Free Astronomy Magazine July-August 2022 ARABIC VERSION

T his diagram shows three layers of aerosols in the atmospheres of Uranus and Neptune, as modeled by a team of scientists led by Patrick Irwin. The height scale on the diagram represents the pressure above 10 bar. The deepest layer (the Aerosol-1 layer) is thick and composed of a mix- ture of hydrogen sulfide ice and particles produced by the interaction of the planets’ atmospheres with sunlight. The key layer that affects the col- ors is the middle layer, which is a layer of haze particles (referred to in the paper as the Aerosol-2 layer) that is thicker on Uranus than on Neptune. Above both of these layers is an extended layer of haze (the Aerosol-3 layer) similar to the layer below it but more tenuous. On Neptune, large methane ice particles also form above this layer. [International Gemini Observatory/NOIRLab/NSF/AURA, J. da Silva/NASA /JPL-Caltech /B. Jónsson] that, on both planets, methane ice condenses onto the particles in this layer, pulling the particles deeper into the atmosphere in a shower of methane snow. Because Neptune has a more active, turbulent atmos- phere than Uranus does, the team believes Neptune’s atmosphere is more efficient at churning up methane particles into the haze layer and producing this snow. This removes more of the haze and keeps Neptune’s haze layer thinner than it is on Uranus, meaning the blue color of Neptune looks stronger. “We hoped that developing this model would help us understand clouds and hazes in the ice giant atmospheres,” commented Mike Wong, an astronomer at the Univer- sity of California, Berkeley, and a member of the team behind this re- sult. “Explaining the difference in color between Uranus and Neptune was an unexpected