Free Astronomy Magazine March-April 2023 ARABIC VERSION

monitoring, with a resolution down to a few hundred meters. However, the VIIRS data alone does not pro- vide a true picture of the extent of the skyglow, and this essentially for two reasons. The first is attributable to the fact that the instrument prefe- rably records vertically radiated light, such as that emitted by spherical outdoor lamps, by floodlights, bright outdoor spotlights, and by all other light sources not shielded upwards. The second reason is that VIIRS sen- sors are blind to wavelengths be- low 500 nanometers, the very wave- lengths that host the peak emission of LED lights (400-500 nanometers) and which, moreover, are the ones that most effectively diffuse in the lo- wer atmosphere. These wavelengths ـــﺎ ﻓـــﻲ ﻳـــﻮمﻣــﻦ ــﺐ ﺗـــﺎون ﺑﺠﻨـــﻮب إﻓﺮ ﻘ ﺎﻧــﺖﻣﺪ ﻨـــﺔ ﻛ ـــﺎمﻣﺮﻛــﺰًا ﻟﻌﻠــﻢ اﻟﻔﻠــﻚ ﻓـــﻲ اﻷ اﻟ ﻨﺼــﻒ اﻟــ ـ ﺠﻨﻮﺑﻲ ﻣـــﻦ اﻟﻜــــﺮة اﻷرﺿـــــ ﺔ أﻣــــﺎ اﻵن أﺻــــﺒﺤﺖ اﻟﻨﺠـــــﻮم اﻵن ﻻ ﻳــــﺮى ﻣﻨﻬـــﺎ إﻻ اﻟﻘﻠﻴـــﻞ . ﺎﻧــﺖﻫــــﺬﻩ ﻫـــﻲ اﻟﻤﻨﻄﻘـــﺔ اﻟﺘﺠﺎرـــﺔ اﻟﻤﺮﻛﺰــــﺔ ﺎﻟﻤﺪ ﻨـــــﺔ ﻓــــــﻲﻋـــــﺎم ٢٠١٩ ] . ـــــ ز رو / ـــــﻚ ﻣﺎ [ ﻫﺎﺗﺸ ﻨﺠﺰ ﺴﺘﻜﺸــﻒﻓــ ﻠﻢ "Lost in Light" ﻣــﻦ ﺧــﻼل اﻟﺴــﻔﺮ ــﺔ ﻣﻮاﻗـﻊ ﻣﺨﺘﻠﻔــﺔ ﻋــ ﺛﻤﺎﻧ ﻣــﻦ ﻣﻨﻄﻘــﺔ ﺳــﺎن ـ ﺧﻮﺳ ﮫ اﻟ ﺤﻀﺮ ﺔ ﻓﻲ ﺎﻟ ﻔﻮر اﻟﻤﻮت ﺎ إﻟﻰ اﻣﺘﺪاد ﻣﻘﻔﺮﺑﻮاد ، ﻇـﺎﻫﺮة اﻟﺘﻠـﻮث اﻟﻀـﻮﺋﻲ اﻟﻤﻨﺘﺸـﺮة ــﺘﻢ ﺗﺠﺎﻫﻠﻬـــﺎ ًــﺎ ﻣـــﺎ ﻏﺎﻟ ـــﺎن واﻟــ ــﻞ ﻣ ﻓــﻲ . ﻋﻨــﺪﻣﺎ ﻀــﻲء اﻟﻀـــﻮء اﻟﺼــﻨﺎﻋﻲﺳــﻤﺎء