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Clarksville Civil War Roundtable’s next meeting is May 17th, 2017

 

Clarksville Civil War RoundtableClarksville, TN – The next meeting of the Clarksville (TN) Civil War Roundtable will be on Wednesday, May 17th, 2017 at the Bone & Joint Center, 980 Professional Park Drive, right across the street from Tennova Heathcare. This is just off Dunlop Lane and Holiday Drive and only a few minutes east of Governor’s Square mall.

The meeting begins at 7:00 pm and is always open to the public. Members please bring a friend or two – new recruits are always welcomed.

Topic – “Forrest’s Railroad Raid of 1864”

Nathan Bedford Forrest

Nathan Bedford Forrest

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NASA Observatories used to create detailed image of Crab Nebula

 

Space Telescope Science Institute

NASA - National Aeronautics and Space AdministrationBaltimore, MD – Astronomers have produced a highly detailed image of the Crab Nebula, by combining data from telescopes spanning nearly the entire breadth of the electromagnetic spectrum, from radio waves seen by the Karl G. Jansky Very Large Array (VLA) to the powerful X-ray glow as seen by the orbiting Chandra X-ray Observatory.

And, in between that range of wavelengths, the Hubble Space Telescope’s crisp visible-light view, and the infrared perspective of the Spitzer Space Telescope.

This image of the Crab Nebula combines data from five different telescopes. (NASA, ESA, G. Dubner (IAFE, CONICET-University of Buenos Aires) et al.; A. Loll et al.; T. Temim et al.; F. Seward et al.; VLA/NRAO/AUI/NSF; Chandra/CXC; Spitzer/JPL-Caltech; XMM-Newton/ESA; and Hubble/STScI)

This image of the Crab Nebula combines data from five different telescopes. (NASA, ESA, G. Dubner (IAFE, CONICET-University of Buenos Aires) et al.; A. Loll et al.; T. Temim et al.; F. Seward et al.; VLA/NRAO/AUI/NSF; Chandra/CXC; Spitzer/JPL-Caltech; XMM-Newton/ESA; and Hubble/STScI)

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NASA’s Dawn Spacecraft loses third reaction wheel to failure

 

Written by Elizabeth Landau
NASA’s Jet Propulsion Laboratory

NASA - National Aeronautics and Space AdministrationPasadena, CA – NASA’s Dawn spacecraft is preparing to observe Ceres on April 29th from an “opposition” position, directly between the dwarf planet’s mysterious Occator Crater and the sun. This unique geometry may yield new insights about the bright material in the center of the crater.

While preparing for this observation, one of Dawn’s two remaining reaction wheels stopped functioning on April 23rd. By electrically changing the speed at which these gyroscope-like devices spin, Dawn controls its orientation in the zero-gravity, frictionless conditions of space.

This artist's rendering shows NASA's Dawn spacecraft maneuvering above Ceres with its ion propulsion system. (NASA)

This artist’s rendering shows NASA’s Dawn spacecraft maneuvering above Ceres with its ion propulsion system. (NASA)

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NASA study suggests Dwarf Planet Ceres’ Atmosphere linked to Sun’s Behavior

 

Written by Elizabeth Landau
NASA’s Jet Propulsion Laboratory

NASA - National Aeronautics and Space AdministrationPasadena, CA – Scientists have long thought that Ceres may have a very weak, transient atmosphere, but mysteries lingered about its origin and why it’s not always present. Now, researchers suggest that this temporary atmosphere appears to be related to the behavior of the sun, rather than Ceres’ proximity to the sun.

The study was conducted by scientists from NASA’s Dawn mission and others who previously identified water vapor at Ceres using other observatories.

NASA's Dawn spacecraft determined the hydrogen content of the upper yard, or meter, of Ceres' surface. Blue indicates where hydrogen content is higher, near the poles, while red indicates lower content at lower latitudes. Vesta on the left, Ceres on the right. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI)

NASA’s Dawn spacecraft determined the hydrogen content of the upper yard, or meter, of Ceres’ surface. Blue indicates where hydrogen content is higher, near the poles, while red indicates lower content at lower latitudes. Vesta on the left, Ceres on the right. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI)

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NASA’s Juno Spacecraft makes Fifth Flyby of Jupiter

 

Written by DC Agle
NASA’s Jet Propulsion Laboratory

NASA - National Aeronautics and Space AdministrationPasadena, CA – NASA’s Juno mission accomplished a close flyby of Jupiter on Monday, March 27th, successfully completing its fourth science orbit.

All of Juno’s science instruments and the spacecraft’s JunoCam were operating during the flyby, collecting data that is now being returned to Earth. Juno’s next close flyby of Jupiter will occur on May 19th, 2017.

NASA’s Juno spacecraft made its fifth flyby over Jupiter’s mysterious cloud tops on Monday, March 27th, at 1:52am PDT (4:52am EDT, 8:52 UTC).

This enhanced-color image of a mysterious dark spot on Jupiter seems to reveal a Jovian "galaxy" of swirling storms. (NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko)

This enhanced-color image of a mysterious dark spot on Jupiter seems to reveal a Jovian “galaxy” of swirling storms. (NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko)

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NASA’s Dawn mission reveals Ceres’ Ice in Shadowed Craters related to dwarf planet’s tilt

 

Written by Elizabeth Landau
NASA’s Jet Propulsion Laboratory

NASA - National Aeronautics and Space AdministrationPasadena, CA – Dwarf planet Ceres may be hundreds of millions of miles from Jupiter, and even farther from Saturn, but the tremendous influence of gravity from these gas giants has an appreciable effect on Ceres’ orientation.

