Free Astronomy Magazine September-October 2022 ARABIC VERSION

without assuming the exis- tence of the phantom Planet X. A study of the measure- ments made by the Voyager 2 probe revealed that the ir- regularities observed in the motion of Uranus were sim- ply due to a slight overesti- mation of the mass of Nep- tune. Subsequent improve- ments in our understanding of the latter's orbit made the existence of another planet completely superflu- ous. Without a starting point in the form of gravita- tional perturbations of the outer planets, there was no longer any way to calculate to an acceptable approxima- tion the position in the sky of some possible Planet X and then go out and look for it. The most stubborn as- tronomers still searching for Planet X could only make rough assump- tions about its mass and orbital properties given the instrumental, tem- poral and spatial limits of all the surveys carried out up to that time. A planet of 4-5 Earth masses at least 200 AU from the Sun, or a pro- portionately larger planet even further out, would have been unde- tectable using the tech- nology of the 1990s even in the infrared, the domain of wavelengths where a body so far away would be ex- pected to peak in its electromagnetic radia- tion. In the last thirty years, many works have been published that have placed further re- strictions on the exis- ﻣﺠﻠﺔ Astronomy ﺎﻟﻌﺮ ﺔ ٣٦ ﻛﺸـﻔﺖ دراﺳـﺔ ﻟﻠﻘﻴﺎﺳـﺎت اﻟﺘﻲ أﺟﺮاﻫﺎ ﻣﺴﺒﺎر ﻓﻮﻳـﺎﺟﺮ ٢ أ اﻟﺘــﺎﺑﻊ ﻟﻮﻛﺎﻟ ـﺔ ﻧﺎﺳ ـﺎ أن اﻟﺘﻐــ ات اﻟﺘــﻲ رﺻــﺪت ﰲ ﺣﺮﻛﺔ ﻛﻮﻛﺐ أوراﻧﻮس ﻛﺎﻧﺖ ﺑﺒﺴــﺎﻃﺔ ﺑﺴــﺒﺐ ا ﺒﺎﻟﻐــﺔ اﻟﻄﻔﻴﻔــﺔ ﰲ ﺗﻘــﺪﻳﺮ ﻛ ﺘﻠــﺔ ﻧﺒﺘﻮن . ﻟﻘﺪ أدت اﻟﺘﺤﺴـﻴﻨﺎت اﻟﻼﺣﻘﺔ ﰲ ﻓﻬﻤﻨﺎ ﺪار اﻷﺧ إﱃ ﺟﻌﻞ وﺟـﻮد ﻛﻮﻛـﺐ آﺧـﺮ ﻏـ ﴐوري ﺗﻤﺎﻣًـﺎ . ﺑـﺪون ﻧﻘﻄـــﺔ ﺑﺪاﻳـــﺔ ﰲ ﺷـــﻜﻞ اﺿﻄﺮاﺑﺎت اﻟﺠﺎذﺑﻴﺔ ﻟﻠﻜﻮاﻛﺐ اﻟﺨﺎرﺟﻴﺔ ﻟﻢ ﻳﻌﺪ ﻫﻨـﺎك أي ﻃﺮﻳﻘــﺔ ﻟﺤﺴــﺎب