Tuesday, December 26, 2017

Louis Pasteur

Louis Pasteur (1822–1895) was a French chemist and microbiologist renowned for his discoveries of the principles of vaccination, microbial fermentation, and pasteurization. He reduced mortality from puerperal fever, and created the first vaccines for rabies and anthrax. His medical discoveries provided direct support for the germ theory of disease and its application in clinical medicine. Together with Ferdinand Cohn and Robert Koch, he is regarded as one of the main founders of bacteriology.

Saturday, December 23, 2017

The oldest astronomical observatory in Asia


Cheomseongdae is an astronomical observatory in Gyeongju, South Korea. It is the oldest surviving astronomical observatory in Asia. It was constructed in the 7th century in the kingdom of Silla. Cheomseongdae was designated as South Korea's 31st national treasure in 1962. Modeled on Baekje's Jeomseongdae, which now exists only in historical records, Cheomseongdae influenced the construction of a Japanese observatory in 675, and Duke Zhou's observatory in China in 723.

Friday, December 8, 2017

Io: the most volcanic body in the solar system

Io, the most volcanic body in the solar system is seen in the highest resolution obtained to date by NASA's Galileo spacecraft. The smallest features that can be discerned are 2.5 kilometers in size. There are rugged mountains several kilometers high, layered materials forming plateaus, and many irregular depressions called volcanic calderas. Several of the dark, flow-like features correspond to hot spots, and may be active lava flows. There are no landforms resembling impact craters, as the volcanism covers the surface with new deposits much more rapidly than the flux of comets and asteroids can create large impact craters. The picture is centered on the side of Io that always faces away from Jupiter; north is to the top.

Color images acquired on September 7, 1996 have been merged with higher resolution images acquired on November 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. The color is composed of data taken, at a range of 487,000 kilometers, in the near-infrared, green, and violet filters and has been enhanced to emphasize the extraordinary variations in color and brightness that characterize Io's face. The high resolution images were obtained at ranges which varied from 245,719 kilometers to 403,100 kilometers.

Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

Saturday, December 2, 2017

Airglow of the Earth's atmosphere

Panoramic shot of the VLT platform
Airglow over the VLT (Very Large Telescope) platform.

Airglow, a faint emission of light by a planetary atmosphere, is caused by various processes in the upper atmosphere, such as the recombination of atoms which were photoionized by the sun during the day, luminescence caused by cosmic rays striking the upper atmosphere, and chemiluminescence caused mainly by oxygen and nitrogen reacting with hydroxyl ions at heights of a few hundred kilometres. It is not noticeable during the daytime because of the scattered light from the sun. The airglow at night may be bright enough to be noticed by an observer and is generally bluish in colour.

Friday, December 1, 2017

Beringian wolfs from the last Ice Age

Beringian wolves diorama

The Beringian wolf lived during the last Ice Age in northern Wyoming, the Yukon and Alaska. The wolf was robust, with strong jaws and teeth. The unique adaptation of the skull and dentition of the Beringian wolf allowed it to produce relatively large bite forces, grapple with large struggling prey, and therefore to predate and scavenge on Pleistocene megafauna. The wolf has been comprehensively studied, yielding new information on the prey species and feeding behavior of prehistoric wolves. The Beringian wolf preyed most often on horse and steppe bison, and also on caribou, mammoth, and woodland musk ox. The species survived well into the Holocene before its extinction at the close of the Ice Age, when cold and dry conditions abated and much of its prey also went extinct. The remains of ancient wolves with similar skulls and dentition have been found in north-east Siberia.