bonus!” To create this model, Irwin’s team analyzed a set of observations of the planets encompassing ultravio- let, visible, and near-infrared wave- lengths (from 0.3 to 2.5 micro- meters) taken with the Near-In- frared Integral Field Spectrometer (NIFS) on the Gemini North tele- scope near the summit of Mau- nakea in Hawai’i — which is part of the international Gemini Observa- tory, a Program of NSF’s NOIRLab — as well as archival data from the NASA Infrared Telescope Facility, also located in Hawai’i, and the NASA/ESA Hubble Space Telescope. The NIFS instrument on Gemini North was particularly important to this result as it is able to provide spectra — measurements of how bright an object is at different wavelengths — for every point in its field of view. This provided the team with detailed measurements of how reflective both planets’ at- mospheres are across both the full disk of the planet and across a range of near-infrared wave- lengths. “The Gemini observatories continue to deliver new insights into the nature of our planetary neighbors,” said Martin Still, Gem- ini Program Officer at the National Science Foundation. “In this experi- ment, Gemini North provided a com- ponent within a suite of ground- and space-based facilities critical to the detection and characterization of atmospheric hazes.” The model also helps explain the dark spots that are occasionally vis- ible on Neptune and less commonly detected on Uranus. While as- tronomers were already aware of the presence of dark spots in the at- mospheres of both planets, they didn’t know which aerosol layer was causing these dark spots or why the aerosols at those layers were less re- flective. The team’s research sheds light on these questions by showing that a darkening of the deepest layer of their model would produce dark spots similar to those seen on Nep- tune and perhaps Uranus.     