In a new study, researchers from NASA’s Dawn mission calculate that the axial tilt of Ceres — the angle at which it spins as it journeys around the sun — varies widely over the course of about 24,500 years. Astronomers consider this to be a surprisingly short period of time for such dramatic deviations.

This animation shows how the illumination of Ceres' northern hemisphere varies with the dwarf planet's axial tilt, or obliquity. Shadowed regions are highlighted for tilts of 2 degrees, 12 degrees and 20 degrees. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

This animation shows how the illumination of Ceres’ northern hemisphere varies with the dwarf planet’s axial tilt, or obliquity. Shadowed regions are highlighted for tilts of 2 degrees, 12 degrees and 20 degrees. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

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NASA’s Dawn spacecraft data used to determine age of Bright Spot on Dwarf Planet Ceres

 

Written by Elizabeth Landau
NASA’s Jet Propulsion Laboratory

NASA - National Aeronautics and Space AdministrationPasadena, CA – The bright central area of Ceres’ Occator Crater, known as Cerealia Facula, is approximately 30 million years younger than the crater in which it lies, according to a new study in the Astronomical Journal. Scientists used data from NASA’s Dawn spacecraft to analyze Occator’s central dome in detail, concluding that this intriguing bright feature on the dwarf planet is only about 4 million years old — quite recent in terms of geological history.

Researchers led by Andreas Nathues at the Max Planck Institute for Solar System Research (MPS) in Gottingen, Germany, analyzed data from two instruments on board NASA’s Dawn spacecraft: the framing camera, and the visible and infrared mapping spectrometer.

The bright spots in the center of Occator Crater on Ceres are shown in enhanced color in this view from NASA's Dawn spacecraft. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI/LPI)

The bright spots in the center of Occator Crater on Ceres are shown in enhanced color in this view from NASA’s Dawn spacecraft. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI/LPI)

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NASA takes a look back at Supernova 1987a

 

Written by Rob Gutro
NASA’s Goddard Space Flight Center

NASA - National Aeronautics and Space AdministrationGreenbelt, MD – Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following its discovery on February 23rd, 1987.

Since that first sighting, SN 1987A has continued to fascinate astronomers with its spectacular light show. Located in the nearby Large Magellanic Cloud, it is the nearest supernova explosion observed in hundreds of years and the best opportunity yet for astronomers to study the phases before, during, and after the death of a star.

This Hubble Space Telescope image shows Supernova 1987A within the Large Magellanic Cloud, a neighboring galaxy to our Milky Way. (NASA, ESA, R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and M. Mutchler and R. Avila (STScI))

This Hubble Space Telescope image shows Supernova 1987A within the Large Magellanic Cloud, a neighboring galaxy to our Milky Way. (NASA, ESA, R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation), and M. Mutchler and R. Avila (STScI))

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NASA’s Juno Spacecraft will continue current orbit around Jupiter

 

Written by DC Agle
NASA’s Jet Propulsion Laboratory

NASA - National Aeronautics and Space AdministrationPasadena, CA – NASA’s Juno mission to Jupiter, which has been in orbit around the gas giant since July 4, 2016, will remain in its current 53-day orbit for the remainder of the mission. This will allow Juno to accomplish its science goals, while avoiding the risk of a previously-planned engine firing that would have reduced the spacecraft’s orbital period to 14 days.

“Juno is healthy, its science instruments are fully operational, and the data and images we’ve received are nothing short of amazing,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington. “The decision to forego the burn is the right thing to do — preserving a valuable asset so that Juno can continue its exciting journey of discovery.”

NASA's Juno spacecraft soared directly over Jupiter's south pole when JunoCam acquired this image on February 2, 2017 at 6:06 a.m. PT (9:06 a.m. ET), from an altitude of about 62,800 miles (101,000 kilometers) above the cloud tops. (NASA)

NASA’s Juno spacecraft soared directly over Jupiter’s south pole when JunoCam acquired this image on February 2, 2017 at 6:06 a.m. PT (9:06 a.m. ET), from an altitude of about 62,800 miles (101,000 kilometers) above the cloud tops. (NASA)

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NASA’s Dawn Mission finds Evidence for Organic Material on Dwarf Planet Ceres

 

Written by Elizabeth Landau
NASA’s Jet Propulsion Laboratory

NASA - National Aeronautics and Space AdministrationPasadena, CA – NASA’s Dawn mission has found evidence for organic material on Ceres, a dwarf planet and the largest body in the main asteroid belt between Mars and Jupiter.

Scientists using the spacecraft’s visible and infrared mapping spectrometer (VIR) detected the material in and around a northern-hemisphere crater called Ernutet. Organic molecules are interesting to scientists because they are necessary, though not sufficient, components of life on Earth.

This enhanced color composite image, made with data from the framing camera aboard NASA's Dawn spacecraft, shows the area around Ernutet Crater. The bright red portions appear redder with respect to the rest of Ceres. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

This enhanced color composite image, made with data from the framing camera aboard NASA’s Dawn spacecraft, shows the area around Ernutet Crater. The bright red portions appear redder with respect to the rest of Ceres. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)

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