3 ms·

are there no tree fossils from that era that can show one part of the year being different from the rest? I remember reading that dinosaur meteorite was discov

are there no tree fossils from that era that can show one part of the year being different from the rest? I remember reading that dinosaur meteorite was discovered to have fallen in spring by those marks surely regular pattern of getting in-out of heliosphere be noticeable?

s1artibartfast 2y ago
>surely regular pattern of getting in-out of heliosphere be noticeable? Why do you say that? What would you look for?
- itishappy 2y ago
  Interstellar isotopes! > By studying geological radioisotopes on Earth, we can learn about the past of the heliosphere. Fe60 is predominantly produced in supernova explosions and becomes trapped in interstellar dust grains. Fe60 has a half-life of 2.6 Myr, and Pu244 has a half-life of 80.7 Myr. Fe60 is not naturally produced on Earth, and so its presence is an indicator of supernova explosions within the last few (~10) million years.
vlz 2y ago
Interesting question! From the Dendrochronology article on Wikipedia it seems we can at most go 14k years into the past with tree rings: > Bard et al write in 2023: "The oldest tree-ring series are known as floating since, while their constituent rings can be counted to create a relative internal chronology, they cannot be dendro-matched with the main Holocene absolute chronology. However, 14C analyses performed at high resolution on overlapped absolute and floating tree-rings series enable one to link them almost absolutely and hence to extend the calibration on annual tree rings until ≈13 900 cal yr BP." https://en.wikipedia.org/wiki/Dendrochronology?wprov=sfti1#Continuous_sequence https://en.wikipedia.org/wiki/Dendrochronology?wprov=sfti1#C... Interestingly it seems that tree ring chronologies can be mapped to increases in cosmic radiation named "Miyake events". https://en.wikipedia.org/wiki/Miyake_event https://en.wikipedia.org/wiki/Miyake_event

s1artibartfast 2y ago

>surely regular pattern of getting in-out of heliosphere be noticeable? Why do you say that? What would you look for?

itishappy 2y ago
Interstellar isotopes! > By studying geological radioisotopes on Earth, we can learn about the past of the heliosphere. Fe60 is predominantly produced in supernova explosions and becomes trapped in interstellar dust grains. Fe60 has a half-life of 2.6 Myr, and Pu244 has a half-life of 80.7 Myr. Fe60 is not naturally produced on Earth, and so its presence is an indicator of supernova explosions within the last few (~10) million years.

vlz 2y ago

Interesting question! From the Dendrochronology article on Wikipedia it seems we can at most go 14k years into the past with tree rings: > Bard et al write in 2023: "The oldest tree-ring series are known as floating since, while their constituent rings can be counted to create a relative internal chronology, they cannot be dendro-matched with the main Holocene absolute chronology. However, 14C analyses performed at high resolution on overlapped absolute and floating tree-rings series enable one to link them almost absolutely and hence to extend the calibration on annual tree rings until ≈13 900 cal yr BP." https://en.wikipedia.org/wiki/Dendrochronology?wprov=sfti1#Continuous_sequence https://en.wikipedia.org/wiki/Dendrochronology?wprov=sfti1#C... Interestingly it seems that tree ring chronologies can be mapped to increases in cosmic radiation named "Miyake events". https://en.wikipedia.org/wiki/Miyake_event https://en.wikipedia.org/wiki/Miyake_event