Published · 14h agoScience3 min read
NASA's two Sun papers ask paleoclimate to carry an astrophysical term
Simulations strand Earth outside the heliosphere three times in 14 million years, and dust in sediment cores agrees. The cadence, roughly one encounter every 4.5 million years, limits what it explains.
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What happened
- NASA's SHIELD center published simulations on Aug. 21 in Annual Review of Astronomy and Astrophysics that reverse-engineer the heliosphere's path through the Milky Way.
- Merav Opher's team found at least three encounters with interstellar cold clouds, around 2-3, 6-7 and 13-14 million years ago.
- Elements common in interstellar dust show up in deep-sea sediment cores, Antarctic snow and lunar samples dated to those same windows.
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Why it matters
- decisionReconstructions built from orbital change, greenhouse gases and ice now have to say whether they include a galactic-environment term or are assuming the heliosphere held constant.
- constraintA dust horizon records when Earth was exposed, not when it cooled, so promoting the match to attribution needs the two chronologies dated independently and tightly.
- capabilityA working digital twin of the heliosphere would let heliophysics hand Earth-system modellers a time-varying outer boundary condition instead of a fixed one.
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
In two recent NASA-funded studies, scientists examined how ancient events in the Sun's history may have helped create Earth's climate and driven previously unexplained climatic shifts.
ReportedView cited source - [2]
Researchers at NASA's SHIELD center published a paper on Aug. 21 in Annual Review of Astronomy and Astrophysics, using computer modeling to reverse-engineer the path of the heliosphere through the galaxy.
ReportedView cited source - [3]
Merav Opher, SHIELD's principal investigator at Boston University, and her team ran simulations showing the Sun encountered frigid expanses of gas and dust at least three different times in the past few million years.
ReportedView cited source - [4]
In those instances, massive interstellar cold clouds pushed against the heliosphere until it shrank to smaller than Earth's orbit, stranding the planet outside the Sun's protective shield.
ReportedView cited source - [5]
The exposures occurred approximately 2 to 3 million, 6 to 7 million, and 13 to 14 million years ago.
ReportedView cited source - [6]
The simulation results match geologic evidence: elements prevalent in interstellar dust appear in deep-sea sediment core samples, Antarctic snow, and lunar samples during those timelines.
ReportedView cited source
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