It is hard for most people to comprehend the immense scale of the Milky Way galaxythat is home to our Solar System. Our Sun is only one of the estimated 100 to 400 billion stars in this galaxy and this may give some indication of its size. However the truly gigantic proportions of the Milky Way were revealed in early December 2009 when the Adler Planetariumunveiled the largest ever image of the galaxy. The image was captured by the Spitzer Space Telescope which is controlled by the National Aeronautics and Space Administration (NASA). The event at the Adler Planetarium revealed that the final image created is one of the most spectacular views of outer space that has ever been seen.
The Spitzer Telescope was the final mission of NASA’s Great Observatories Project which launched a family of four observatories into space. The most famous and well known of these is probably the Hubble Telescope and the program also included the Compton Gamma-Ray Observatory and the Chandra X-Ray Observatory.
The Spitzer Telescope was launched into space in August 2003. It was originally named the Space Infrared Telescope Facility and, in accordance with NASA tradition, was renamed the Spitzer Telescope following the successful demonstration of its operational capabilities. The telescope is 0.85m in size and three science instruments were also included as part of the mission. These included an Infrared Array Camera, an Infrared Spectrograph and a Multiband Imaging Photometer.
The telescope obtains images by detecting the infrared energy which is radiated by objects in space and this required that it be cooled to near absolute zero using liquid helium. With this requirement it was expected that the functional life of the telescope would be around 5 years. After this length of time it was expected that the liquid helium would become exhausted and the science instruments would be of no further use although the telescope itself would still be operational.
The event at the Adler Planetarium in Chicago demonstrated that the mission has been a great success. The image of the Milky Way the telescope has produced is one of the most stunning views of the galaxy that has ever been seen. To produce the final image data from two of the three onboard instruments was collected and processed by teams involved in the mission. These were the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) team which used data from the Infrared Array Camera and the Multiband Imaging Photometer for Spitzer Galactic Plane Survey Legacy (MIPSGAL) team which used data from the Multiband Imaging Photometer.
The image these teams created covers a huge area and was made by stitching together an incredible 800,000 individual pictures. The resulting masterpiece is 120 feet long by 3 feet wide at the sides and the width increases to 6 feet in the centre. It is the highest-resolution and largest image of the Milky Way ever created and shows the galaxy in stunning detail. The new image is detailed enough to show clusters of stars where previous pictures had shown only a single source of light. The leaders of the two teams involved in the work attended the event to unveil the image and they also gave short presentations about the work involved in creating it.
It is considered that the image is probably the best view we will have of the Milky Way for the foreseeable future. It will assist scientists studying the galaxy and should help them in better understanding some of the processes involved in its formation. The picture is to remain as a permanent exhibit at the Adler Planetarium and a trip to see it is definitely worth doing if you visit Chicago.
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