Monday, July 18, 2022

3629 - JAMES WEBB FAR FIELD - looking back in time.

  -  3629  - JAMES  WEBB  FAR  FIELD  -    looking back in time.    July, 2022,  the world got its first glimpse of that most ancient light from the James Webb Space Telescope, the most sophisticated and ambitious deep-space viewing tool yet assembled.  It is looking at this 13 billion year old light.  


-----------  3629  -    JAMES  WEBB  FAR  FIELD  -    looking back in time.   

-  Billions of years ago, long before a swirling cloud of gas and dust coalesced to form the sun, light left the earliest stars and began a long journey through space on its way to Earth.

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-  This light has been traveling ever since, covering trillions upon trillions of miles. It hurtled by galaxies and their nascent stars, some of which were accompanied by planets. 

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-  The James Webb far field is a snapshot of deepest space yet seen.  The light from galaxies swirling around a central point.   If you held a grain of sand on the tip of your finger at arm's length, that is the part of the universe that you're seeing, just one little speck of the universe, but all they way back in time.

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-  Webb telescope is the successor to the Hubble Space Telescope, which transformed science's understanding of the vastness of the universe. One of Hubble's most famous images, the “eXtreme Deep Field“, shows flecks of light representing some 5,500 galaxies, the faintest of which enable us to look back in time 13.2 billion years.

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-  Webb can see galaxies even further back just a few hundred million years after the big bang. It intercepts light in the infrared part of the spectrum, whose wavelengths are too long to be visible to the human eye.

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-    L2 is the scientific shorthand for the second LaGrange point roughly 930,000 miles from Earth. It's one of five places where the gravitational forces of the Sun and the Earth are in balance, allowing Webb to remain a fixed distance from our planet.

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-  It took a month for the telescope to get there. Then the telescope slowly and deliberately unfolded itself over the course of two weeks.  An intricate system of latches, cables and pins released a five-layer sunshield about the size of a tennis court.

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-   Once that was in place the telescope's 18 hexagonal mirrors swung into place, creating a honeycomb-like structure 21 feet across.   Each mirror is coated in 100 nanometers of gold to enhance its ability to reflect infrared light. The mirrors were carefully aligned by focusing on a star.  Behind the star were countless flecks of light, each representing a galaxy billions of years old.

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-  Hubble, launched in 1990, has offered unprecedented insight into the cosmos during its decades of service. Its observations have helped scientists determine the age of the universe and the rate of its expansion, along with discovering black holes, obscure moons and exoplanets.

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-  Webb is exponentially more powerful. Its mirror is six times larger than Hubble's, meaning it can collect far more light and look farther back in time. It also has far greater capabilities to study infrared light.

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-  Webb wouldn't work if it were where Hubble is. The newer telescope is so much more sensitive that it would be overwhelmed by light and heat from the Earth, moon and sun. But its distance away also means that it's too far away to be repaired manually by spacewalking astronauts, as Hubble has been five times since its launch.

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-  The segmented cryogenic mirrors, the five-layer sunshield, the microshutters that capture infrared light all of it had to first be imagined and lab-tested before being manufactured for use on the telescope.

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July 17, 2022       JAMES  WEBB  FAR  FIELD  -    looking back in time.        3629                                                                                                                                        

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--------------------- ---  Monday, July 18, 2022  ---------------------------






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