Free Astronomy Magazine March-April 2023 ARABIC VERSION

are, again, also the ones to which human eyesight is most sensitive in dark conditions. Paradoxically, if we evaluated the skyglow variations solely based on satellite data, we would discover that in recent de- cades the situation has not worse- ned at all and has, on the contrary, slightly improved. But our percep- tion on the ground is very different because the main component of sky- glow is the light that propagates more or less horizontally and is dif- fused by the humidity in the air. Today, the familiar skyglow that forms the backdrop to our urban en- vironments can reach more than 30 kilometers beyond the last function- ing lamppost. Street lighting, bill- boards, shop signs and storefronts, sports venue floodlights, signal lights, and countless other energy- wasting sources contribute to the skyglow, which can only be measured by the human eye at its full extent. In this scenario, Kybe and colleagues focused their study on the January 2011-August 2022 period, where satellite and ground-based observa- tions are most reliable and abun- dant. Just over 51,000 estimates of naked eye limiting magnitude were selected from the Globe at Night database and integrated with satel- lite data using appropriate mathe- matical procedures. The result was an overview of the variation of the skyglow in the period considered. أﻋـــــــــــﻼﻩ ، ـــــــــــﺔ ﻟﻤﺪ ﻨـــــــــــﺔ ﺻـــــــــــﻮرة ﺎﻧﻮراﻣ ﻟـــــــــــﻮس