APOD 4.4 Discovery Departs

Discovery Departs

Climbing into cloudy skies, the Space Shuttle Orbiter Discovery (OV-103) took off from Kennedy Space Center Tuesday at 7 am local time. This time, its final departure from KSC, it rode atop a modified Boeing 747 Shuttle Carrier Aircraft. Following a farewell flyover of the Space Coast, Goddard Space Flight Center, and Washington DC, Discovery headed for Dulles International Airport in Virginia, destined to reside at the Smithsonian's National Air and Space Museum Udvar-Hazy Center. Discovery retires as NASA's most traveled shuttle orbiter, covering more than 148 million miles in 39 missions that included the delivery of the Hubble Space Telescope to orbit. Operational from 1984 through 2011, Discovery spent a total of one year in space.

APOD 4.3 A Dust Devil on Mars

A Dust Devil on Mars

Does this look like a random wall with spraypaint on it to anyone else? It was late in the northern martian spring when the HiRISE camera onboard the Mars Reconnaissance Orbiter spied this local denizen. Tracking south and east (down and right) across the flat, dust-covered Amazonis Planitia the core of the whirling dust devil is about 30 meters in diameter. Lofting dust into the thin martian atmosphere, its plume reaches more than 800 meters above the surface. Not following the path of the dust devil, the plume is blown toward the east by a westerly breeze. Common in this region, dust devils occur as the surface is heated by the Sun, generating warm, rising air currents that begin to rotate. Tangential wind speeds of up to 110 kilometers per hour are reported for dust devils in other HiRISE images.

APOD 4.1 The Grand Canyon in Moonlight

The Grand Canyon in Moonlight

In this alluring night skyscape recorded on March 26, a young Moon stands over the distant western horizon in conjunction with brilliant planet Venus. In the foreground, the Colorado River glistens in moonlight as it winds through the Grand Canyon, seen from the canyon's southern rim at Lipan Point. Of course, the Grand Canyon is known as one of the wonders of planet Earth. Carved by the river, the enormous fissure is about 270 miles (440 kilometers) long, up to 18 miles (30 kilometers) wide and approaches 1 mile (1.6 kilometers) deep. On this date, wonders of the night sky included the compact Pleiades and V-shaped Hyades star clusters poised just above the Moon. Bright planet Jupiter is below the closer Moon/Venus pairing, near the western horizon.

APOD 4.2 Venus and the Sisters

Venus and the Sisters

Admittedly once again, I was drawn to this image for visual purposes. I like how brilliantly the planet Venus shines and in addition how it is one of those things that even amateur stargazers such as myself can easily recognize. After wandering about as far from the Sun on the sky as Venus can get, the brilliant evening star crossed paths with the Pleiades star cluster earlier this week. The beautiful conjunction was enjoyed by skygazers around the world. Taken on April 2, this celestial group photo captures the view from Portal, Arizona, USA. Also known as the Seven Sisters, even the brighter naked-eye Pleiades stars are seen to be much fainter than Venus. And while Venus and the sisters do look star-crossed, their spiky appearance is the diffraction pattern caused by multiple leaves in the aperture of the telephoto lens. The last similar conjunction of Venus and Pleiades occurred nearly 8 years ago. As it did then, Venus will again move on to cross paths with the disk of the Sun in June.

Alvan G. Clark Biography

Macauley Cleary

Pd. 3, Astronomy

Percival

2 Mar 2012

Alvan G. Clark

Alvan G. Clark is a little-mentioned astronomer from the 1800s whose life accomplishments may be few in number, but are great in importance. While much of Clark’s accomplishments are because of his father’s work in the field of telescope making, he did take things to a new level, so to speak, innovation-wise. As far as a background goes Clark was born in Fall River, Massachusetts in 1832 and took his time rising to recognition in the field of American astronomy. He is most noted for his discovery of Sirius B and the refracting telescope with which he discovered it.

            From the moment on July 10 in 1832 when Alvan G. Clark was born he was inadvertently being set up at every turn for a life in the field of astronomy. His father was a lens maker who turned to telescope making and was known for his impeccable work. Through this opportunity Clark was able to become an optician and also take up a career in the line of lens making work. By following in his father’s footsteps Clark lead his family to create two disks of glass that were 42 inches in diameter each to fulfill a contract they had with the University of South Carolina. Upon telling this story to a colleague Clark was overheard by a man named George Ellery Hale. Luckily enough Hale was interested in the lenses and was able to purchase them when the previous deal fell through. Hale used the lenses to create the Yerkes Observatory, still one of the largest refracting telescopes today. This achievement perfectly demonstrated both the quality of work and the capabilities of Clark at such an early date.

            After this accomplishment Clark went on to take things not one, but multiple steps further than ever before. He was in Cambridgeport, Massachusetts on January 31, 1862 testing out a new refracting telescope when he unexpectedly saw a previously unidentified object. This object turned out to be what is now known as Sirius B, a dimmer version (magnitude 8) of the star Sirius located in Canis Major. In addition to this Sirius B, now labeled, was a different kind of star. It was a white dwarf. Up until this point a white dwarf star had not been found, nor had it been studied. Clark’s accidental find opened the astronomical world up to a myriad of new possibilities regarding this recently discovered type of star. The telescope that Clark used was 18 inches in diameter, smaller than many that he helped to create but still large enough to get the job done, and was a refracting telescope. Though Clark used the telescope in Massachusetts, it now resides at the landmark Dearborn Observatory of the Northwestern University in Evanston, Illinois. Alvan G. Clark’s contributions to astronomy seem minimal but in reality were necessary and long-lived as they are still in use today.   

APOD 3.7 The Mysterious Rings of Supernova 1987A

The Mysterious Rings of Supernova 1987A  

What's causing those odd rings in supernova 1987A? Twenty five years ago, in 1987, the brightest supernova in recent history was seen in the Large Magellanic Cloud. At the center of the above picture is an object central to the remains of the violent stellar explosion. Surrounding the center are curious outer rings appearing as a flattened figure 8. Although large telescopes including the Hubble Space Telescope monitor the curious rings every few years, their origin remains a mystery. Pictured above is a Hubble image of the SN1987A remnant taken last year. Speculation into the cause of the rings includes beamed jets emanating from an otherwise hidden neutron star left over from the supernova, and the interaction of the wind from the progenitor star with gas released before the explosion.

Bio Sources

http://www.nndb.com/people/702/000167201/

http://astro.uchicago.edu/yerkes/history/1892.html