ﻳﻌﺘﻘـــﺪ اﻟﻔﺮﻳـــﻖ أﻧـــﻪ ﻋـــﲆ ﻛـــﻼ اﻟﻜـــﻮﻛﺒﲔ ﻳﺘﻜﺜــــﻒ ﺟﻠﻴــــﺪ اﳌﻴﺜــــﺎن ﻋـــــﲆ اﳉﺴــــﻴﻤﺎت اﳌ ﻮﺟـــﻮدة ﻫــــﺬه اﻟﻄﺒﻘــــﺔ ﳑــــﺎ ﻳﺴــــﺤﺐ اﳉﺰﻳﺌﺎت إﱃ ﻋﻤﻖ أﻋﻤﻖ اﻟﻐﻼف اﳉﻮي ﻇﻞ ﺗﺴﺎﻗﻂ ﺛﻠﻮج اﳌﻴﺜـﺎن . ﻧﻈـﺮًا ﻷن اﻟﻐـﻼف اﳉــﻮي ﻟﻨ ﺘــﻮن أﻛــﱶ ﻧﺸــﺎ ﻃًﺎ واﺿــﻄﺮاﺑًﺎ ﻣــﻦ أوراﻧــﻮس ﻳﻌﺘﻘــﺪ اﻟﻔﺮﻳــﻖ أن اﻟﻐــﻼف اﳉــﻮي ﻟﻨ ﺘـــﻮن أﻛـــﱶ ﻛﻔـــﺎءة ﺗﺤﻮﻳـــﻞ ﺟﺰﻳﺌـــﺎت اﳌﻴﺜﺎن إﱃ ﻃﺒﻘﺔ اﻟﻀـﺒﺎب وإﻧﺘـﺎج ﻫـﺬا اﻟـﺜﻠﺞ ﻫﺬا ﻳﺰﻳـﻞ اﳌﺰﻳـﺪ ﻣـﻦ اﻟﻀـﺒﺎب وﻳﺤـﺎﻓﻆ ﻋـﲆ ﻃﺒﻘـﺔ ﺿـﺒﺎب ، ﻧﺒﺘـﻮن أرق ﳑـﺎ ﻫـﻲ ﻋﻠﻴـﻪ ﻋـﲆ أوراﻧــﻮس ، ﳑـﺎ ﻳﻌـﲏ أن اﻟﻠـﻮن اﻷزرق ﻟﻨ ﺘـﻮن ﻳﺒــﺪو أﻗــﻮى . ﻋﻠــﻖ ﻣﺎﻳــﻚ ووﻧــﻎ ﻋــﺎﱂ اﻟﻔﻠــﻚ ﺑﺠﺎﻣﻌﺔ ﻛﺎﻟﻴﻔﻮرﻧﻴﺎ ، ﺑﲑﻛﲇ ، وﻋﻀﻮ اﻟﻔﺮﻳﻖ اﳌﺴــﺌﻮل ﻋــﻦ ﻫــﺬه اﻟﻨ ﻴﺠــﺔ " : ﻛﻨــﺎ ﻧﺄﻣــﻞ أن ﻳﺴـــﺎﻋﺪﻧﺎ ﺗﻄـــﻮﻳﺮ ﻫـــﺬا اﻟﻨﻤـــﻮذج ﻓﻬـــﻢ اﻟﺴﺤﺐ واﻟﻀﺒﺎب اﻟﻐـﻼف اﳉـﻮي ﻟﻠﺠﻠﻴـﺪ اﻟﻌﻤــﻼق " ." ﻛـــﺎنﴍح اﻻﺧـــﺘﻼف اﻟﻠـــﻮن ﺑﲔ أوراﻧﻮس وﻧﺒﺘﻮن ﻣﻜﺎﻓﺄة ﻏـﲑ ﻣﺘﻮﻗﻌـﺔ "! ﻹﻧﺸــﺎء ﻫــﺬا اﻟﻨﻤــﻮذج ، ﻗــﺎم ﻓﺮﻳــﻖ إﻳــﺮوﻳﻦ ﺑﺒ ﺒ ﺒ ﺐ ﺑﺘﺤﻠﻴــﻞ ﳎﻤﻮﻋــﺔ ﻣــﻦ أرﺻــﺎد اﻟﻜﻮاﻛــﺐ اﻟــﱵ ﺗﺸـــﻤﻞ أﻃـــﻮال ﻣﻮﺟـــﺎت ﻓـــﻮق ﺑﻨﻔﺴـــﺠﻴﺔ وﻣﺮﺋﻴــﺔ وﻗﺮﻳﺒــﺔ ﻣـﻦ اﻷﺷــﻌﺔ ﺗﺤـﺖ اﳊــ اء ﻣﻦ ) ٠.٣ إﱃ ٢.٥ ﻣﻴﻜﺮوﻣﱰ ( ﻣﺄﺧﻮذة ﲟﻘﻴـﺎس ﻃﻴــﻒ اﳌﺠــﺎل اﻟﻘﺮﻳــﺐ ﻣــﻦ اﻷﺷــﻌﺔ ﺗﺤــﺖ اﳊ اء ) ﺑﺘﻠﺴﻜﻮب ﺟﻴﻤﻴﲏ اﻟﺸﻤﺎﱄ ﺑﺎﻟﻘﺮب ﻣﻦ ﻗ ﻤﺔ ﺟﺒﻞ ﻣﻮﻧﺎ ﻛﻴﺎ ﻫﺎواي وﻫﻮ ﺟـﺰء ﻣــﻦ ﻣﺮﺻــﺪ ﺟﻴﻤﻴــﲏ اﻟـــﺪوﱄ ﺑﺎﻹﺿــﺎﻓﺔ إﱃ ﺑﻴﺎﻧـــﺎت أرﺷـــﻴﻔﻴﺔ ﻣـــﻦ ﻣﻨﺸـــﺄة ﺗﻠﺴـــﻜﻮب اﻷﺷـﻌﺔ ﺗﺤـﺖ اﳊـ اء اﻟﺘـﺎﺑﻊ ﻟﻨ ﺎﺳـﺎ اﳌﻮﺟـﻮد أﻳﻀًﺎ ﻫﺎواي و ﺗﻠﺴـﻜﻮب ﻫﺎﺑـﻞ اﻟﻔﻀـﺎﰄ ﻟﻘـﺪ ﻛـﺎن ﺟﻬـﺎز ﻣﻄﻴـﺎف اﳌﺠـﺎل اﻟﻘﺮﻳـﺐ ﻣــﻦ اﻷﺷـــﻌﺔ ﺗﺤـــﺖ اﳊـــ اء ﻣﺮﺻـــﺪ ﻧـــﻮرث ﺟﻴﻤﻴﲏ ﻏﺎﻳﺔ اﻷﻫﻤﻴﺔ ﻟﻬـﺬه اﻟﻨ ﻴﺠـﺔ ﻷﻧـﻪ ﻗــﺎدر ﻋــﲆ ﺗــﻮﻓﲑ أﻃﻴــﺎف - ﻗﻴﺎﺳــﺎت ﳌــﺪى اﳉﺴﻢ ﺳﻄﻮع ﺑـﺄﻃﻮال ﻣﻮﺟﻴـ ﻪ ﳐﺘﻠﻔـﺔ ﻟﻜـﻞ ﻧﻘﻄــﺔ ﳎــﺎل رؤﻳﺘــﻪ . ﻗــﺪم ﻫــﺬا ﻟﻠﻔﺮﻳـــﻖ ﻗﻴﺎﺳﺎت ﻣﻔﺼـﻠﺔ ﻟﻜﻴﻔﻴـﺔ اﻧﻌﻜـﺎس اﻟﻐـﻼف اﳉــﻮي ﻟﻜــﻼ اﻟﻜﻮاﻛــﺐ ﻋــﱪ اﻟﻘــﺮص اﻟﻜﺎﻣــﻞ ﻟﻠﻜﻮﻛــﺐ ﻛــﺬﻟﻚ وﻋــﱪ ﳎﻤﻮﻋــﺔ ﻣــﻦ أﻃــﻮال ــــــــــــــ ﻣﻮﺟﺎت اﻷﺷﻌﺔ ﺗﺤـﺖ اﳊـ اء اﻟﻘﺮﻳﺒـﺔ . ﻗـﺎل ﻣــﺎرﺗﻦ ﺳـــ ﻴﻞ ﻣﺴــﺌﻮل ﺑﺮﻧــﺎﱅ ﺟﻴﻤﻴـــﲏ ﻣﺆﺳﺴﺔ اﻟﻌﻠﻮم اﻟﻮﻃﻨﻴـﺔ ، " ﺗﻮاﺻـﻞ ﻣﺮاﺻـﺪ ﺟﻴﻤﻴﲏ ﺗﻘﺪﱘ رؤى ﺟﺪﻳﺪة ﻟﻄﺒﻴﻌﺔ اﻟﻜﻮاﻛـﺐ اﳌﺠﺎ ورة ﻟﻨﺎ " ." ﻫـﺬه اﻟﺘﺠﺮﺑـﺔ ﻛـﺎن ﻣﺮﺻـﺪ ﺟﻴﻤﻴﲏ ﻧﻮرث ﻋﻨﴫـ أﺳـﺎﳼ ﺿـﻤﻦ ﳎﻤﻮﻋـﺔ ﻣﻦ اﳌﻨﺸﺎت اﻷرﺿﻴﺔ واﻟﻔﻀـﺎﺋﻴﺔ ﻻﻛﺘﺸـﺎ ف وﺗﻮﺻﻴﻒ اﻷﻏﻠﻔﺔ اﳉﻮﻳﺔ اﻟﻀـﺒﺎﺑﻴﺔ ". ﻳﺴـﺎﻋﺪ اﻟﻨﻤﻮذج أﻳﻀًﺎ ﺗﻔﺴﲑ اﻟﺒﻘـﻊ اﻟﺪاﻛﻨـﺔ اﻟـﱵ ﺗﻈﻬــﺮ أﺣﻴﺎﻧًــﺎ ﻋــﲆ ﻧﺒﺘــﻮن وأﻗــﻞ ﺷــﻴﻮﻋًﺎ أوراﻧـﻮس . ﺑﻴﻨﻤـﺎ ﻛـﺎن ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ ﻳـﺪرﻛﻮن ﺑﺎﻟﻔﻌـﻞ وﺟـﻮد ﺑﻘـﻊ داﻛﻨـﺔ اﻟﻐـﻼف اﳉـﻮي ﻟﻜــﻼ اﻟﻜـــﻮﻛﺒﲔ ، ﱂ ﻳﻌﺮﻓـــﻮا أي ﻃﺒﻘـــﺔ ﻣـــﻦ اﻟﻬﺒـﺎء اﳉـﻮي ﺗﺴـ ﺐ ﻫـﺬه اﻟﺒﻘـﻊ اﳌﻈﻠﻤـﺔ أو ﳌﺎذا ﻛﺎن اﻟﻬﺒﺎء اﳉﻮي ﺗﻠﻚ اﻟﻄﺒﻘـﺎت أﻗـﻞ ﻋﺎﻛﺴــﻴﻪ، ﻳﻠﻘــﻲ ﺑﺤــﺚ اﻟﻔﺮﻳــﻖ اﻟﻀــﻮء ﻋــﲆ ﻫــﺬه اﻷﺳــﺌﻠﺔ ﻣــﻦ ﺧــﻼل إﻇﻬــﺎر أن ﺗﻌﺘــﻴﻢ اﻟﻄﺒﻘــﺔ اﻷﻋﻤــﻖ ﻣــﻦ ﳕــﻮذﺟﻬﻢ ﺳــﻴﺆدي إﱃ ﻇﻬﻮر ﺑﻘﻊ داﻛﻨﺔ ﳑﺎﺛﻠـﺔ ﻟﺘﻠـﻚ اﻟـﱵ ﺷـﻮﻫﺪت ﻋﲆ ﻛﻮﻛﺐ ﻧﺒﺘﻮن ورﲟﺎ أوراﻧﻮس . ــﺎﻧﻲ ﻳﻮﺿـﺢﻫــﺬا اﻟﺮﺳـﻢ اﻟﺒ ــﻮيﻓـﻲ ــﺎء ا ﺛـﻼثﻃ ﻘــﺎتﻣـﻦ اﻟﻬ ــﻮيﻷوراﻧـﻮسوﻧ ﺘـﻮن اﻟﻐــﻼف ا ــﺎدة ﺎﺗﺮ ـﻚ إﻳــﺮوﻳﻦ ﺻــﻤﻤﮫ ﻓﺮ ـﻖﻣــﻦ اﻟﻌﻠﻤـﺎء ﻘ ﻋﻠــﻰاﻟﻨﺤــﻮ اﻟــﺬ . ـﺎساﻻر ﻔـﺎع ﻋﻠـﻰ ﻣﻘ ـﺎﻧﻲ ﻤﺜـﻞ اﻟﻀـﻐﻂﻓـﻮق اﻟﺮﺳـﻢ اﻟﺒ ١٠ ـﺎر . أﻋﻤـﻖﻃ ﻘـﺔ ) ـﺎء ﻃ ﻘــﺔ اﻟﻬ -١ ( وا ﺴـ ﻤﺎ ــﺪروﺟ ـﺪ اﻟﻬ ـﺪ ﻛ ﺘ ـﻮن ﻣــﻦﺧﻠـ ﻂﻣـﻦ ﺟﻠ ﺳـﻤ ﻜﺔ وﺗﺘ ت اﻟﻨﺎﺗﺠـﺔ ﻋـﻦ ﺗﻔﺎﻋــﻞ أﺟـﻮاء اﻟ ﻮاﻛـﺐﻣـﻊﺿــﻮء اﻟﺸﻤﺲ . ﺗﺆﺛﺮ اﻟﻄ ﻘﺔ اﻷﺳﺎﺳ ﺔ اﻟ ﻋﻠﻰاﻷﻟﻮانﻫﻲاﻟﻄ ﻘﺔ اﻟﻮﺳﻄﻰ وﻫﻲﻃ ﻘﺔ ﻣﻦﺟﺰ ﺌﺎت اﻟﻀ ﺎب ) ﺸﺎرإﻟﻴﻬﺎ ﺎﺳﻢﻃ ﻘﺔ اﻟﻬ ﺎء -٢ ( ﺗ ﻮن أﻛ ﺳﻤ ًﺎ ﻋﻠﻰأوراﻧـﻮسﻣﻨﻬـﺎ واﻟ ﻋﻠﻰﻧ ﺘﻮن ﺗﻮﺟـﺪﻃ ﻘـﺔ ﻣﻤﺘـﺪة ﻣـﻦ اﻟﻀـ ﺎب ﻓﻮق ﻠﺘﺎ اﻟﻄ ﻘﺘ ) ـﻮي ـﺎء ا ﻃ ﻘـﺔ اﻟﻬ - ٣ ( ﺗﺸـ ﮫ اﻟﻄ ﻘـﺔ اﻟﻤﻮﺟـﻮدة ﺗﺤﺘﻬـﺎ وﻟﻜﻨﻬـﺎ أﻛـ ﻫﺸﺎﺷـﺔ . ـﺪ اﻟﻤ ﺜـﺎن ﻋﻠـﻰﻧ ﺘـﻮن ، ﺗﺘﺸـ ﻞﺟﺰ ﺌـﺎتﺟﻠ اﻟﻜﺒ ة أ ﻀًﺎ ﻓﻮقﻫﺬﻩ اﻟﻄ ﻘﺔ .. [International Gemini Observatory/NOIRLab/NSF/AURA, J. da Silv /NA A /JPL-Caltech /B. Jónsson] ﻳﻮﻟﻴﻮ – أﻏﺴﻄﺲ 2022