Free Astronomy Magazine January-February 2024 ARABIC VERSION

T Hubble measures the size of the nearest transiting Earth-sized planet by NASA/ESA Bethany Downer he NASA/ESA Hubble Space Telescope has measured the size of the nearest Earth-sized exoplanet that passes across the face of a neighbouring star. This align- ment, called a transit, opens the door to follow-on studies to see what kind of atmosphere, if any, the rocky world might have. The diminutive planet, LTT 1445Ac, was first discovered by NASA’s Tran- siting Exoplanet Survey Satellite in 2022. But the geometry of the planet’s orbital plane relative to its star as seen from Earth was uncer- tain because TESS does not have the required optical resolution. This means the detection could have been a so-called grazing transit, where a planet only skims across a JANUARY-FEBRUARY 2024 ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 36 ﻘــ ﺲ" ﻫﺎﺑــﻞ " ــﻢ أﻗــﺮ ﺣ ﻮﻛﺐﻋﺎﺑﺮﺑﺤ ﻢ اﻷرض : ﻘﻠﻢ ﺑ ﺜﺎﻧﻲداوﻧﺮ و ﺎﻟﺔ ﻧﺎﺳﺎ / و ﺎﻟﺔ اﻟﻔﻀﺎء اﻷوروﺑ ﺔ رﺳﻢ ﺗﺨ ﻠﻲ ﻈﻬﺮ ا ﻟ ﻮﻛﺐ اﻟ ﻨ ﻤﻲ اﻟﻘﺮﺐ LTT-1445Ac ـــــــــــــﻢ اﻷرض وﻫـــــــــــــﻮ ﺑﺤ . ـــــــــــــﺪور ــــﻢ ﻗــــﺰم أ ﻤــــﺮ اﻟ ﻮﻛــــﺐﺣــــﻮل ﻧ . ﻳﻮﺟــــﺪ اﻟــــﻨ ﻢ أ ﻤــــﺮ ﻦ ﻓـــﻲ ﻧﻈـــﺎم ﺛﻼﺛــــﻲ ﻣـــﻊ وﺟــــﻮد ﻗـــﺰﻣ ـــــﺪوران ــــــﺎﻟﻘﺮ ﻣـــــﻦ ﻌﻀــــــﻬﺎ ﻋﻠـــــﻰﻣﺴــــــﺎﻓﺔ ـــــــــﺔ ﺟــــــــــﺪاً ﻗﺮ ﻓـــــــــﻲ أﻋﻠــــــــــﻰ اﻟ ﻤـــــــــ . اﻟﻨﻘﻄــــــــــﺔ اﻟﺴــﻮداء أﻣــﺎم اﻟــﻨ ﻢ اﻷ ﻣـﺎﻣﻲﻫــﻲ اﻟ ﻮﻛــﺐ -14 5Ab ﻌ اﻟﺬ أﻣﺎم ﻧ ﻤﮫ . ﻗـﺎم ﺗﻠﺴﻜﻮب ﻫﺎﺑﻞ اﻟﻔﻀﺎﺋﻲ اﻟﺘﺎﺑﻊ ﻟﻨﺎ ﺳﺎ ووﻛﺎﻟﺔ اﻟﻔﻀـﺎء اﻷوروﺑﻴـﺔ ﺑﻘﻴـﺎس ﺣﺠـﻢ أﻗﺮب ﻛﻮﻛﺐ ﻧﺠﻤﻲ ﻳﻤﺮ أﻣﺎم ا ﻪ ﻧﺠﻤ . ﺠﺎور إن ﻫﺬا اﻟﺤﺪث اﻟﻔﻠﻜﻲ اﻟﺬي ﻳُﺴﻤﻰ ﺑـﺎﻟﻌﺒﻮر ﻳﻔﺘﺢ اﻟﺒﺎب ﻗﺮﻳﺐ ﻣﻦ ﺣﺠـﻢ اﻷرض اﻟﺒـﺎب ﻋﲆ ﻣﴫاﻋﻴﻪ أﻣﺎم دراﺳﺎت ﻻﺣﻘﺔ ﻌﺮﻓـﺔ ﻧﻮع اﻟﻐﻼف اﻟﺠﻮي اﻟﺬي ﻗﺪ ﻳﻜﻮن ﻣﻮﺟـﻮد ا ﰲ ﻫﺬا اﻟﻜﻮﻛﺐ اﻟﺼﺨﺮي . ﺗﻢ اﻛﺘﺸﺎ ف اﻟﻜﻮﻛﺐ اﻟﺼﻐ LTT 1445Ac ﻷول ﻣﺮة ﺑﻮاﺳﻄﺔ اﻟﻘﻤـﺮ اﻟﺼـﻨﺎﻋﻲ ﺴـﺢ اﻟﻜﻮاﻛﺐ اﻟﺨﺎرﺟﻴﺔ اﻟﻌﺎﺑﺮة ﺗﻴﺴﺲ ) ( اﻟﺘـﺎﺑﻊ ﻟﻨﺎﺳﺎ ﰲ ﻋﺎم 2022 ﻟﻜﻦ ﻫﻨﺪﺳـﺔ ا ﺴـﺘﻮى ا ﺪاري ﻟﻠ ﻜﻮﻛﺐ ﺑﺎﻟﻨﺴﺒﺔ ﻟﻨﺠﻤﻪ ﻛﻤﺎ ﻳُﺮى ﻣﻦ اﻷرض ﻛﺎﻧﺖ ﻏـ ﻣﺆﻛـﺪة ﻷن ﺗﻴﺴـﺲ ) ﻻ ( ﻳﺘﻤﺘﻊ ﺑﺎﻟﺪﻗﺔ اﻟﺒﴫ ﻳﺔ ا ﻄﻠﻮﺑﺔ وﻫﺬا ﻳﻌﻨـﻲ أن اﻻﻛﺘﺸﺎف ﻗﺪ ﻳﻜﻮن ﻣﺎ ﻳﺴﻤﻰ ﺑ اﻟ"ـ ﻌﺒﻮر "ﻋﻲا اﻟﺮ ﺣﻴﺚ ﻳﻤﺮ اﻟﻜﻮﻛﺐ ﻋﱪ ﺟﺰء ﺻـﻐ ﻓﻘﻂ ﻣﻦ ﻗﺮص اﻟـﻨﺠﻢ اﻟـﺬي ﻳـﺪور ﺣﻮﻟـﻪ . ـــــــ - ﻳﻨﺎﻳﺮ ﻓﺒﺮﺍﻳﺮ 2 0 2 4