ﺗﻘﺮﻳﺒــ ﻲ ﻣﻘﺒﻮل ﻮﺿﻊ اﻟﻜﻮﻛﺐ اﻛﺲ ﰲ اﻟﺴﻤﺎء ﺛﻢ اﻟﺨﺮوج واﻟﺒﺤﺚ . ﻋﻨﻪ ﻟـﻢ ﻳﻜـﻦ ﺑ ﻮﺳـﻊ أﻛﺜـﺮ ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﻋﻨﺎدًا ﰲ اﻟﺒﺤـﺚ ﻋﻦ ﻫـﺬا اﻟﻜﻮﻛـﺐ ا ﺤﺘﻤـﻞ ـــــ ﺑ ﺳﻮى اﻟﻘﻴﺎم ﻮﺿـﻊ اﻓﱰاﺿـﺎت ﺗﻘﺮﻳﺒﻴﺔ ﺣﻮل ﻛﺘﻠﺘﻪ وﺧﺼﺎﺋﺼﻪ ا ﺪارﻳ ـﺔ ﻧﻈــﺮًا ﻟﻠﺤـﺪود اﻵﻟﻴ ـﺔ واﻟﺰﻣﺎﻧﻴــﺔ وا ﻜﺎﻧﻴــﺔ ﻟﺠﻤﻴــﻊ ا ﺴـﻮﺣﺎت اﻟﺘـﻲ أﺟﺮﻳـﺖ ذﻟـﻚ اﻟﻮﻗـﺖ إن . ﺎً ﻛﻮﻛﺒـ ﻛﺘﻠﺘـﻪ ﺗﺒﻠـﻎ ) ﺑ ٤- ٥( ﻛﺘﻠﺔ أرﺿـﻴﺔ وﻳﺒﻌـﺪ ﻋﻦ اﻟﺸﻤﺲ ) ٢٠٠ ( وﺣﺪة ﻓﻠﻜﻴﺔ ﺐﻛﻮﻛ أو ﻋﲆ اﻷﻗﻞ، أﺑﻌﺪ ﻣﻦ ذﻟﻚ ﻣﻦ ا ﻤﻜﻦ أن ﻳﻜﻮن ﻏـ ﻗﺎﺑـﻞ ﻟﻠﻜﺸـــﻒ ﺑﺎﺳــﺘﺨﺪام ﺗﻘﻨﻴـــﺔ اﻟﺘﺴــﻌ ﻴﻨﻴﺎت ﺣﺘــﻰ ﰲ اﻷﺷــﻌﺔ ﺗﺤﺖ اﻟﺤﻤﺮاء ، ﻓﻤﺠـﺎل اﻷﻃـﻮال ا ﻮﺟﻴﺔ ﺣﻴﺚ ﻳﻜﻮن اﻟﺠﺴﻢ ﺑﻌﻴﺪًا ا ﺟﺪً ة ذرو ﺑﻠﻐﺖ ﻧﺸﺎط إﺷﻌﺎﻋﻬﺎ اﻟﻜﻬﺮوﻣﻐﻨﺎﻃﻴﴘ لﺧﻼ ٣٠ ﻋﺎﻣًﺎ ا ﺎﺿﻴﺔ ، إﺿﺎﻓﺔ ﻟﺬﻟﻚ ﻟﻘﺪ ﻧُﴩت ﻋـﺪة دراﺳـﺎت ﻗﺎﻣـﺖ ﺑ ﻔـﺮض اﻟﻌﺪﻳ ــــﺪ ﻣ ــــﻦ اﻟ ﻘﻴ ــــﻮد ــــــــــــــــــــ ﺳﺒﺘﻤ أﻛﺘﻮﺑﺮ 2022 أﻛ ﺳﺘﺔ أﺟﺴﺎمﻣﻌﺮوﻓﺔ ﻌﺪًا ﻓـﻲ اﻟﻨﻈـﺎم اﻟﺸﻤﺴـﻲ، ﻣـﻊ ﻣـﺪارات ﺗﺘ ﺠـﺎوز ﻮﻛـﺐ ﻧ ﺘـﻮن ) أرﺟـﻮاﻧﻲورد ( ، ﺗﺼـﻄﻒ ﻤ ﻌﻬـﺎ ﺸـ ﻞ ﻏـﺎﻣﺾﻓـﻲ اﺗﺠـﺎﻩ واﺣـﺪ . ـﺪًا ﻋـﻦ ًـﺎ ﻌ أ ﻀًـﺎ ، ﻋﻨـﺪ ﻋﺮﺿـﻬﺎ ﺛﻼﺛـﻲ اﻷ ﻌـﺎد ، ﻓﺈﻧﻬـﺎ ﺗﻤﻴـﻞ ﺸـ ﻞ ﻣﻤﺎﺛـﻞ ﺗﻘﺮ ﻣﺴـﺘﻮى اﻟﻨﻈـﺎم اﻟﺸﻤﺴـﻲ . أﻇﻬـﺮ اﻟ ﺎﺣﺜـﺎن و ــﺎﺗﻴﺠ ﻮﻧﺴـﺘﺎﻧﺘ ـﺎ أﻧــﮫ ـﺎ ﻟﻠﺘﻜﻨﻮﻟﻮﺟ ـﻚ ﺑـﺮاون ﻣـﻦ ﻣﻌﻬـﺪ ﺎﻟ ﻔﻮر ﻣﺎ ﻔــــ ضوﺟــــﻮد ًــــﺎ ﻛﺘﻠﺘــــﮫ ﻮﻛ ﻋﺸــــﺮة أﺿــــﻌﺎفﻛﺘﻠــــﺔ اﻷرضﻓــــﻲﻣــــﺪار ــــﺎﺧﺘﻼفﻣﺮﻛــــﺰي ــــﺪ ﻌ وﻣﻀــــﺎد ﻟﻼﺻــــﻄﻔﺎفﻣــــﻊ اﻷﺟﺴﺎم اﻟﺴﺘﺔ اﻷﺧﺮى ) اﻟ ﻘﺎﻟﻲ ( ﻟﻠﺤﻔﺎظﻋﻠﻰﻫﺬا اﻟﺘ ﻮﻳﻦ . [Caltech/R. Hurt (IPAC)] إن اﻟﻨﺘﻴﺠــﺔ اﻟﻤﺘﻮﻗﻌــﺔ ﻟﻮﺟــﻮد اﻟ ﻮﻛــﺐ اﻟﺘﺎﺳــﻊ ﻫــﻲ أن ــﺔ ﻣــﻦ اﻷﺟﺴــﺎمﺿــﻤﻦ ﻧﻄــﺎقﻣﺤــﺪد ﻣ ﻤﻮﻋــﺔ ﺛﺎﻧ ﻳﺠــﺐ أن ــﻮن ﻣﻮﺟــﻮدة ﺗ أ ﻀًـــﺎ . ــﺘﻢ د ﻓـــﻊ ﻫــﺬﻩ اﻷﺟﺴـــﺎم إﻟــﻰ اﺗﺨــﺎذ ﻣﻮاﻗـــﻊ ــﺎ ﻗﺎﺋﻤـــﺔ ﺑﺰوا ﺎﻟﻨﺴــ ﺔ اﻟ ﻮﻛـــﺐ اﻟﺘﺎﺳــﻊ وﻓـــﻲ ـﺔ ﻋﻠــﻰﻣﺴــﺘﻮى اﻟﻨﻈـﺎم اﻟﺸﻤﺴــﻲ ﻣـﺪارات ﻋﻤﻮد . ﻤﺴـﺔ أﺟﺴــﺎمﻣﻌﺮوﻓـﺔ ) اﻟﻠــﻮن اﻷزرق ( ﺗﺘﻨﺎﺳــﺐ ﺗﻤﺎﻣًــﺎ ﻣــﻊ . ﻫﺬا اﻟﺘﻮﻗﻊ [Caltech/R. Hurt (IPAC) − Diagram was created using WorldWide Telescope]