[IGPP Everyone] Astro colloquium today, May 10, 3:30pm: "The Sun’s Trajectory in the Last 10 Million years and possible terrestrial implications on Climate and Biological Evolution" by Merav Opher (BU)

[Emmanuel Masongsong]

Dear All, 


Please join us today, Wednesday, May 10, at 3:30 pm PDT, for an Astronomy colloquium, in PAB 1-434, by Merav Opher (BU), who will give a talk entitled " The Sun’s Trajectory in the Last 10 Million years and possible terrestrial implications on Climate and Biological Evolution ." See below for Merav's talk info. 

The talk will also be broadcast on zoom if you'd like to join that way: 
https://ucla.zoom.us/j/95210267106 

** Undergrads are welcome!** 

We will have pre-colloquium snacks at 3 pm on the patio. 

Hope to see you there, 
Smadar 





===================== 


Merav Opher (BU) 

Title: The Sun’s Trajectory in the Last 10 Million years and possible terrestrial implications on Climate and Biological Evolution 



Abstract: Until recently the primary focus with respect to astronomical impacts on Earth’s climate and biota have centered around those arising from changes in the tilt of the Earth axis, spin and rotation, which not only drive seasonal change but are also implicated in shifts between arid and wet climatic regimes over periods ≥ 10,000 years, due to changes in solar insolation. The Sun moves large distances (~19pc/Myr) through the quite variable Interstellar Medium. There is geological evidence from 60Fe and 244Pu isotopes that Earth received interstellar material about 2-3 Myr ago and 7 Myr ago. These isotopes were interpreted evidence for a nearby supernova, however that has been cast into doubt. In this talk I will discuss our new research indicating the encounter of Earth with massive cold cloud in Local Ribbon of Cold Clouds, 3 Myr ago and with the edge of the Local Bubble 7 Myr ago. Both encounters shrinked the Sun’s protective bubble—the heliosphere—to within Earth’s orbit exposing Earth to a cold dense interstellar medium. Such scenario should be discussed in context with other ones proposed to explain the cooling seen by Oxygen isotopes measured in deep sea Foraminifera. I will discuss the possible terrestrial consequences to climate and to biological evolution. The exposure to a cold dense interstellar medium has implications on climate and increase radiation. Increased radiation alone could have effects on climate, organismal mutation rates, aging, and extinction rates, and thus broad patterns of diversification. 








-- 


Prof. Smadar Naoz 
Department of Physics & Astronomy, UCLA 
http://www.astro.ucla.edu/~snaoz/ 


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