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
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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
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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
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This Tweet was deleted by the Tweet author. Learn more
Betelgeuse is 50 milliarcseconds, the sun is about 0.5 degree, so about 36,000 times bigger in apparent disc size. Pluto from earth is about 4000 times bigger (0.06”). If I did my conversions right.
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Replying to @vgr
What’s that in radians I wonder?
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Not sure how these images are made, probably interferometric from earth mostly. JWST resolving power is 0.1 arc seconds so I guess not enough for stellar disks?
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Replying to
Deleted speculation on stellar disks. JWST is 0.1 arc seconds, stellar disks are in milliarcseconds, so a 100 times smaller. You need interferometric telescopes to even begin. Like the VLT in Chile
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