Back to Astronomy Cafe by Sten Odenwald PDF

By Sten Odenwald

ISBN-10: 0813341663

ISBN-13: 9780813341668

How briskly does gravity shuttle? while will the solar cross nova? Who invented the sunshine 12 months? can we ever trip to the celebs? those are only a few of the strange and renowned questions NASA astronomer Sten Odenwald solutions in again to the Astronomy Caf?, in response to his award-winning web site "for the astronomically disadvantaged." because his acclaimed past booklet The Astronomy Caf? released in 1998, the distance neighborhood has been became on its head with totally new discoveries: ion propulsion, darkish subject, gravity and magnetic reversals, the Cosmic darkish a while, and over a hundred new planets. within the all-new again to the Astronomy Caf?, Odenwald solutions the most recent and most-asked questions when it comes to those fresh discoveries. His hugely own and authoritative sort makes figuring out the cosmos much less intimidating, interesting, and fun.Since he opened his site "The Astronomy Caf?" in 1995, Odenwald has replied over 50,000 e-mailed questions. His person solutions were downloaded over 7.5 million occasions, making him the main sought-after "answer guy" for astronomy in human heritage.

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The length of day or LOD is monitored by using trans-Atlantic Very Long Base Line Interferometry, a technique pioneered and still used by astronomers to study distant quasars. During the 1982-1983 El Nino, an even stronger LOD increase of 800 microseconds was detected, with a milder LOD increase detected a year later of about 400 microseconds. To understand how air currents can affect Earth's rotation, you have to consider an ice skater on the ice doing a spin. If she changes how far out she holds her hands by just a little, the rapidity of her spin is affected.

General relativity says that the universe is a four-dimensional object and that gravity can only be described in its full four-dimensional terms. This is hard for us to do because we keep wanting to think of things happening in space at separate times. We insist on slicing gravity's field one time step at a time. At each time step, the volume of space increases, but in some sense, this space, like the pulp of the watermelon, has always been there. In each slice, the space does not "come" from anywhere, it is just revealed to us a moment at a time like the pulp in the slices of the watermelon.

In 2002, a team of scientists at Harvard University made an even more exciting, and controversial, discovery. Adam Dziewonski and graduate student Miaki Ishii studied 325,000 seismic waves that had passed directly through the center of Earth in the last 30 years. About 3,000 of these seismic events show a pronounced change as they penetrate even closer to the center. Their best model accounting for the velocity changes within the inner core is that there is a separate, 360-mile diameter, mini-planet in its center.

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Back to Astronomy Cafe by Sten Odenwald


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