Free Astronomy Magazine November-December 2024 ARABIC VERSION

New light on the darkness of the Universe by NASA Michael Buckley Ray Villard ust how dark is deep space? As- tronomers may have finally an- swered this long-standing ques- tionbytappingintothecapabilities and distant position of NASA’s New Horizonsspacecraft,bymakingthe mostprecise,directmeasurements everofthetotalamountoflightthe universegenerates. Morethan18yearsafterlaunchand nine years after its historicexplo- ration of Pluto, New Horizons is morethan5.4billionmiles(7.3bil- lionkilometers)fromEarth,inare- gionofthesolarsystemfarenough from the Sun to offer the darkest skiesavailabletoanyexistingtele- scope–andtoprovideauniquevan- tage point from which to measure theoverallbrightnessofthedistant universe. “If you hold up your hand in deep space, how much light does the uni- verse shine on it?” asked Marc Post- man, an astronomer at the Space Telescope Science Institute in Balti- more and lead author of a new pa- perdetailingtheresearch,published in The Astrophysical Journal . “We now have a good idea of just how darkspacereallyis.Theresultsshow that the great majority of visible light we receive from the universe was generated in galaxies. Impor- tantly, we also found that there is noevidenceforsignificantlevels oflightproducedbysourcesnot presently known to astronomers.” The findings solve a puzzle that has perplexed scientists since the 1960s, when astronomers Arno Penzias and Robert Wilson discovered that space is pervaded by strong microwave ra- diation, which had been predictedto be left over from the creation of theuniverseitself.Thisresultled totheirbeingawardedtheNobel Prize.Subsequently,astronomersalso found evidence of backgrounds of X- rays, gamma rays and infrared radiation that also fill the sky. Detecting the background of “ordi- nary” (or visible) light – more for- mallycalledthecosmicopticalback- ﻣﺠﻠﺔ FreeAstronomy ﺎﻟﻌﺮ ﺔ 32 ﺿﻮء ﺟﺪ ﺪ ﻋﻠﻰﻇﻼم اﻟ ﻮن : ﻘﻠﻢ ﻣﺎﻳ ﻞ ﺎ ﻠﻲ و راي ﻓ ﻼرد و ﺎﻟﺔ ﻧﺎﺳﺎ ﻧﻮﻓﻤﺒﺮ - ﺩﻳﺴﻤﺒﺮ 2 0 2 4 ﻣﺎ ﻣﺪى ﻇﻠﻤﺔ اﻟﻔﻀﺎء اﻟﻌﻤﻴﻖ؟ رﺑﻤﺎ ﻳﻜﻮن ﻋﻠﻤﺎء اﻟﻔﻠﻚ ﻗـﺪ أﺟـﺎﺑﻮا أﺧـ اً ﻋـﲆ ﻫـﺬا اﻟﺴﺆال اﻟﺬي ﻇﻞ ﻳﺮاودﻫﻢ ﻣﻨﺬ أﻣﺪ ﺑﻌﻴﺪ ﻣﻦ ﺧﻼل اﻻﺳﺘﻔﺎدة ﻣﻦ ﻗﺪرات وﻣﻮﻗﻊ ا ﺴﺒﺎر اﻟﻔﻀﺎ ﻧﻴﻮ" ﺋﻲ ﻫﻮراﻳﺰوﻧﺰ " اﻟﺘـﺎﺑﻊ ﻟﻮﻛﺎﻟـﺔ ﻧﺎﺳﺎ وذﻟﻚ ﻣﻦ ﺧﻼل إﺟـﺮاء أدق ﻗﻴﺎﺳـﺎت ﻣﺒ ـﺎ ﴍة ﻋــﲆ اﻹﻃــﻼق ﻟﻜﻤﻴــﺔ اﻟﻀــﻮء اﻹﺟﻤﺎﻟﻴﺔ اﻟﺘﻲ ﻳﻮﻟﺪﻫﺎ اﻟﻜﻮن . ﺑﻌﺪ أﻛﺜﺮ ﻣﻦ 18 ﻋﺎﻣﺎً ﻣﻦ إﻃﻼﻗـﻪ وﺗﺴـﻌﺔ أﻋﻮام ﻣﻦ اﺳﺘﻜﺸﺎﻓﻪ اﻟﺘـﺎرﻳﺨﻲ ﻟﻠﻜﻮﻛـﺐ اﻟﻘﺰم ﺑﻠﻮﺗﻮ أﺻﺒﺢ " ﻧﻴﻮ ﻫﻮراﻳﺰوﻧﺰ ﻋـﲆ " ﻣﺴﺎﻓﺔ أﻛﺜﺮ ﻣﻦ 7.3 ﻣﻠﻴـﺎر ﻛﻴﻠـﻮﻣﱰ ﻣـﻦ ا ﻷرض ﰲ ﻣﻨﻄﻘﺔ ﻣـﻦ اﻟﻨﻈـﺎم اﻟﺸـ ﻤﴘـ وﻫﻲ ﻣﺴﺎﻓﺔ ﻛﺎﻓﻴﺔ ﻣـﻦ اﻟ ﺸـﻤﺲ ﻟﺘﻘـﺪﻳﻢ أﻇﻠﻢ ﺳﻤﺎء ﻣﺘﺎﺣﺔ ﻷي ﺗﻠﺴـﻜﻮب ﻣﻮﺟـﻮد وﺗﻮﻓ ﻧﻘﻄﺔ ﻣﺮاﻗﺒـﺔ ﻓﺮﻳـﺪة ﻳﻤﻜـﻦ ﻣـﻦ وﺗﻮﻓ ﻧﻘﻄﺔ ﻣﺮاﻗﺒـﺔ ﻓﺮﻳـﺪة ﻳﻤﻜـﻦ ﻣـﻦ ﺧﻼﻟﻬﺎ ﻗﻴﺎس اﻟﺴﻄﻮع اﻟﻜﲇ ﻟﻠﻜﻮن اﻟﺒﻌﻴﺪ . إذا رﻓﻌﺖ ﻳﺪك ﰲ اﻟﻔﻀﺎء اﻟﻌﻤﻴﻖ ﻓﻤﺎ ﻣﻘﺪار اﻟﻀﻮء اﻟﺬي ﻳﺸﻌﻪ اﻟﻜﻮن ﻋﻠﻴﻬﺎ؟ ﻟﻘﺪ ﺗﺴﺎءل ﻣﺎرك ﺑﻮﺳﺘﻤﺎن ﻋـﺎﻟﻢ اﻟﻔﻠـﻚ ﰲ ﻣﻌﻬﺪ ﻋﻠﻮم ﺗﻠﺴﻜﻮب اﻟﻔﻀـﺎء ﰲ ﺑـﺎﻟﺘﻴﻤﻮر وا ﺆﻟﻒ اﻟﺮﺋﻴـ ـ ﴘ ﻟﻮرﻗـﺔ ﺑﺤﺜﻴـﺔ ﺟﺪﻳـﺪة ﺗﻔﺼﻞ اﻟﺒﺤﺚ ـﻧُ ﴩت ﰲ ا ﺠﻠﺔ اﻟﻔﻴﺰﻳﺎﺋﻴـﺔ اﻟﻔﻠﻜﻴﺔ :" ﻟﺪﻳﻨﺎ اﻵن ﻓﻜﺮة ﺟﻴﺪة ﻋـﻦ ﻣـﺪى ﻇﻠﻤـﺔ اﻟﻔﻀـﺎء ﺣﻘـ . ﺎً ﺗُﻈﻬـﺮ اﻟﻨﺘـﺎﺋﺞ أن اﻟﻐﺎﻟﺒﻴﺔ اﻟﻌﻈﻤﻰ ﻣﻦ اﻟﻀـﻮء ا ﺮﺋـﻲ اﻟـ ﺬي ﻧﺘﻠﻘﺎه ﻣﻦ اﻟﻜﻮن ﺗـﻢ إﻧﺸـﺎؤه ﰲ ا ﺠـﺮات . واﻷ ﻣﺮ ا ﻬﻢ أﻧﻨﺎ وﺟﺪﻧﺎ أﻳﻀـ ﺎً أﻧـﻪ ﻻ ﻳﻮﺟـﺪ دﻟﻴﻞ ﻋﲆ ﻣﺴﺘﻮﻳﺎت ﻛﺒ ة ﻣﻦ اﻟﻀﻮء ا ﻨﺘﺞ ﻣﻦ ﻣﺼﺎدر ﻏـ ﻣﻌﺮوﻓـﺔ ﺣﺎﻟﻴـ ﺎُ ﻟﻌﻠﻤـﺎء اﻟﻔﻠﻚ ". وﺗﺤﻞ اﻟﻨﺘﺎﺋﺞ ﻟﻐﺰاً ﺣ اﻟﻌﻠﻤﺎء ﻣﻨﺬ اﻟﻔﻠﻚ وﺗﺤﻞ اﻟﻨﺘﺎﺋﺞ ﻟﻐﺰاً ﺣ اﻟ ﻌﻠﻤﺎء ﻣﻨـﺬ ﺳﺘﻴﻨﻴﺎت اﻟﻘﺮن اﻟﻌﴩﻳﻦ ﻋﻨـﺪﻣﺎ اﻛﺘﺸـﻒ اﻟﻔﻠﻜﻴﺎن أرﻧﻮ ﺑﻴﻨﺰﻳﺎس وروﺑﺮت وﻳﻠﺴـﻮن أن اﻟﻔﻀﺎء ﻣﻤﻠﻮء ﺑﺈﺷﻌﺎﻋﺎت ﻣﻴﻜﺮو وﻳـﻒ ﻗﻮﻳﺔ واﻟﺘـﻲ ﻛـﺎن ﻣـﻦ ا ﺘﻮﻗـﻊ أن ﺗﻜـﻮن ﻣﺘﺒﻘﻴﺔ ﻣﻦ ﺧﻠﻖ اﻟﻜﻮن ﻧﻔﺴﻪ . ﻟﻘﺪ أدى ﻫﺬا إﱃ ﻣﻨﺤﻬﻤﺎ ﺟـﺎﺋﺰة ﻧﻮﺑـﻞ وﰲ وﻗﺖ ﻻﺣﻖ وﺟﺪ ﻋﻠﻤﺎء اﻟﻔﻠﻚ أﻳﻀﺎً أدﻟﺔ ﻋﲆ وﺟﻮد ﺧﻠﻔﻴﺎت ﻣﻦ اﻷﺷﻌﺔ اﻟﺴﻴﻨﻴﺔ وأﺷﻌﺔ ﻏ ﺎﻣﺎ واﻷﺷﻌﺔ ﺗﺤـﺖ اﻟﺤﻤـﺮاء اﻟﺘـﻲ ﺗﻤـﻸ اﻟﺴﻤﺎء أﻳﻀﺎً . إن اﻛﺘﺸﺎف ﺧﻠﻔﻴـﺔ اﻟﻀـﻮء اﻟﻌـﺎدي " أو " ) ا ﺮﺋﻲ ( واﻟﺬي ﻳﻄﻠﻖ ﻋﻠﻴﻪ ر ﺳﻤﻴﺎً اﻟﺨﻠﻔﻴـﺔ اﻟﺒـﴫﻳﺔ اﻟﻜﻮﻧﻴﺔ ﻗـﺪم ﻃﺮﻳﻘـﺔ ﻟﺤﺴـﺎب ﻣﺠﻤﻮع ﻛﻞ اﻟﻀﻮء اﻟﺬي ﺗﻮﻟﺪ ه ا ﺠﺮات ﻋﲆ ﻣﺪار ﻋﻤﺮ اﻟﻜﻮن .