Comets fade even as deep in space as Saturn's orbit, scientists find

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When comets first appear near Earth, their bright tails of ionized gas stun observers, but on every subsequent return, they become dimmer.

Comets fade even as deep in space as Saturn's orbit, scientists find : Read more

 

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Reference paper, Comet fading begins beyond Saturn, https://www.science.org/doi/10.1126/sciadv.abm9130, 30-March-2022.

"Abstract The discovery probability of long-period comets (LPCs) passing near the Sun is highest during their first passage and then declines, or fades, during subsequent return passages. Comet fading is largely attributed to devolatilization and fragmentation via thermal processing within 2 to 3 astronomical unit (au) of the Sun (1 au being the Earth-Sun distance). Here, our numerical simulations show that comet-observing campaigns miss vast numbers of LPCs making returning passages through the Saturn region (near 10 au) because these comets fade during prior, even more distant passages exterior to Saturn and thus elude detection. Consequently, comet properties substantially evolve at solar distances much larger than previously considered, and this offers new insights into the physical and dynamical properties of LPCs, both near and far from Earth."

My observations. Various assumptions made in the modeling including the use of the Oort cloud to explain LPC origin and many perihelia passages.

"Without fading, the typical detected LPC spends ∼10 million years (Ma) with q < 20 au and undergoes over 50 passages inside 20 au during that time span."

My note. Comments like this may place an upper limit on LPC lifetimes near Saturn and beyond observed today, thus all LPC observations today are comets much younger than the postulated 4.56 billion years old solar system based upon Clair Patterson studies and radiometric ages used for meteorites today.