Komeet: Verskil tussen weergawes
Content deleted Content added
kNo edit summary |
k →Kern |
||
Lyn 40:
Die oppervlak van die kern is gewoonlik droog, stowwerig of rotsagtig. Dit dui daarop dat die ys verberg lê onder ’n oppervlakkors van verskeie meters dik. Benewens die gasse wat reeds genoem is, bevat die kern ’n verskeidenheid [[Organiese chemie|organiese verbindings]], wat kan insluit [[metanol]], [[waterstofsianied]], [[formaldehied]], [[etanol]] en [[etaan]] en dalk meer komplekse molekules soos [[aminosuur|aminosure]].<ref>{{cite web |last=Meech |first=M. |title=1997 Apparition of Comet Hale–Bopp: What We Can Learn from Bright Comets |url=http://www.psrd.hawaii.edu/Feb97/Bright.html |publisher=Planetary Science Research Discoveries |date=24 Maart 1997 |accessdate=30 April 2013}}</ref><ref>{{cite web |title=Stardust Findings Suggest Comets More Complex Than Thought |url=http://stardust.jpl.nasa.gov/news/news110.html |publisher=NASA |date=14 Desember 2006 |accessdate=31 Julie 2013}}</ref>
{| class=wikitable style="float: right; margin-left: 0.5em;"
Line 55 ⟶ 54:
|Wild || {{nowrap|5,5 × 4 × 3,3}}<ref name=wild2>{{cite web|title=Comet 81P/Wild 2|publisher=The Planetary Society|url=http://www.planetary.org/explore/topics/asteroids_and_comets/wild2.html|accessdate=November 20, 2007}}</ref> || 0,6<ref name=Britt2006/> || 2,3{{e|13}}
|}
In 2009 is bevestig dat die aminosuur glikokol gevind is in die komeetstof wat [[Nasa]] se Stardust-sending versamel het.<ref>{{cite journal |doi=10.1111/j.1945-5100.2009.tb01224.x |title=Cometary glycine detected in samples returned by Stardust |year=2009 |last1=Elsila |first1=Jamie E. |last2=Glavin |first2=Daniel P. |last3=Dworkin |first3=Jason P. |journal=Meteoritics & Planetary Science |volume=44 |issue=9 |pages=1323|bibcode = 2009M&PS...44.1323E }}</ref> In Augustus 2011 is ’n verslag gepubliseer wat op Nasa se bestudering van [[Meteoor|meteoriete]] geskoei was, en daarin is die moontlikheid genoem dat [[DNS]]- en [[RNS]]-komponente (adenien, guanien en verwante organiese molekules) op [[asteroïde]]s en komete gevorm het.<ref name="Callahan">{{cite journal |doi=10.1073/pnas.1106493108 |title=Carbonaceous meteorites contain a wide range of extraterrestrial nucleobases |year=2011 |last1=Callahan |first1=M.P. |last2=Smith |first2=K.E. |last3=Cleaves |first3=H.J. |last4=Ruzicka |first4=J. |last5=Stern |first5=J.C. |last6=Glavin |first6=D.P. |last7=House |first7=C.H. |last8=Dworkin |first8=J.P. |journal=Proceedings of the National Academy of Sciences |volume=108 |issue=34 |pages=13995|bibcode = 2011PNAS..10813995C }}</ref><ref name="Steigerwald">{{cite web |last=Steigerwald |first=John |title=NASA Researchers: DNA Building Blocks Can Be Made in Space |url=http://www.nasa.gov/topics/solarsystem/features/dna-meteorites.html |publisher=NASA |date=8 Augustus 2011 |accessdate=31 Julie 2013}}</ref>
Die buitenste oppervlak van komeetkerns het ’n baie lae [[albedo]]
Komeetkerns met ’n radius van net 30 km is al waargeneem,<ref>{{cite journal |doi=10.1023/A:1021545031431 |year=2000 |last1=Fernández |first1=Yanga R. |journal=Earth, Moon, and Planets |volume=89 |pages=3|bibcode = 2000EM&P...89....3F }}</ref> maar dit is moeilik om hul presiese grootte te meet.<ref>{{cite web |url=http://www2.ess.ucla.edu/~jewitt/nucleus.html |title=The Cometary Nucleus |publisher=Department of Earth and Space Sciences, UCLA |date=April 2003 |accessdate=31 Julie 2013}}</ref> Die deursnee van Komeet P/2007 R5 se kern is moontlik net 100-200 meter.<ref name=soho>{{cite web |title=SOHO's new catch: its first officially periodic comet |publisher=European Space Agency |url=http://www.esa.int/Our_Activities/Space_Science/SOHO_s_new_catch_its_first_officially_periodic_comet |accessdate=16 Augustus 2013}}</ref> Omdat geen kleiner komete al ontdek is nie ondanks instrumente wat al hoe sensitiewer word, glo sommige kenners daar is bitter min komete wat kleiner as 100 meter breed is.<ref>{{harvnb|Sagan|Druyan|1997|p=137}}</ref> Daar word geraam die bekende komete het ’n gemiddelde digtheid het van 0,6 [[Gram|g]]/cm<sup>3</sup>.<ref name=Britt2006>{{cite journal |bibcode=2006LPI....37.2214B |title=Small Body Density and Porosity: New Data, New Insights |last1=Britt |first1=D. T. |last2=Consolmagno |first2=G. J. |last3=Merline |first3=W. J. |volume=37 |year=2006 |pages=2214 |journal=37th Annual Lunar and Planetary Science Conference |url=http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2214.pdf }}</ref> Vanweë hul lae massa word komeetkerns nie deur hul swaartekrag [[Hidrostatiese ewewig|in ’n ronde bol gedruk]] nie en daarom het hulle onreëlmatige vorms.<ref>{{cite web |url=http://history.nasa.gov/SP-467/ch7.htm |title=The Geology of Small Bodies |publisher=NASA |accessdate=15 August 2013}}</ref>
Sowat 6% van die asteroïdes naby die Aarde is vermoedelik uitgedoofde komeetkerns wat nie meer gas vrystel nie.<ref name=dormant>{{cite journal |doi=10.1016/j.icarus.2006.02.016 |arxiv=astro-ph/0603106v2.pdf |year=2006 |title=The size–frequency distribution of dormant Jupiter family comets |last1=Whitman |first1=K |last2=Morbidelli |first2=A |last3=Jedicke |first3=R |journal=Icarus |volume=183 |pages=101|bibcode = 2006Icar..183..101W }}</ref>
===Koma en stert===
| |||