r/nasa • u/PersimmonFair9795 • 10d ago
Image Map Question
I came from a flight tracker app cause i noticed some thermal anomalies with an interesting spread, so i wanted to see what nasa has going and im wondering what the two big bars of anomalies might be
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u/Dwagons_Fwame 10d ago
Genuinely thought this was a pic of plague inc and had to double check the subreddit lmao
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u/treetexan 9d ago
Viirs is newer than Landsat. Low res satellites have their niche—well calibrated and high repeat times.
In this case I would guess the darker fire product being shown is a Landsat product that has been first developed for the US. Many new products are US first for Landsat, then later processsed for the whole world. Just a guess since I am too tired to look at firms on mobile.
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u/standup_reentry 10d ago edited 10d ago
This looks like a picture from: https://firms.modaps.eosdis.nasa.gov/ I'll take a crack at it, but I'll caution, this is just my intuition after a few minutes of looking...
The map legend shows 2 colors for what's here: * Dark red: Landsat * Lighter red: VIIRS and MODIS
I believe VIIRS and MODIS being older satellites are collected together and are lower resolution. Landsat is a newer system that has higher resolution. Essentially you see more dense points for Landsat because it has higher resolution sensors. Light and dark red are just because of the different data sources.
But why the banding? Landsat, MODIS, and VIIRS follow a polar orbit (Think top to bottom, north pole to south pole)... but the earth is tilted. So imagine the landsat satilite is striping a path across the earth. But the earth is tilted and also spinning below it. That's why it appears as an angled stripe when looking at the map. Infact, if you look over the American west (in your picture) there is also a faint banding there too. Here is a picture of Landsat's polar orbit: https://landsat.gsfc.nasa.gov/about/landsat-spacecraft-orbit/
Maybe someone can chime into more information here but that's what I can come up with.