Human hair width: 70 microns
JWST observing band: 0.6 to 28 microns, ~0.1-0.5 hair width (2-10 waves/hair)
Visible spectrum = 0.4 to 0.7 microns, ~0.05-0.1 hair (10-20 waves/hair)
Hydrogen atom size = 1 angstrom = 10^-4 micron, = 700,000/hair
Just practicing fermi estimation
Conversation
If red wavelength were 1 inch the longest waves JWST observes would be about 4 feet
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I’m getting steadily more useless
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Afaict, the infrared bandwidth is being achieved purely through cooling. The mirror material/surface finish seems similar to optical telescopes.
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Human body heat is around 12 microns, right in the middle of JWST pass band. Clearly JWST is secretly a night vision spy cam 🤯
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C02 absorption is 15nm… it’s a climate change observatory!
Kidding aside, sadly JWST can’t look at earth at all since it is at L2 and looking at earth = looking at sun = too much heat = telescope is blinded. That huge heat shield is a bigger deal than the telescope itself.
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Here’s an interesting thing about the earth’s emission spectrum giss.nasa.gov/research/brief
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Here’s a gif of increasing absorption at 13-15 micron due to C02
Quote Tweet
This GIF took 3 years to make.
Python/Jupyter #dataviz of 17 years (1,400 GB) of
measurements, visualized in 17 seconds.
This is the first analysis of
outgoing IR declining at 13-15μm due to rising CO₂. Warming at 10-13μm is also evident.
GIF
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Ah here is an interesting explainer on interstellar dust absorption (1000 nm = 1 micron so this ranges from 0.4 to 0.8 micron, ie mostly visible blockage here… so looking through dust, at cooler objects than typical stars) spiff.rit.edu/classes/phys23

