Free Astronomy Magazine September-October 2022 ARABIC VERSION

followed by a dramatic warming at its south pole. “This change was unexpected,” says Michael Roman, a postdoctoral re- search associate at the University of Leicester, UK, and lead author of the study published in The Planetary Sci- ence Journal . “Since we have been observing Neptune during its early southern summer, we expected temperatures to be slowly growing warmer, not colder.” Like Earth, Neptune experiences sea- sons as it orbits the Sun. However, a Neptune season lasts around 40 years, with one Neptune year lasting 165 Earth years. It has been summer- time in Neptune’s southern hemi- sphere since 2005, and the as- tronomers were ea-ger to see how temperatures were changing follow- ing the southern summer solstice. Astronomers looked at nearly 100 thermal-infrared images of Nep- ﻳﺘﺒﻌﻪ ارﺗﻔﺎع ﻛﺒ ﰲ درﺟـﺎت اﻟﺤـﺮارة ﰲ اﻟﻘﻄﺐ اﻟﺠﻨـﻮﺑﻲ . ﻳﻘـﻮل ﻣﺎﻳﻜـﻞ روﻣـﺎن زﻣﻴﻞ أﺑﺤﺎث ﻣﺎ ﺑﻌـﺪ اﻟـﺪﻛﺘﻮراه ﺑﺠﺎﻣﻌـﺔ ﻟﻴﺴﱰ ﺑﺎ ﻤﻠﻜﺔ ا ﺘﺤﺪة ، وا ﺆﻟﻒ اﻟـﺮﺋﻴﺲ ﻟﻠﺪراﺳﺔ ا ﻨﺸﻮرة ﰲ ﻣﺠﻠﺔ ﻋﻠﻮم اﻟﻜﻮاﻛﺐ " : ﻛﺎن ﻫﺬا اﻟﺘﻐﻴ ﻏ ﻣﺘﻮﻗـﻊ " ." ﻧﻈـﺮًا ﻷﻧﻨﺎ ﻛﻨﺎ ﻧﺮاﻗﺐ ﻧﺒﺘﻮن ﺧﻼل أواﺋﻞ اﻟﺼﻴﻒ اﻟﺠﻨﻮﺑﻲ ﻓﻘﺪ ﺗﻮﻗﻌﻨـﺎ أن ﺗﻜـﻮن درﺟـﺎت اﻟﺤﺮارة أﻛﺜﺮ دﻓﺌًﺎ وﻟـﻴﺲ أﻛﺜـﺮ ﺑـﺮودة ." ﻣﺜﻞ اﻷرض ، ﻳﺨﺘـﱪ ﻧﺒﺘـﻮن أﺑﻨـﺎء اﻟﺒﺤـﺮ أﺛﻨﺎء دوراﻧﻪ ﺣـﻮ ل اﻟﺸـﻤﺲ وﻣـﻊ ذﻟـﻚ ﻳﺴﺘﻤﺮ ﻣﻮﺳﻢ ﻧﺒﺘﻮن ﺣﻮاﱄ ٤٠ ﻋﺎﻣًﺎ ، ﻣﻊ ﻋﺎم واﺣﺪ ﻣﻦ ﻧﺒﺘـﻮن ﻳﺴـﺘﻤﺮ ١٦٥ ﻋﺎﻣًـﺎ أرﺿﻴًﺎ . ﻟﻘﺪ ﻛﺎن ﻓﺼﻞ اﻟﺼـﻴﻒ ﰲ ﻧﺼـﻒ اﻟﻜﺮة اﻟﺠﻨـﻮﺑﻲ ﻟﻨﺒﺘـﻮن ﻣﻨـﺬ ﻋـﺎم ٢٠٠٥ وﻛﺎن اﻟﻔﻠﻜﻴﻮن ﺣﺮﻳﺼ ﻋﲆ ﻣﻌﺮﻓﺔ ﻛﻴﻒ ﻛﺎﻧﺖ درﺟﺎت اﻟﺤﺮارة ﺗﺘﻐ ﺑﻌﺪ اﻻﻧﻘـﻼب اﻟﺼﻴﻔﻲ اﻟﺠﻨﻮﺑﻲ . درس ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﻣـﺎ ﻳﻘﺮب ﻣﻦ ١٠٠ ﺻﻮرة ﺣﺮارﻳـﺔ ﺑﺎﻷﺷـﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ﻟﻨﺒﺘﻮن ﺗﻢ اﻟﺘﻘﺎﻃﻬـﺎ ﻋـﲆ ﻣﺪى ١٧ ﻋﺎﻣًﺎ ﻟﺘﺠﻤﻴﻊ اﻻﺗﺠﺎﻫﺎت اﻟﻌﺎﻣﺔ ﰲ درﺟﺔ ﺣﺮارة اﻟﻜﻮﻛـﺐ ﺑﺘﻔﺎﺻـﻴﻞ ﻏـ ﻣﺴﺒﻮﻗﺔ ﻟﻜﻮﻛﺐ ﻧﺒﺘﻮن ، ﺗﻢ اﻟﺘﻘﺎﻃﻬﺎ ﻋﲆ ـــــــــــــــــــــــــــــــــــ ﻣﺪى ١٧ ﻋﺎﻣًﺎ ﻟﺘﺠﻤﻴﻊ اﻻﺗﺠﺎﻫﺎت اﻟﻌﺎﻣﺔ ﰲ درﺟﺔ ﺣﺮارة اﻟﻜﻮﻛـﺐ ﺑﺘﻔﺎﺻـﻴﻞ أﻛـﱪ وأﻛﺜﺮ دﻗﻪ ﻣﻦ أي وﻗﺖ ﻣﴣ . أﻇﻬﺮت ﻫﺬه اﻟﺒﻴﺎﻧﺎت أﻧﻪ ﻋﲆ اﻟﺮﻏﻢ ﻣﻦ ﺑﺪاﻳﺔ اﻟﺼـﻴﻒ اﻟﺠﻨﻮﺑﻲ ﻓﺈن ﻣﻌﻈـﻢ اﻟﻜﻮﻛـﺐ ﻗـﺪ ﺑـﺮد ﺗ ﺪرﻳﺠﻴًﺎ ﺧـﻼل اﻟﻌﻘـﺪﻳﻦ ا ﺎﺿـﻴ . ﻟﻘـﺪ اﻧﺨﻔﺾ ﻣﺘﻮﺳﻂ درﺟﺔ اﻟﺤـﺮارة اﻟﻌﺎ ﻴـﺔ ﻟﻜﻮﻛﺐ ﻧﺒﺘﻮن ﺑﻤﻘـﺪار وﺻـﻞ ٨ درﺟـﺎت ﻣﺌﻮﻳﺔ وذﻟﻚ ﰲ اﻟﻔﱰة ﺑ ﻋـﺎﻣﻲ ٢٠٠٣ و ٢٠١٨ ﻓـﻮﺟﺊ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ﺑﻌـﺪ ذﻟـﻚ ﺑﺎﻛﺘﺸﺎف ارﺗﻔﺎع ﻛﺒـ ﰲ درﺟـﺔ ﺣـﺮارة اﻟﻘﻄﺐ اﻟﺠﻨﻮﺑﻲ ﻟﻨﺒﺘـﻮن ﺧـﻼل اﻟﻌـﺎﻣ اﻷﺧ ﻳﻦ ﻣﻦ ﻣﻼﺣﻈﺎﺗﻬ ﻢ ، ﻋﻨﺪﻣﺎ ارﺗﻔﻌﺖ درﺟﺎت اﻟﺤﺮارة ﺑﴪﻋﺔ ١١ درﺟﺔ ﻣﺌﻮﻳـﺔ ﺑ ﻋﺎﻣﻲ ٢٠١٨ و ٢٠٢٠ . ﻋﲆ اﻟﺮﻏﻢ ﻣـﻦ أن اﻟﺪواﻣــﺔ اﻟﻘﻄﺒﻴــﺔ اﻟﺪاﻓﺌــﺔ ﻟﻨﺒﺘــﻮن ﻣﻌﺮوﻓﺔ ﻣﻨﺬ ﺳﻨﻮات ﻋﺪﻳﺪة ، ﻓﺈن ﻣﺜﻞ ﻫﺬه اﻟﴪﻋﺔ اﻟﻘﻄﺒﻴﺔ ﻟ ﻼﺣﱰار ﻟـﻢ ﻳﺴـﺒﻖ ﻟـﻪ ﻣﺜﻴﻞ ﻋـﲆ ﻫـﺬا اﻟﻜﻮﻛـﺐ ، ﻳﻘـﻮل ا ﺆﻟـﻒ ا ﺸﺎرك ﺟﻠ أورﺗـﻮن ﻛﺒـ اﻟﺒـﺎﺣﺜ ﰲ ﻣﺨﺘﱪ اﻟﺪﻓﻊ اﻟﻨﻔﺎث اﻟﺘﺎﺑﻊ ﻌﻬﺪ ﻛﺎﻟﺘﻚ ﰲ اﻟﻮﻻﻳــﺎت ا ﺘﺤــﺪة " إن ﺑﻴﺎﻧﺎﺗﻨــﺎ ﺗﻘــﻮم ﺑﺘﻐﻄﻴﺔ أﻗﻞ ﻣﻦ ﻧﺼﻒ ا ﻮﺳﻢ ﻧﺒﺘـﻮن ﻋﲆ ــ ﻟﺬﻟﻚ ﻟﻢ ﻳﻜﻦ أﺣﺪ ﻳﺘﻮﻗـﻊ رؤﻳـﺔ ﺗﻐﻴـ ات ﻛﺒ ة وﴎﻳﻌﺔ ." ﻗﺎم ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﺑﻘﻴﺎس درﺟﺔ ﺣـﺮارة ﻛﻮﻛـﺐ ﻧﺒﺘـﻮن ﺑﺎﺳـﺘﺨﺪام اﻟﻜﺎﻣ ات اﻟﺤﺮارﻳﺔ اﻟﺘﻲ ﺗﻌﻤﻞ ﻋﻦ ﻃﺮﻳﻖ ﻗﻴﺎس ﺿﻮء اﻷﺷﻌﺔ ﺗﺤﺖ اﻟﺤ ﻤـﺮاء اﻟﺘـﻲ ﺗﻨﺒﻌﺚ ﻣـﻦ اﻷ ﺟـﺮام اﻟﻔﻠﻜﻴـﺔ ﻣـﻦ ، أﺟـﻞ ﺗﺤﻠﻴﻠﻬ .ﺎ ﻗﺎم اﻟﻔﺮﻳﻖ ﺑﺪﻣﺞ ﺟﻤﻴﻊ اﻟﺼـﻮر ا ﻮﺟﻮدة ﻟ ﻜﻮﻛﺐ ﻧﺒﺘﻮن اﻟﺘﻲ ﺗـﻢ ﺟﻤﻌﻬـﺎ ﻋﲆ ﻣـﺪار اﻟﻌﻘـﺪﻳﻦ ا ﺎﺿـﻴ ﺑﻮاﺳـﻄﺔ اﻟﻌﺪﻳﺪ ﻣﻦ اﻟﺘﻠﺴﻜﻮﺑﺎت اﻷرﺿﻴﺔ ﺛﻢ ﻗﺎﻣﻮا ﺑﻔﺤـﺺﺿـﻮء اﻷﺷــﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء ا ﻨﺒﻌﺚ ﻣﻦ ﻃﺒﻘﺔ اﻟﻐﻼف اﻟﺠﻮي ﻟﻨﺒﺘـﻮن اﻟﺘﻲ ﺗﺴﻤﻰ اﻟﺴﱰاﺗﻮﺳﻔ ، ﻟﻘﺪ ﺳﻤﺢ ذﻟﻚ ﻟﻠﻔﺮﻳﻖ ﺑ ﺘﻜﻮﻳﻦ ﺻﻮرة ﺷﺎﻣﻠﺔ ﻋﻦ درﺟـﺔ ﺣﺮارة ﻛﻮﻛﺐ ﻧﺒﺘﻮن وﺗﻐ اﺗﻬﺎ ﺧﻼل ﺟـﺰء ﻣﻦ اﻟ ﻓﺼـﻞ ﺼـﻴﻒ ﰲ اﻟﻨﺼـﻒ اﻟﺠﻨـﻮﺑﻲ ﻟﻠﻜﻮﻛﺐ و ، ﻧﻈﺮًا ﻷن ﻛﻮﻛـﺐ ﻧﺒﺘـﻮن ﻳﺒﻌـﺪ ﻣﺴﺎﻓﺔ ﺣﻮاﱄ ٤.٥ ﻣﻠﻴﺎر ﻛﻴﻠـﻮﻣﱰ ﺗﻘﺮﻳﺒًـﺎ ﻟـﺬﻟﻚ ﻓﻬـﻮ ﺷـﺪﻳﺪ اﻟـﱪودة، ﺣﻴـﺚ ﻳﺒﻠـﻎ ﻣﺘﻮﺳﻂ درﺟﺔ ﺣﺮارة اﻟﻜﻮﻛﺐ ﺣﻮاﱄ ٢٢٠ درﺟﺔ ﻣﺌﻮﻳﺔ ﺗﺤﺖ اﻟﺼﻔﺮ ﺗﻘﺮ ﻳﺒًـﺎ ، ﻋﻠﻤـﺎً ﺑﺄن اﻟﻘﻴﺎم ﺑﻘﻴﺎس درﺟﺔ ﺣﺮارة ﻧﺒﺘﻮن ﻣﻦ اﻷرض ﻟﻴﺲ ﺑﺎ ﻬﻤﺔ اﻟﺴﻬﻠﺔ . ﻣﺠﻠﺔ Astronomy ﺎﻟﻌﺮ ﺔ ٢٩ ﺳﺒﺘﻤ أﻛﺘﻮﺑﺮ 2022