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.
Astronomy Picture of the Day (APOD) began on June 16, 1995 with the computer generated image shown here of Earth as a hypothetical neutron star. Each day since, the two astronomers who create APOD have devised a learn node: a webpage that focuses on a small subject interfaced by an image, and that links out into the Internet to related topics. Pushing, as learnodes.com does, for something called “learn nodes” is not an effort to invent something new. A learn node captures content for learning by exploiting the natural powers of the open Internet. The robust, 13-year history of APOD illustrates the validity and educational power of basing learning content in nodes.
Using the network node is the first key to the effectiveness in creating superior knowledge content in the open Internet. The second key is the creation of the nodes by people who are experts in their subject. The About page of APOD explains:
Astronomy Picture of the Day (APOD) is originated, written, coordinated, and edited since 1995 by Robert Nemiroff and Jerry Bonnell. The APOD archive contains the largest collection of annotated astronomical images on the internet.
In real life, Bob and Jerry are two professional astronomers who spend most of their time researching the universe. Bob is a professor at Michigan Technological University in Houghton, Michigan, USA, while Jerry is a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland USA.
Phoenix Mars Lander is the topic of a magnificent learn node in the New York Science times today. Like any quality learn node, this one in the Times focuses on a small hunk of a subject: the scheduled landing of the vehicle this week on Mars. The node has internal links to superb supporting materials such as the graphic from which a piece is shown at the top of this post – although the graphic regretfully does not have a url of its own. Other internal links do, such as the slide show.
The node aspects are stunted here because there are not links beyond the NY Times to related material, such as The University of Arizona’’s Phoenix Mars Mission home webpage and NASA’s Phoenix Mars Lander homepage. The great news is that the New York Times no longer posts its science materials for free and then a few days later closes them behind a paid subscription. Since it will remain open online, this Phoenix Mars Lander node will remain available to link into other networks of space exploration and related subjects.
This learn node focus: To keep up with what is known about our home in the cosmos, the Milky Way Galaxy, online knowledge clusters provide authoritative, up-to-date information and images. The images above are from Sloan Digital Survey, and collaboration of cluster of over 150 scientists and 25 institutions. A December 2007 SDSS news release describes the discovery that The Milky Way has a double halo, as illustrated in the drawing on the left side above. The image on the right of the theoretical model galaxy is from a January 2008 announcement of continuing SDSS surveys studying dark energy, the Milky Way galaxy and giant planets.
There are many excellent Milky Way nodes of knowledge in the open Internet. Galaxy Map, a Web site that is the work of a single expert, has a node on Our Home Galaxy with rich details. Astronomy Picture of the Day has many Milky Way images, including, for example, on on The Milky Way Near the Southern Cross.
And how do we know we live in something called a galaxy and where did our home get its name? Rice University’s Galileo Project explains:
Galileo thought that what had previously been seen as a milky luster in the sky was no more than than these invisible stars. The Milky Way then was just the view of these far distant stars from earth. Nebulae or nebulous stars were in fact actually a number of small stars clustered together. Galileo went on to prove this assertion by sketching out two “nebulae” which were indeed clusters of stars.
This learn node points to a video lecture from Yale online: Discovering Exoplanets: Hot Jupiters. In the image above the shadow is from the hand of Yale Professor Charles Bailyn, Director of Undergraduate Studies in the Department of Astronomy who delivers this and other lecture videos that are part of the Yale University open courseware for the course: Frontiers and Controversies in Astrophysics (Spring 2007). The course description says that:
Professor Bailyn explains how the outlook of our Solar System can predict what other star systems may look like. It is demonstrated how momentum equations are applied in astronomers’ search for exoplanets. Planet velocities are discussed and compared in relation to a planet’s mass. Finally, the Doppler shift is introduced and students learn how it is used to measure the velocity of distant objects, such as galaxies and planets.
Astrophysicists are discovering new extrasolar planets—those outside our Solar System—almost daily. NASA’s Spitzer Space Telescope (originally called SIRTF, or the Space Infrared Telescope Facility) and AMNH’s Lyot Project Coronograph are two of the many technologies uncovering the attributes and evolution of these faraway worlds. The techniques employed by these instruments may one day help answer one of astronomy’s reigning mysteries: do any extrasolar planets host life?
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.
