4 ms·

It's amazing that we could detect an object that cold, that small, at those distances. How does that work?

by eloff 6y ago

doctoboggan 6y ago
From my understanding they took 2 pictures of the same spot at different times and then had volunteers (“citizen scientists”) look at those pictures to see if anything moved. You can see some examples of the kinds of pictures in the paper linked in another comment above.
unzadunza 6y ago
I had to look it up, because I'm curious too. It looks like volunteers are given images from NASA's Wide-field Infrared Survey Explorer (WISE) telescope. The volunteers then just look for moving objects. https://www.zooniverse.org/projects/marckuchner/backyard-worlds-planet-9/about/research https://www.zooniverse.org/projects/marckuchner/backyard-wor...
- nitrogen 6y ago
  I was unable to find a table matching wavelengths to visible temperatures in a bit of searching. Closest I could find is the chromaticity diagram on Wikipedia's Black-body Radiation article, which puts 1000K around 0.7nm red light. The WISE article lists 22μm as its longest wavelength, though that might no longer be attainable since WISE is out of coolant. If one can find out what blackbody temperature has its peak at 22μm, then we could maybe see how close to the edge of WISE's temperature range the 400C (673K) and -10C (263K) dwarves are. https://en.m.wikipedia.org/wiki/Wide-field_Infrared_Survey_Explorer https://en.m.wikipedia.org/wiki/Wide-field_Infrared_Survey_E... ---- Edit: found it: https://commons.m.wikimedia.org/wiki/File:Blackbody_peak_wavelength_exitance_vs_temperature.svg https://commons.m.wikimedia.org/wiki/File:Blackbody_peak_wav... Looks like 20μm is a bit below 200K, so if I'm interpreting this right, WISE should have had no temperature-related problem (leaving aside brightness) spotting a -10C brown dwarf.
  - eloff 6y ago
    Wow, that's amazing that it can detect light from objects at 200K. That's about the temperature of dry ice.
    - Roboprog 6y ago
      For anyone missing how little radiation that is, radiation is proportional to the 4th power of the temperature in Kelvin. 200 K is a bit below (water) freezing. 400 K is just over boiling. The 400 K object emits 16 times (2 ^ 4) more radiation than the same object at 200 K.
asdasfasdfasdf 6y ago
Often it's only because they pass in front of objects that we can see.

It's amazing that we could detect an object that cold, that small, at those distances. How does that work?

by eloff 6y ago

It's amazing that we could detect an object that cold, that small, at those distances. How does that work?

From my understanding they took 2 pictures of the same spot at different times and then had volunteers (“citizen scientists”) look at those pictures to see if anything moved. You can see some examples of the kinds of pictures in the paper linked in another comment above.

unzadunza 6y ago

I had to look it up, because I'm curious too. It looks like volunteers are given images from NASA's Wide-field Infrared Survey Explorer (WISE) telescope. The volunteers then just look for moving objects. https://www.zooniverse.org/projects/marckuchner/backyard-worlds-planet-9/about/research https://www.zooniverse.org/projects/marckuchner/backyard-wor...

nitrogen 6y ago
I was unable to find a table matching wavelengths to visible temperatures in a bit of searching. Closest I could find is the chromaticity diagram on Wikipedia's Black-body Radiation article, which puts 1000K around 0.7nm red light. The WISE article lists 22μm as its longest wavelength, though that might no longer be attainable since WISE is out of coolant. If one can find out what blackbody temperature has its peak at 22μm, then we could maybe see how close to the edge of WISE's temperature range the 400C (673K) and -10C (263K) dwarves are. https://en.m.wikipedia.org/wiki/Wide-field_Infrared_Survey_Explorer https://en.m.wikipedia.org/wiki/Wide-field_Infrared_Survey_E... ---- Edit: found it: https://commons.m.wikimedia.org/wiki/File:Blackbody_peak_wavelength_exitance_vs_temperature.svg https://commons.m.wikimedia.org/wiki/File:Blackbody_peak_wav... Looks like 20μm is a bit below 200K, so if I'm interpreting this right, WISE should have had no temperature-related problem (leaving aside brightness) spotting a -10C brown dwarf.
- eloff 6y ago
  Wow, that's amazing that it can detect light from objects at 200K. That's about the temperature of dry ice.
  - Roboprog 6y ago
    For anyone missing how little radiation that is, radiation is proportional to the 4th power of the temperature in Kelvin. 200 K is a bit below (water) freezing. 400 K is just over boiling. The 400 K object emits 16 times (2 ^ 4) more radiation than the same object at 200 K.

asdasfasdfasdf 6y ago

Often it's only because they pass in front of objects that we can see.