdy chains of about 20 individuals. In the report:
“Of the millions of fossils, the chances of getting an occurrence where we can determine collective behavior is quite rare,” says coauthor Derek Siveter of the University of Oxford in England. He and his colleagues found 22 complete or partial chains, but only one solitary specimen.
Comparing the sinuses in some newly studied dinosaur bones from Argentina with bird anatomy, this learn node from the Public Library of Science lets students go online to peer over the shoulders of working scientists. The drawing is from Figure 1 in the article. In their recent work concerning the the anatomical relationships of dinosaurs and birds, the scientists here tell us:
In this paper, we describe a new large-bodied theropod from the Late Cretaceous of Argentina, Aerosteon riocoloradensis gen. et sp. nov., characterized by cranial and postcranial bones that are exceptionally pneumatic. Some of its postcranial bones show pneumatic hollowing that can be linked to intrathoracic air sacs that are directly involved in lung ventilation. As a result of an extraordinary level of pneumatization, as well as the excellent state of preservation of much of the axial column and girdles, Aerosteon helps to constrain hypotheses for the evolution of avian-style respiration.
Galileo and the Pendulum is a node for learning that is part of a rich cluster and course, The Galileo Project at Connexions. Other sections of the Galileo Project are his biography, family life, the Inquisition, and descriptions of his work on motion, mechanical devices, and the telescope.
This outstanding medical website about radiology is a learn node unto itself. There are articles richly illustrated with radiological images — X-rays — organized by anatomy. Major groups are abdomen, cardiovascular, chest, mammography, musculoskeletal, pediatrics, and neuroradiology. The Top Sites page connects to many more articles and websites, forming a cluster of nodes about radiological imaging.
Remote sensing imagery and study materials abound on the internet. An excellent cluster of information can be found at the Atmospheric Radiation Measurement (ARM) Program which “is a multi-laboratory, interagency program, and is a key contributor to national and international research efforts related to global climate change. A primary objective of the program is improved scientific understanding of the fundamental physics related to interactions between clouds and radiative feedback processes in the atmosphere. ARM focuses on obtaining continuous field measurements and providing data products that promote the advancement of climate models.”
To learn scientific and technical background for the field MIT offers open couseware on Atmospheric Radiation that is “an introduction to the physics of atmospheric radiation and remote sensing including use of computer codes. Subjects covered include: radiative transfer equation including emission and scattering, spectroscopy, Mie theory, and numerical solutions. We examine the solution of inverse problems in remote sensing of atmospheric temperature and composition.”
The illustration below shows a learn node, which you can use as an educator to make webpages more findable. The top little circles illustrate links out to content nodes related to the subject of the large circle. Bottom left, experts connect to the node affirming its quality - giving it juice. Bottom right, a student connects to the node to learn the subject of its content.
BBC reports the 2008 discovery by Max Planck Institute scientists, using telescopes in Hawaii and Spain to capture faint light echoes of the original explosion — in effect capturing a fossil imprint of Tycho’s famous supernova. Wikipedia’s excellent article on Tycho’s Supernova for more background. NASA’s dictionary defines supernova and other relevant terms. The Galileo Project has a fine biography of Tycho Brahe. MIT’s open courseware offers instruction on the Plasma Physics that is a major focus for Tycho’s supernova.