أﻧﺠﻠـــــــﻮس ﺗـــــــﻢ ﺗﺼـــــــﻮﻳﺮﻫﺎ ﻓـــــــﻲﻋـــــــﺎم ٢٠٠٧ ﻣـــــــﻦ ﻣﺮﺻـــﺪ ـــﺚ . ﻏﺮ ﻔ ﺗﻈﻬـــﺮا ﻟﻤﻨﻄﻘـــﺔ اﻟﻤﺤﺎﻃــــﺔ ﻧﻔﺴﻬﺎ ﻤﺎ ﻓﻲ اﻟﺼﻮرة أدﻧﺎﻩ و اﻟﺘﻘﻄﺖ اﻟ ﻓــﻲﻋـــﺎم ١٩٦٢ . اﻟﻨﻤـــﻮ اﻟﻬﺎﺋــﻞ ﺧـــﻼل ٤٥ ﻋﺎﻣًـــﺎ ــــــ ﻟﻤﺼـــــﺎدراﻟﻀـــــﻮء وﻣـــــﺎ ﺐ ﻋﻠـــــﻰ ذﻟـــــﻚ ﻣــــــﻦ ﺗﻮﻫﺞ اﻟﺴﻤﺎء . واﺿﺢ ﺸ ﻞ اﻧﺒﻌـــﺎث ﻣﺼـــﺎﺑﻴﺢ إل إ ) ي دي ٤٠٠ - ٥٠٠ ﻧﺎﻧﻮﻣﱰ ( واﻟﺘﻲ ﻋﻼوة ﻋﲆ ذﻟـﻚ ﻫـﻲ اﻷﻛﺜـﺮ اﻧﺘﺸﺎرًا ﰲ اﻟﻐﻼف اﻟﺠﻮي اﻟﺴﻔﲇ ﻟﻸرض ﻋﻨﺪ ﻫﺬه اﻷﻃﻮال ا ﻮﺟﻴ ﺔ ، ﻣﺮة أﺧﺮى ، ﻫﻲ أﻳﻀًـﺎ اﻷﻃﻮال ا ﻮﺟﻴﻪ اﻟﺘﻲ ﻳﻜﻮن ﺑﴫ اﻹﻧﺴﺎن أﻛﺜﺮ ﺣﺴﺎﺳـﻴﺔ ﻟﻬـﺎ ﰲ اﻟﻈـﺮوف ا ﻈﻠﻤـﺔ ، وﻣـﻦ ا ﻔﺎرﻗﺎت إذا ﻗﻤﻨﺎ ﺑﺘﻘﻴـﻴﻢ ﺗﺒﺎﻳﻨـﺎت اﻟـﻮﻫﺞ ـــــــ اﻟﺴﻤﺎوي ﺑﻨﺎءً ﻋﲆ ﺑﻴﺎﻧﺎ ت اﻷﻗﻤﺎر اﻟﺼـﻨﺎﻋﻴﺔ ﻓﻘﻂ ﻓﺴﻨﻜﺘﺸﻒ أﻧﻪ ﰲ اﻟﻌﻘـﻮد اﻷﺧـ ة ﻟـﻢ ﻳﺘﺪﻫﻮر اﻟﻮﺿﻊ ﻋﲆ اﻹﻃﻼق ﺑﻞ ﺗﺤﺴﻦ ﻗﻠﻴﻼً . ﻟﻜﻦ إدراﻛﻨﺎ ﻋـﲆ اﻷرض ﻣﺨﺘﻠـﻒ ﺗﻤﺎﻣًـﺎ ﻷن ا ﻜﻮن اﻷﺳﺎﳼ ﻟﻠﻮﻫﺞ اﻟﺴﻤﺎوي ﻫﻮ اﻟﻀـﻮء اﻟﺬي ﻳﻨﺘﴩ أﻓﻘﻴًﺎ ﺑﻔﻌﻞ اﻟﺮﻃﻮﺑـﺔ ﰲ اﻟﻬـﻮاء . اﻟﻴﻮم ﻳﻤﻜﻦ أن ﻳﺼﻞ اﻟﻮﻫﺞ اﻟﺴـﻤﺎوي اﻟـﺬي ﻳﺸﻜ ﻞ اﻟﺨﻠﻔﻴﺔ ﻟﺒﻴﺌﺎﺗﻨﺎ اﻟﺤﴬﻳﺔ إﱃ أﻛﺜﺮ ﻣﻦ ٣٠ ﻛﻴﻠﻮﻣﱰًا ﺣﻴﺚ ﺗﺴﺎﻫﻢ إﺿـﺎءة اﻟﺸـﻮارع واﻟﻠﻮﺣــﺎت اﻹﻋﻼﻧﻴــﺔ وﻋﻼﻣــﺎت ا ﺤــﻼت وواﺟﻬﺎت ا ﺤﻼت واﻷﺿﻮاء اﻟﻜﺎﺷﻔﺔ ﻟﻸﻣﺎﻛﻦ اﻟﺮﻳﺎﺿﻴﺔ وأﺿﻮاء اﻹﺷـﺎرة وﻣﺼـﺎدر أﺧـﺮى ﻛﺜ ة ﻣﻦ إﻫـﺪار اﻟﻄﺎﻗـﺔ ﰲ ﺗـﻮﻫﺞ اﻟﺴـﻤﺎء واﻟﺬي ﻻ ﻳﻤﻜﻦ ﻗﻴﺎﺳـﻪ إﻻ ﺑـﺎﻟﻌ اﻟﺒــﴩﻳﺔ ﺑﺄﻗﴡﻣـﺪى ﺿـﻤﻦ ﻫـﺬا اﻟﺴـﻴﻨﺎرﻳﻮ رﻛـﺰ ( ﻛﻴﺒﻲ ) وزﻣﻼؤه دراﺳﺘﻬﻢ ﻋـﲆ اﻟﻔـﱰ ة ﻣـﻦ ﻳﻨﺎﻳﺮ ٢٠١١ إﱃ أﻏﺴﻄﺲ ٢٠٢٢ اﻷرﺻﺎد ﺣﻴﺚ اﻷرﺿﻴﺔ واﻷﻗﻤﺎر اﻟﺼـﻨﺎﻋﻴﺔ أﻛﺜـﺮ ﻣﻮﺛﻮﻗﻴـﺔ و ﺗﻢ اﺧﺘﻴﺎر أﻛﺜﺮ ﻣﻦ ٥١ أﻟـﻒ ﺗﻘـﺪﻳﺮ ﻟﺤﺠـﻢ اﻟﻌ ا ﺠﺮدة ﻣﻦ ﻗﺎﻋﺪة ﺑﻴﺎﻧﺎت ) ﻏﻠﻮﺑـﺎل آت و ( ﻧﺎﻳﺖ دﻣﺠﻬﺎ ﻣﻊ ﺑﻴﺎﻧﺎت اﻷﻗﻤﺎر اﻟﺼـﻨﺎﻋﻴﺔ ا ﻨﺎﺳﺒﺔ و ﻛﺎﻧﺖ اﻟﻨﺘﻴﺠﺔ ﻧﻈﺮة ﻋﺎﻣﺔ ﻋﲆ ذﻟﻚ . ﻣﺎرس أﺑﺮﻳﻞ 2023