تصاویر دیدنی

City Lights Redux

A southerly looking night view of the upper two-thirds of the Florida peninsula was recorded by the Expedition 26 crew aboard the International Space Station on Dec. 28, 2010. Cape Canaveral and the Kennedy Space Center are very well lighted on the Atlantic Ocean side of the peninsula to the left in this image. The Tampa-St. Petersburg area is seen on the Gulf of Mexico or right side of the frame. At bottom or in the north areas of the picture are portions of the state’s panhandle as well as cities and communities in southern Georgia
......................................................................................................................................

City Lights

This striking photograph features two of China’s most populous cities--Beijing and Tianjin--both located in the northern part of the country near the Bohai Gulf. The United Nations estimated 2010 population for the Beijing metropolitan area is approximately 12 million, with the population of the Tianjin metropolitan area estimated to be over 7 million.

Taken at night time by the Expedition 26 crew, the image dramatically illustrates the extent of both metropolitan areas. The smaller city of Langfang, located midway between Beijing and Tianjin, also is clearly visible, as are several other smaller developed areas to the northeast. The dark regions surrounding the well-lit urban areas are mainly agricultural fields, with wheat and corn being the major crops. Beijing is one of the recognized ancient capital cities--and the current capital--of the People’s Republic of China. The regular grid pattern of the city is clearly visible at lower upper right; concentric rings of major roadways around the city center have been added as the metropolitan area has expanded. Tianjin is a major trade center with connection to seaports on the Bohai Gulf. The city was established following the integration of the Grand Canal of China, a major artificial waterway extending from Beijing southwards to Hangzhou.
........................................................................................................................................

Decorating the Sky

This mosaic image taken by NASA's Wide-field Infrared Survey Explorer, or WISE, features three nebulae that are part of the giant Orion Molecular Cloud--the Flame nebula, the Horsehead nebula and NGC 2023.

Despite its name, there is no fire roaring in the Flame nebula. What makes this nebula shine is the bright blue star seen to the right of the central cloud. This star, Alnitak, is the easternmost star in Orion's belt. Wind and radiation from Alnitak blasts away electrons from the gas in the Flame nebula, causing it to become ionized and glow in visible light. The infrared glow seen by WISE is from dust warmed by Alnitak's radiation.

The famous Horsehead nebula appears in this image as a faint bump on the lower right side of the vertical dust ridge. In visible light, this nebula is easily recognizable as a dramatic silhouette in the shape of a horse's head. It is classified as a dark nebula because the dense cloud blocks out the visible light of the glowing gas behind it. WISE's infrared detectors can peer into the cloud to see the glow of the dust itself.

A third nebula, NGC 2023, can be seen as a bright circle in the lower half of the image. NGC 2023 is classified as a reflection nebula, meaning that the dust is reflecting the visible light of nearby stars. But here WISE sees the infrared glow of the warmed dust itself.

Color in this image represents specific infrared wavelengths. Blue represents light emitted at 3.4-micron wavelengths, mainly from hot stars. Relatively cooler objects, such as the dust of the nebulae, appear green and red. Green represents 4.6-micron light and red represents 12-micron light. This image was made from data collected after WISE began to run out of its supply of solid hydrogen cryogen in August 2010. Cryogen is a coolant used to make infrared detectors more sensitive. WISE mapped the entire sky by July using four infrared detectors, but during the period from August to October 2010, while the cryogen was depleting, WISE had only three detectors operational, and the 12-micron detector was less sensitive. This turned out to be a good thing in the case of this image, because the less-sensitive detector reduced the glare of the Flame portion of the nebula enough to bring out details of the rest of the nebula.
........................................................................................................................................

Reflections

In this image from Friday, Dec. 17, space shuttle Discovery sat on Launch Pad 39A at NASA's Kennedy Space Center in Florida, as its external fuel tank was filled with more than 535,000 gallons of super-cold liquid hydrogen and liquid oxygen during a tanking test. Data from the ship's 89 sensors were evaluated after the tank returned to ambient temperature. This morning, Discovery arrived at the Vehicle Assembly Building, completing the 3.4 mile trek from Launch Pad 39A, known as a rollback, that began at 10:48 p.m. EST on Tuesday, Dec. 21, 2010.

There, technicians will take x-ray scans beneath the foam insulation of all 108 support beams, called stringers, on Discovery’s external fuel tank. They’ll also remove sensors on the external tank from last Friday’s tanking test and reapply foam to those areas.
.......................................................................................................................................

Discovery and the Lunar Eclipse

Space shuttle Discovery waits to roll back from Launch Pad 39A to the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida in the early morning hours of Dec 21, 2010, with the beginning of the total lunar eclipse clearly in view.

Once inside the VAB, Discovery's external fuel tank will be examined and foam reapplied where 89 sensors were installed on the tank's aluminum skin for an instrumented tanking test on Dec. 17. The sensors were used to measure changes in the tank as super-cold propellants were pumped in and drained out. Data and analysis from the test will be used to determine what caused the tops of two, 21-foot-long support beams, called stringers, on the outside of the intertank to crack during fueling on Nov. 5. Discovery's next launch opportunity is no earlier than Feb. 3, 2011.
........................................................................................................................................