Free Astronomy Magazine January-February 2023 ARABIC VERSION

known asteroid to the Sun. As such, it has the largest general-relativity ef- fects of any object in our Solar System and during its orbit its surface gets hot enough to melt lead. “Our twilight survey is scouring the area within the orbits of Earth and Venus for asteroids,” said Scott S. Sheppard, an astronomer at the Earth and Planets Laboratory of the Carnegie Institution for Science and the lead author of the paper describ- ing this work. “So far we have found two large near-Earth asteroids that are about 1 kilometer across, a size that we call planet killers.” “There are likely only a few NEAs with similar sizes left to find, and these large undiscovered asteroids likely have orbits that keep them in- terior to the orbits of Earth and Venus most of the time,” said Shep- pard. “Only about 25 asteroids with orbits completely within Earth’s orbit have been discovered to date because of the difficulty of observing near the glare of the Sun.” Finding asteroids in the inner Solar System is a daunting observational challenge. Astronomers have only two brief 10-minute windows each night to survey this area and have to contend with a bright background sky resulting from the Sun’s glare. Ad- ditionally, such observations are very near to the horizon, meaning that as- tronomers have to observe through a thick layer of Earth’s atmosphere, which can blur and distort their ob- servations. Discovering these three new asteroids despite these challenges was possible thanks to the unique observing capa- bilities of DECam. The state-of-the-art instrument is one of the highest-per- formance, wide-field CCD imagers in the world, giving astronomers the ability to capture large areas of sky with great sensitivity. Astronomers refer to observations as ‘deep’ if they capture faint objects. When hunting for asteroids inside Earth’s orbit, the capability to capture both deep and wide-field observations is indispensa- ble. DECam was funded by the US De- partment of Energy (DOE) and was built and tested at DOE’s Fermilab. “Large areas of sky are required be- cause the inner asteroids are rare, and deep images are needed because as- teroids are faint and you are fighting the bright twilight sky near the Sun as well as the distorting effect of Earth’s atmosphere,” said Sheppard. “DECam can cover large areas of sky to depths not achievable on smaller telescopes, allowing us to go deeper, cover more sky, and probe the inner Solar System in ways never done be- fore.” As well as detecting asteroids that could potentially pose a threat to Earth, this research is an important step toward understanding the distri- bution of small bodies in our Solar System. Asteroids that are further from the Sun than Earth are easiest to detect. Because of that these more- distant asteroids tend to dominate current theoretical models of the as- teroid population. Detecting these objects also allows as- tronomers to understand how aster- oids are transported throughout the inner