Free Astronomy Magazine March-April 2025 ARABIC VERSION

T Exocomet belts are changing our understanding of planetarysystems byALMAObservatory NicolásLira5BárbaraFerreira he Edgeworth-Kuiper Belt (or simply the Kuiper Belt) is a hugestructureextending30 to 50 times the distance from the Earth to the Sun. It is full of icy and rocky objects. But where does it come from? In its infancy, the Sun was sur- rounded by a giant rotating cloud of gas and dust. Much like makingapizzafromaballofdough,byr o- tatingovertime,thecloudeventu- allybecameaflatdisc,whichwecall a protoplanetary disc. There, grains of dust collided and fused into increasingly large struc- tures. Once they reached a kilome- ter-size, their own gravity started to attract more objects, fueling their growth even further. In a very sum- marized version, this is how wethink planets formed. We have seen this process taking place in other planetarysystems.However,wealso know that not all dust ends up forming planets. Astronomers think that the influ- enceoflargeplanetslikeNeptune ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 22 أﺣﺰﻣﺔ اﻟﻤﺬﻧ ﺎت اﻟﻨ ﻤ ﺔ ﺗﻐ ﻓﻬﻤﻨﺎ ﻟﻸﻧﻈﻤﺔ اﻟ ﻮﻛﺒ ﺔ : ﻘﻠﻢ ﻧﻴ ﻮﻻس ﻟ ا و ﺎر ﺮا ﻓ ﺮا ﻣﺮﺻﺪ أﻟﻤﺎ ﺣـﺰام إﻳﺪﺟﻮرث ﺎﻛ ﻳﱪ أو ﺑﺒﺴـﺎﻃﺔ ﺣـﺰام ﻳﱪﺎﻛ ﻫﻮ ﺑﻨﻴﺔ ﺿﺨﻤﺔ ﺗﻤﺘﺪ ﻣـﻦ 30 إﱃ 50 ﺿﻌﻒ ا ﺴﺎﻓﺔ ﻣﻦ اﻷرض إﱃ اﻟﺸﻤﺲ وﻫﻮ ﻣ ﲇء ﺑﺎﻷﺟﺴﺎم اﻟﺠﻠﻴﺪﻳﺔ واﻟﺼﺨﺮﻳﺔ وﻟﻜـﻦ أ ﻣﻦ ﺄ ﻳﻦ ﻳ ﺗﻲ ﻫﺬا اﻟﺤﺰام؟ ﻟﻘـﺪ ﻛﺎﻧـﺖ اﻟﺸـﻤﺲ ﻣﻬـﺪﻫﺎ ﰲ ﻣﺤﺎﻃـﺔ ﺑﺴﺤﺎﺑ ﺔ ﻋﻤﻼﻗﺔ دوارة ﻣﻦ اﻟﻐـﺎز واﻟﻐﺒـﺎر وﻛﻤﺎ ﻫﻮ اﻟﺤﺎل ﻣﻊ ﺻﻨﻊ اﻟﺒﻴﺘﺰا ﻣـﻦ ﻛـﺮة ﻣﻦ اﻟﻌﺠ ﻣﻦ ﺧﻼل اﻟ ﺪوران ﺑﻤﺮور اﻟﻮﻗﺖ أﺻﺒﺤﺖ اﻟﺴﺤﺎﺑﺔ ﰲ اﻟﻨﻬﺎﻳﺔ ﻗﺮﺻﺎً ﻣﺴﻄﺤﺎً واﻟﺬي ﻧﺴﻤﻴﻪ اﻟﻘﺮص اﻟﻜﻮﻛﺒﻲ اﻷوﱄ . ﻫﻨﺎك اﺻﻄﺪﻣﺖ ﺣﺒﻴﺒﺎت اﻟﻐﺒﺎر واﻧـﺪﻣ ﺠﺖ ﻟﺘﺸــﻜﻞ ﻫﻴﺎﻛـﻞ ﺿـﺨﻤﺔ ﺑﺸـﻜﻞ ﻣﺘﺰاﻳـﺪ وﺑﻤﺠ ﺮد أن وﺻﻠﺖ إﱃ ﺣﺠﻢ واﺣﺪ ﻛﻴﻠـﻮﻣﱰ ﺑﺪأت ﺟﺎذﺑﻴﺘﻬﺎ اﻟﺨﺎﺻﺔ ﰲ ﺟﺬب ا ﺰﻳﺪ ﻣـﻦ اﻷﺟﺴﺎم ﻣﻤﺎ أدى إﱃ زﻳﺎدة ﻧﻤﻮﻫـﺎ ﺑﺸـﻜﻞ أﻛﱪ ﰲ ﻧ . ﺴﺨﺔ ﻣﺨﺘﴫة ﻟﻠﻐﺎﻳﺔ ﻫـﺬه ﻫـﻲ اﻟﻄﺮﻳﻘﺔ اﻟﺘﻲ ﻧﻌﺘﻘﺪ أن اﻟﻜﻮاﻛـﺐ ﺗﺸـﻜﻠﺖ . ﺑﻬﺎ ﻟﻘﺪ رأﻳﻨﺎ ﻫﺬه اﻟ ﻌﻤﻠﻴﺔ ﺗﺤﺪث ﰲ أﻧﻈﻤﺔ ﻛﻮﻛﺒﻴﺔ أﺧـﺮى وﻣـﻊ ذﻟـﻚ ﻧﻌﻠـﻢ أﻳﻀًـﺎ أن اﻟﻐﺒﺎر ﻻ ﻳﻨﺘﻬﻲ ﺑﻪ اﻷﻣﺮ إﱃ ﺗﻜﻮﻳﻦ ﻛﻮاﻛﺐ . ﻳﻌﺘﻘـﺪ ﻋﻠﻤـﺎء اﻟﻔﻠـﻚ أن ﺗـﺄﺛ اﻟﻜﻮاﻛــﺐ ــــــ ﺃﺑﺮﻳﻞ - ﻣﺎﺭﺱ 2 0 2 5