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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
Milky Way Morphology, Laurence A. Marschall
Milky Way Morphology, Laurence A. Marschall
Physics and Astronomy Faculty Publications
From our limited perspective—living on a planet that orbits one of several hundred billion stars inside the Milky Way—the detailed structure of our home galaxy is difficult to determine. It has long been recognized by astronomers as a typical spiral galaxy, one of countless flattened pinwheels of stars seen throughout the universe. By mapping the distances to more than 2,400 stars, scientists have now created, with unprecedented precision, a three-dimensional map that shows the Milky Way has a twisted shape. [excerpt]
The Limited Reign Of Saturn's Rings, Laurence A. Marschall
The Limited Reign Of Saturn's Rings, Laurence A. Marschall
Physics and Astronomy Faculty Publications
Saturn’s rings—stretching tens of thousands of miles above its equator but no more than a few hundred yards thick—mark an ancient debris field of orbiting ice shards, the remains of a moon-sized object that strayed too close and was torn to pieces by Saturn’s intense gravitation. Astronomers have debated when the rings formed and how long they will stay in orbit. Recent observations from large, land-based telescopes and orbiting spacecraft reveal that Saturn’s rings are remarkably young and are dissipating at a rapid rate. [excerpt]
Back Half Of The Year, Ian R. Clarke
Back Half Of The Year, Ian R. Clarke
Physics and Astronomy Faculty Publications
Here we are in the back half of 2016, and the days are getting shorter. We have, as of today, lost 18 minutes since the solstice on June 20, and the speed of that change is quickening. You may wonder why it is that we have our hottest weather after our longest day is behind us. The simple answer is that it takes time for land and water masses to warm up. That’s the reason that Sept. 21 is likely to be a lot warmer than March 21, even though they have the same amount of daylight. [excerpt]
Living In The Milky Way, Ian R. Clarke
Living In The Milky Way, Ian R. Clarke
Physics and Astronomy Faculty Publications
It’s finally here. Today, June 20 at 6:34 p.m., is the the summer solstice, also known as the first day of summer and, confusingly enough, midsummer’s eve. From a scientific perspective, it marks the moment the sun reaches its northernmost point in our sky. As a result of that position, it’s the shortest night and longest day if you live north of the equator. [excerpt]
Ultraviolet Luminosity Density Of The Universe During The Epoch Of Reionization, Ketron Mitchell-Wynne, Asantha Cooray, Yan Gong, Matthew Ashby, Timothy Dolch, Henry Ferguson, Steven Finkelstein, Norman Grogin, Dale D. Kocevski, Anton Koekemoer, Joel Primack, Joseph Smidt
Ultraviolet Luminosity Density Of The Universe During The Epoch Of Reionization, Ketron Mitchell-Wynne, Asantha Cooray, Yan Gong, Matthew Ashby, Timothy Dolch, Henry Ferguson, Steven Finkelstein, Norman Grogin, Dale D. Kocevski, Anton Koekemoer, Joel Primack, Joseph Smidt
Physics and Astronomy Faculty Publications
The spatial fluctuations of the extragalactic background light trace the total emission from all stars and galaxies in the Universe. A multiwavelength study can be used to measure the integrated emission from first galaxies during reionization when the Universe was about 500 million years old. Here we report arcmin-scale spatial fluctuations in one of the deepest sky surveys with the Hubble Space Telescope in five wavebands between 0.6 and 1.6 μm. We model-fit the angular power spectra of intensity fluctuation measurements to find the ultraviolet luminosity density of galaxies at redshifts greater than 8 to be log ρUV = …
A Desktop Universe For The Introductory Astronomy Laboratory, Laurence A. Marschall, Glenn A. Snyder, Paul Richard Cooper
A Desktop Universe For The Introductory Astronomy Laboratory, Laurence A. Marschall, Glenn A. Snyder, Paul Richard Cooper
Physics and Astronomy Faculty Publications
What is a well-intentioned astronomy instructor to do? There is no argument that experience with the real world is desirable in any astronomy course, especially the introductory classes that fulfill the science distribution requirements at many colleges and universities. Though it is a simple matter to take students out of doors, show them the motions of the Sun, Moon, and stars, and have them squint for a few seconds at Saturn's rings through a telescope, these activities represent only a small portion of the subject matter of modern astronomy. It is simply not possible, given the constraints of time, weather, …
The Measurement Of Astronomical Parallaxes With Ccd Imaging Cameras On Small Telescopes, Stephen J. Ratcliff, Thomas J. Balonek, Laurence A. Marschall, David L. Dupuy, Carlton R. Pennypacker, Ritu Verma, Anastasia Alexov, Vivian Bonney
The Measurement Of Astronomical Parallaxes With Ccd Imaging Cameras On Small Telescopes, Stephen J. Ratcliff, Thomas J. Balonek, Laurence A. Marschall, David L. Dupuy, Carlton R. Pennypacker, Ritu Verma, Anastasia Alexov, Vivian Bonney
Physics and Astronomy Faculty Publications
Small telescopes equipped with charge-coupled device (CCD) imaging cameras are well suited to introductory laboratory exercises in positional astronomy (astrometry). An elegant example is the determination of the parallax of extraterrestrial objects, such as asteroids. For laboratory exercises suitable for introductory students, the astronomical hardware needs are relatively modest, and under the best circumstances, the analysis requires little more than arithmetic and a microcomputer with image display capabilities. Results from the first such coordinated parallax observations of asteroids ever made are presented. In addition, procedures for several related experiments, involving single-site observations and/or parallaxes of earth-orbiting artificial satellites, are outlined.