اﻟﻠﻴـــﻞ ﻓﺈﻧﻨــﺎ ﻧﻔﻘـــﺪ ﺸ ﻞ ﻣ ا ﺪ رؤ ﺔ اﻟﻨﺠﻮم واﻟ ﻮاﻛﺐ واﻟﺴﺪم وﻛﺬﻟﻚ اﻹﺣﺴﺎس ﺄﻧﻨﺎ ﺟﺰء ﻣﻦ ﻣﺠﺮة ﻛﺒ ة و ﻮن أﻛ . ــﺔ ﻌــﺮضﺳـــﺮ ﺮام ﻣـــﻮراﻟﻲ ﺛﻤﺎﻧ " ﻣﺴـــﺘﻮ ﺎت " ﻣﺨﺘﻠﻔـــﺔ ﻣــﻦ اﻟﺘﻠـــﻮث ـــﺎ وأور ﻐـــﻮن اﻟﻀـــﻮﺋﻲﻋــ ﺎﻟ ﻔﻮر و ﺴـﺘﺨﺪم ــﺔ ﺗﻘﻨ ﻣــﻊ اﻟﺘـﺄﺛ اﻟﻔﺎﺻـﻞ اﻟــﺰﻣ ــﺔ اﻟــﺪراﻣﻲ ، و ﺴــﺄل ﻋﻤــﺎ ﻧﺨﺴــﺮﻩ ﻋﻨــﺪﻣﺎ ﻻ ﻧــﺘﻤﻜﻦ ﻣــﻦ رؤ اﻟ ﻨﺠﻮم . ﺗﻔﺴ ﺑﻴﺎﻧﺎﺗﻪ ﻟﻸﻏﺮاض اﻟﻌﻠﻤﻴ ﺔ، ﻋﻼوة ﻋﲆ ذﻟﻚ ﻛﺎﻧﺖ اﻏﻠﺐ اﻟﺒﻴﺎﻧﺎت ا ﻘﺪﻣﺔ ﰲ ا ﺮاﻛـﺰ اﻟﺤﴬﻳﺔ " ) ﻣﺸﺒﻌﺔ " اﻟﻜﺜـ ﻣـﻦ اﻟﻀـﻮء ﺑﺎﻟﻨﺴﺒﺔ ﻷﺟﻬﺰة اﻻﺳﺘﺸﻌﺎر ا ﺘﻮاﺿﻌﺔ ﻟﻬﺬا اﻟﻘﻤﺮ اﻟﺼﻨﺎﻋﻲ ( وﺑﺎﻟﺘﺎﱄ ﺗﻈﻬـﺮ ﻛـﻞ ﻋـﺎم داﺋﻤًﺎ اﻟﻘﻴﻤﺔ اﻟﻘﺼﻮى اﻟﺘﻲ ﻳﻤﻜﻦ أن ﻳﺼـﻞ إﻟﻴﻬﺎ ا ﺴﺘﺸﻌ ﺮ ﺗﺤﺴـﻨﺖ اﻷ ﻣـﻮر ﰲ أواﺧـﺮ ﻋﺎم ٢٠١١ ﻣﻊ إﻃﻼق وﻛﺎﻟـﺔ ﻧﺎﺳـﺎ ﻟﻠﻘﻤـﺮ اﻟﺼ ـﻨﺎﻋﻲ ) ( ﺳ ـﻮﻣﻲ ا ﺨﺼ ـﺺ ﺣ ـﻮال ﻷ ا ﻟﻄﻘﺲ و ﺗﺪﻳﺮه اﻹدارة اﻟﻮﻃﻨﻴﺔ ﻟﻠﻤﺤﻴﻄﺎت واﻟﻐﻼف اﻟﺠﻮي وﻻ ﻳﺰال ﻗﻴﺪ اﻟﺘﺸﻐﻴﻞ . اﺣﺪ أﻷﺟﻬﺰة ا ﻮﺟﻮدة ﻋﲆ ﻣـﺘﻦ ) ﻫـﻮ ( ﺳـﻮﻣﻲ ﻣﻘﻴﺎس اﻹﺷﻌﺎع ا ﺮﺋﻲ ﻟﻠﺘﺼـﻮﻳﺮ ﺑﺎﻷﺷـﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء اﻟﻨﻬ ﺣﺰﻣﺔ ( ﻓ س) اﻟﻠﻴﻞ / ﺎر ﻳﻮﻓﺮ اﻟﺒﻴﺎﻧﺎت اﻟﺘـﻲ ﻳﻤﻜـﻦ اﺳـﺘﺨﺪاﻣﻬ ﺎ ﰲ ﻣﺮاﻗﺒﺔ اﻹﺿﺎءة اﻻﺻﻄﻨﺎﻋﻴﺔ ﺑﺪﻗﺔ ﺗﺼﻞ إﱃ ﺑﻀﻊ ﻣﺌﺎت ﻣﻦ اﻷﻣﺘـﺎر . وﻣـﻊ ذﻟـﻚ ، ﻓـﺈن ﺑﻴﺎﻧﺎت ﻓـ س ) ( وﺣـﺪﻫﺎ ﻻ ﺗﻘـﺪم ﺻـﻮرة ﺣﻘﻴﻘﻴﺔ ﺪى ﺗﻮﻫﺞ اﻟﺴﻤﺎء ، وﻫﺬا أﺳﺎﺳًـﺎ ﻟﺴﺒﺒ . ﺣﻘﻴﻘﻴﺔ ﺪى ﺗـﻮﻫﺞ اﻟﺴـﻤﺎء وﻫـﺬا أﺳﺎﺳًـﺎ ﻟﺴﺒﺒ ﻳُﻌـﺰى اﻷول إﱃ ﺣﻘﻴﻘـﺔ أن اﻟﺠﻬـﺎز ﻳ ﻔﻀﻞ أن ﻳﺴﺠﻞ اﻟﻀﻮء ا ﺸﻊ رأﺳﻴﺎً ﻣﺜﻞ ﺗﻠﻚ ا ﻨﺒﻌﺜﺔ ﻣﻦ ا ﺼﺎﺑﻴﺢ اﻟﺨﺎرﺟﻴـﺔ اﻟﻜﺮوﻳـﺔ أو أو ﻣﻦ ﺟﻤﻴﻊ ﻣﺼﺎدر اﻟﻀـﻮء اﻷﺧـﺮى ﻏـ ا ﺤﻤﻴﺔ ﻷﻋﲆ ، اﻣﺎ ا ﻟﺴـﺒﺐ اﻟﺜـﺎﻧﻲ ﻓ ﻬـﻮ أن ﻣﺴﺘﺸﻌﺮات ( ﻓ س) ﻋﻤﻴﺎء ﻋـﻦ اﻷﻃـﻮال ا ﻮﺟﻴﺔ اﻟﺘﻲ ﺗﻘﻞ ﻋﻦ ٥٠٠ ﻧـﺎﻧﻮﻣﱰ وﻫـﻲ ﻢ ﻣﺎرس أﺑﺮﻳﻞ 2023