Solar System and how gravita- tional interactions and the heat of the Sun can contribute to their frag- mentation. “Our DECam survey is one of the largest and most sensitive searches ever performed for objects within Earth’s orbit and near to Venus’s orbit,” said Sheppard. “This is a unique chance to understand what types of objects are lurking in the inner Solar System.” “After ten years of remarkable serv- ice, DECam continues to yield impor- tant scientific discoveries while at the same time contributing to planetary defense, a crucial service that benefits all humanity,” said Chris Davis, NSF Program Director for NOIRLab. DECam was originally built to carry out the Dark Energy Survey, which was conducted by the DOE and the US National Science Foundation be- tween 2013 and 2019.     - 2023 ﻳُﻌـﺪ ٢٠٢١ PH27 أﻗـﺮب ﻛﻮﻳﻜـﺐ ﻣﻌـﺮوف ﻟﻠﺸﻤﺲ وﻫﻮ أﻳﻀًﺎ ذو أﻫﻤﻴﺔ ﺧﺎﺻﺔ ﻟﻌﻠﻤﺎء اﻟﻔﻠﻚ واﻟﻔﻴﺰﻳﺎء اﻟﻔﻠﻜﻴﺔ وذﻟﻚ ﻧﻈـﺮاً ﻷن ﻟـﻪ أﻛﱪ ﺗﺄﺛ ات اﻟﻨﺴﺒﻴﺔ اﻟﻌﺎﻣـﺔ ﻣﻘﺎرﻧـﺔ ﺑـﺄي ﺟﺴﻢ ﰲ ﻧﻈﺎﻣﻨﺎ اﻟﺸﻤﴘ إﺿﺎﻓﺔ اﻧـﻪ ﺧـﻼل ﻣﺪاره ﻳﺼﺒﺢ ﺳﻄﺤﻪ ﺳﺎﺧﻨًﺎ ﺑﺪرﺟـﺔ ﻛﺎﻓﻴـﺔ ﻹذاﺑﺔ اﻟﺮﺻﺎص . ﻗـﺎل ﺳـﻜﻮت س . ﺷـﻴﺒﺎرد ﻋﺎﻟﻢ اﻟﻔﻠـﻚ ﰲ ﻣﺨﺘـﱪ اﻷرض واﻟﻜﻮاﻛـﺐ ﰲ ﻣﻌﻬـﺪ ﻛـﺎرﻧﻴﺠﻲ ﻟﻠﻌﻠـﻮم وا ﺆﻟـﻒ اﻟـﺮﺋ ﻴﺲ ﻟﻠﻮرﻗﺔ اﻟﺘﻲ ﺗﺼﻒ ﻫﺬا اﻟﻌﻤ :ﻞ ﻟﻘﺪ ﻣﺴـﺤﻨﺎ ا ﻨﻄﻘﺔ اﻟﻮاﻗﻌﺔ داﺧﻞ ﻣﺪاري اﻷرضواﻟﺰﻫﺮة ﺑﺤﺜًـﺎ ﻋـﻦ ﻛﻮﻳﻜﺒـﺎت واﻛﺘﺸـﻔﻨﺎ ﺣﺘـﻰ اﻵن ﻛﻮﻳﻜﺒ ﻛﺒ ﻳﻦ ﺑـﺎﻟﻘﺮب ﻣـﻦ اﻷرض ﻳﺒﻠـﻎ ا ﻗﻄﺮ ﻫﻤﺎ ﺣﻮاﱄ ﻛﻴ ﻠﻮﻣﱰ واﺣﺪ وﻫـﻮ ﺣﺠـﻢ ﻧﺴﻤﻴﻪ ﻗﺎﺗﻞ اﻟﻜﻮاﻛﺐ ". ﻗﺎل ﺷـﻴﺒﺎرد " : ﻣـﻦ ا ﺤﺘﻤﻞ أﻧﻪ ﻟﻢ ﻳﺘﺒﻖ ﺳـﻮى ﻋـﺪد ﻗﻠﻴـﻞ ﻣـﻦ اﻟﻜﻮﻳﻜﺒﺎت ا ﻟﻘﺮﻳﺒﺔ ﻣﻦ اﻻرض ذات اﻷﺣﺠـﺎم ا ﺸــﺎﺑﻬﺔ وﻣ ـﻦ ا ﺤﺘﻤ ـﻞ أن ﻳﻜــﻮن ﻟﻬ ـﺬه اﻟﻜﻮﻳﻜﺒﺎت اﻟﻜﺒ ة ﻏـ ا ﻜﺘﺸـﻔﺔ ﻣـ ﺪارات ﺗﺠﻌﻠﻬﺎ داﺧﻞ ﻣﺪارات اﻷرض واﻟﺰﻫﺮة ﻣﻌﻈﻢ اﻟﻮﻗﺖ " ." ﺗﻢ اﻛﺘﺸﺎف ﺣﻮاﱄ ٢٥ ﻛﻮﻳﻜﺒًﺎ ﻓﻘﻂ ﻟﻬﺎ ﻣﺪارات داﺧﻞ ﻣﺪار اﻷرض ﺗﻤﺎﻣًـﺎ ﺣﺘـﻰ اﻵن ﺑﺴﺒﺐ ﺻﻌﻮﺑﺔ اﻟﺮﺻﺪ ﺑﺎﻟﻘﺮب ﻣﻦ وﻫﺞ اﻟﺸﻤﺲ ". ﻳُﻌـﺪ اﻟﻌﺜـﻮر ﻋـﲆ اﻟﻜﻮﻳﻜﺒـﺎت ﰲ اﻟﺠﺰء اﻟـﺪاﺧﲇ ﻣـﻦ ا ﻮﺟﻤﻮﻋـﺔ اﻟﺸﻤﺴـﻴﺔ ﺗﺤﺪﻳًﺎ ﻛﺒ اً ﰲ ﻣﺠﺎل اﻟﺮﺻـ . ﺪ ﻳﻤﺘﻠـﻚ ﻋﻠﻤـﺎء اﻟﻔﻠﻚ ﻓﺮﺻﺘ ﻗﺼ ﺗ ا ـ ﻟ ﺪة ﻜـﻞ ﻣﻨﻬﻤـﺎ ﺣﻮاﱄ ١٠ دﻗﺎﺋﻖ ﺿﻤﻦ ﻛﻞ ﻟﻴﻠﺔ ﺴـﺢ ﻫـﺬه ا ﻨﻄﻘﺔ وﻋﻠﻴﻬﻢ اﻟﺘﻌﺎﻣﻞ ﻣﻊ ﺧﻠﻔﻴﺔ اﻟ ﺴـﻤﺎء ا اﻟﴩﻗﺔ ﻨﺎﺗﺠﺔ ﻋﻦ وﻫﺞ اﻟﺸﻤﺲ . ﺑﺎﻹﺿﺎﻓﺔ إﱃ ذﻟﻚ ﻓﺈن ﻣﺜﻞ ﻫﺬه اﻷرﺻﺎد ﻗﺮﻳﺒﺔ ﺟﺪًا ﻣﻦ اﻷﻓﻖ ﻣﻤﺎ ﻳﻌﻨﻲ أﻧﻪ ﻳﺘﻌ ﻋـﲆ اﻟﻔﻠﻜﻴـ أن ﻳﺮﺻﺪوا ﻣﻦ ﺧﻼل ﻃﺒﻘﺔ ﺳﻤﻴﻜﺔ ﻣﻦ اﻟﻐﻼف اﻟﺠ ـﻮي ﻟ ـﻸرض واﻟﺘ ـﻲ ﻳﻤﻜ ـﻦ أن ﺗﺸـﻮه ارﺻﺎدﻫﻢ ﻟﻘﺪ . ﻛﺎن اﻛﺘﺸﺎف ﻫﺬه اﻟﻜﻮﻳﻜﺒﺎت اﻟﺜﻼﺛﺔ اﻟﺠﺪﻳﺪة ﻋﲆ اﻟﺮﻏﻢ ﻣﻦ ﻫﺬه اﻟﺘﺤﺪﻳﺎت ﻣﻤﻜﻨًﺎ ﺑﻔﻀﻞ ﻗﺪرات ا ﺮاﻗﺒﺔ اﻟﻔﺮﻳﺪة ﻟﻜﺎﻣ ا اﻟﻄﺎﻗـﺔ ا ﻈﻠﻤــﺔ ) دي ﻛـﺎم .( ﺘ ـﱪ ﺗﻌ ﻫــﺬه اﻟﻜﺎﻣ ا اﻟﺮﻗﻤﻴﺔ اﻷﻛﺜﺮ ﺣﺪاﺛـﺔ واﺣـﺪة ﻣـﻦ أﺟﻬﺰة اﻟﺘﺼﻮﻳﺮ ) ( ﳼﳼ دي ذات ا ﺠﺎل ﻣﺠﻠﺔ Astronomy ﺎﻟﻌﺮ ﺔ ٢٣ ٢٤ اﻟﻮاﺳﻊ واﻷﻋﲆ دﻗـﺔ ﰲ اﻟﻌـﺎﻟﻢ ﻣﻤـﺎ ﻳﻤـﻨﺢ ﻋﻠﻤﺎء اﻟﻔﻠﻚ اﻟﻘﺪرة ﻋﲆ اﻟﺘﻘـﺎط ﻣﺴـﺎﺣﺎت ﻛﺒ ة ﻣﻦ اﻟﺴﻤﺎء ﺑﺤﺴﺎﺳﻴﺔ ﻛﺒـ ة . ﻳﺸـ ﻋﻠﻤﺎء اﻟﻔﻠﻚ إﱃ اﻷرﺻﺎد " ﻋﲆ أﻧﻬـﺎ " ﻋﻤﻴﻘـﺔ إذا اﻟﺘﻘﻄﻮا أﺟﺴﺎﻣًﺎ ﺑﺎﻫﺘﺔ ﻨﺪ ا ﻋ ﻟﺒﺤـﺚ ﻋـﻦ ﻛﻮﻳﻜﺒﺎت داﺧـﻞ ﻣـﺪار اﻷرض ﻻ ﻏﻨـﻰ ﻋـﻦ اﻟﻘﺪرة ﻋﲆ اﻟﺘﻘﺎط أرﺻﺎد ﻋﻤﻴﻘﺔ وﻋﺮﻳﻀـﺔ ا ﺠﺎل ﻟﻘﺪ . ﺗﻢ ﺗﻤﻮﻳﻞ ﻛﺎﻣ ا اﻟﻄﺎﻗﺔ ا ﻈﻠﻤﺔ ) دي ﻛﺎم ( ﻣﻦ ﻗﺒﻞ وزارة اﻟﻄﺎﻗـﺔ اﻷﻣﺮﻳﻜﻴـﺔ وﺗﻢ ﺑﻨﺎؤﻫ ﺎ واﺧﺘﺒﺎرﻫـ ﺎ ﰲ ﻣﺨـﱪ ﻓ ﻣـﻴﻼب اﻟﺘﺎﺑﻊ ﻟﻮزارة اﻟﻄﺎﻗﺔ . ﻗﺎل ﺷﻴﺒﺎرد " : ﻣﻄﻠﻮب ﻣﺴﺎﺣﺎت ﻛﺒ ة ﻣﻦ اﻟﺴﻤﺎء ﻷن اﻟﻜﻮﻳﻜﺒـﺎت اﻟﺪاﺧﻠﻴﺔ ﻧﺎدرة وﻫﻨﺎك ﺣﺎﺟﺔ إﱃ ﺻﻮر ﻋﻤﻴﻘﺔ ﻷن اﻟﻜﻮﻳﻜﺒﺎت ﺧﺎﻓﺘـﺔ وأﻧـﺖ ﺗﻮاﺟـﻪ ﺿـﻮء اﻟ ﺸ ـﻔﻖ اﻟﺴــﺎﻃﻊ ﺑــﺎﻟﻘﺮب ﻣ ـﻦ اﻟﺸ ـﻤﺲ ﺑﺎﻹﺿﺎﻓﺔ إﱃ اﻟﺘﺄﺛ ا ﺸـﻮه ﻟﻠﻐـﻼف اﻟﺠـﻮي ﻟﻸرض ﻳﻤﻜﻦ ﻟ " ". ) ﻜﺎﻣ ا دي ﻛﺎم ( ﺗﻐﻄﻴـﺔ ﻣﺴﺎﺣﺎت ﻛﺒـ ة ﻣـﻦ اﻟﺴـﻤﺎء إﱃ أﻋﻤـﺎق ﻻ ﻳﻤﻜﻦ ﺗﺤﻘﻴﻘﻬﺎ ﺑﺎﺳﺘﺨﺪام ﺗﻠﺴﻜﻮﺑﺎت أﺻﻐﺮ ﻣﻤﺎ ﻳﺴﻤﺢ ﻟﻨﺎ ﺑﺎﻟﺘ ﻌﻤﻖ أﻛﺜﺮ وﺗﻐﻄﻴﺔ ا ﺰﻳـﺪ ﻣﻦ اﻟﺴﻤﺎء واﺳﺘﻜﺸﺎف ا ﺠﻤﻮﻋﺔ اﻟﺸﻤﺴﻴﺔ ﺑﻄـﺮق ﻟـﻢ ﺗ ﺤــﺪث ﻣـﻦ ﻗﺒـﻞ ﺑﺎﻹﺿـﺎﻓﺔ إﱃ اﻛﺘﺸﺎف اﻟﻜﻮﻳﻜﺒﺎت اﻟﺘﻲ ﻳﺤﺘﻤـﻞ أن ﺗﺸـﻜﻞ ﺗﻬﺪﻳﺪاً ﻟﻸرض وﻫﻲ ﺧﻄﻮة ﻣﻬﻤﺔ ﻧﺤﻮ ﻓﻬـﻢ أﻓﻀﻞ ﻟ ﺘﻮزﻳﻊ اﻷﺟﺴﺎم اﻟﺼﻐ ة ﰲ ا ﺠﻤﻮﻋﺔ اﻟﺸﻤﺴ .ﻴﺔ إن اﻟﻜﻮﻳﻜﺒـﺎت اﻟﺘـﻲ ﺗﺒﻌـﺪ ﻋـﻦ اﻟﺸ ـﻤﺲ أﻛﺜــﺮ ﻣ ـﻦ اﻷرض ﻫــﻲ اﻷﺳ ـﻬﻞ اﻛﺘﺸﺎﻓﺎً و ﺗﻤﻴﻞ إﱃ اﻟﺴـﻴﻄﺮة ﻋـﲆ اﻟﻨﻤـﺎذج اﻟ ﻨﻈﺮﻳﺔ اﻟﺤﺎﻟﻴﺔ ﻟ ﺘﺠﻤـﻊ اﻟﻜﻮﻳﻜﺒـﺎت . ﻳﺘـﻴﺢ اﻛﺘﺸﺎف ﻫﺬه اﻷﺟﺴـﺎم أﻳﻀًـﺎ ﻓﻬـﻢ ﻛﻴﻔﻴـﺔ اﻧﺘﻘﺎل اﻟﻜﻮﻳﻜﺒﺎت ﻣﻦ ﺧﻼل اﻟﻨﻈﺎم اﻟﺸﻤﴘ اﻟﺪاﺧﲇ وﻛﻴـﻒ ﻳﻤﻜـﻦ ﻟﺘﻔـﺎﻋﻼت اﻟﺠﺎذﺑﻴـﺔ وﺣﺮارة اﻟﺸﻤﺲ أن ﺗﺴﺎﻫﻢ ﰲ ﺗﻔﺘﻴﺘﻬﺎ . ﻗـﺎل : " ﺷﻴﺒﺎرد ﻳﻌﺪ ﻣﺴﺢ اﻟﺴﻤﺎء ﺑﻮاﺳﻄﺔ ﻛﺎﻣ ا ) دي ﻛﺎم اﻟﺨﺎﺻ ( ﺔ ﺑﻨـﺎ أﺣـﺪ أﻛـﱪ ﻋﻤﻠﻴـﺎت اﻟﺒﺤﺚ وأﻛﺜﺮﻫﺎ ﺣﺴﺎﺳﻴﺔ ﻋﲆ اﻹﻃـﻼق ﻋـﻦ اﻷﺟﺴﺎم ا ﻮﺟﻮدة ﰲ ﻣـﺪار اﻷرض وﺑـﺎﻟﻘﺮب ﻣﻦ ﻣﺪار ﻛﻮﻛﺐ اﻟﺰﻫﺮة إن . ﻫﺬه ﻓﺮﺻﺔ ﻓﺮﻳﺪة ﻟﻔﻬ ـﻢ أﻧ ـﻮاع اﻷﺷــﻴﺎء اﻟ ﻜﺎﻣﻨــﺔ ﰲ اﻟﻨﻈ ـﺎم اﻟﺸﻤﴘ اﻟﺪاﺧﲇ . اﻟﻴﻮم ﺑﻌﺪ ﻋﴩﺳﻨﻮات ﻣﻦ اﻟﺨﺪﻣﺔ ﺗ ﻮاﺻﻞ ﻛـﺎﻣ ا ) دي ﻛـﺎم ( ﺗﺤﻘﻴـﻖ اﻛﺘﺸﺎﻓﺎت ﻋﻠﻤﻴﺔ ﺗﻔﻴﺪ اﻟﺒﴩﻳﺔ ﺟﻤﻌﺎء ". ﻷ ﻣﻜﻨــــﺖ أ ــــﺔ ﻓــــﻲ ــــﺎﻣ ا اﻟﻄﺎﻗــــﺔ اﻟﻤﻈﻠﻤــــﺔ اﻟﻤﺼــــﻨّﻌﺔ ﻣــــﻦ وزارة اﻟﻄﺎﻗــــﺔ اﻷﻣﺮ ﻜ رﺻــــﺎد ﺎﺳــــﺘﺨﺪام ﻣﺮﺻ ﺪ ﺳ و ﺗﻮﻟﻮﻟﻮ اﻟﺪوﻟﻲﻓﻲ ﺗﺸ ﻠﻲ وﻫﻮ ﺑﺮ ﺎﻣﺞ ﻟﻠﻤﺨﺘ اﻟﻮﻃ ﻟﺒﺤﻮث اﻟﻔﻠﻚ ﺎﻷﺷﻌﺔ ﺗﺤـﺖ اﻟــ ﻤﺮاء اﻟﻀــﻮﺋ ﺔ ) ﻧــﻮﻳﺮﻻب ( ـﺔ ، ﻋﻠﻤــﺎء اﻟﻔﻠــﻚﻣـﻦ اﻛﺘﺸــﺎف ﺛﻼﺛــﺔ اﻟﺘـﺎﺑﻊ ﻟﻤﺆﺳﺴــﺔ اﻟﻌﻠــﻮم اﻟﻮﻃﻨ ﻮ ﻜ ﺎت ﻗﺮ ﺔ ﻣﻦ اﻷرضﻣﺨﺘﺒﺌـﺔ ﻓـﻲوﻫـﺞ اﻟﺸـﻤﺲ . ـﺔ ﻣـﻦ اﻷرضﻫـﻲﺟـﺰء ﻫـﺬﻩ اﻟﻤﻨـﺎﻃﻖ اﻟﻘﺮ ـﺪة اﻟﻤﻨــﺎل ﺗـ ﺺداﺧـﻞ ﻣـﺪارات اﻷرضواﻟﺰﻫـﺮ ﻣـﻦ ﻣ ﻤﻮﻋـﺔﺳـ ﺎﻧ ﺔ ﻌ . ة ـﺎتﻫـﻮ أﻛــ أﺣـﺪ اﻟ ﻮ ﻜ ﺟﺴﻢ ﻳُﺤﺘﻤﻞ أن ﺸ ﻞ ﺧﻄﺮًا ﻋﻠﻰ اﻷرض ﺘﻢ اﻛﺘﺸﺎﻓﮫ ﻓﻲ اﻟﺴﻨﻮات اﻟﺜﻤﺎﻧﻲ اﻟﻤﺎﺿ ﺔ . ﻳﻨﺎﻳﺮ ﻓ اﻳﺮ 2023