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B Are asteroids found by the light they reflect?

  1. Dec 20, 2016 #1


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    My guess is that asteroids are discovered by the sun light they reflect, is this correct? What if, hypothetically, an asteroid absorbed all the sunlight that impacted it, could it still easily be found from other methods?
  2. jcsd
  3. Dec 20, 2016 #2

    jim mcnamara

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    Answer: yes.

    If an asteroid had zero albedo, it would indeed be hard to detect. If it were really large, like a dwarf planet (e.g., Ceres) it might be detectable by the gravitational effect it has on neighboring visible objects.
  4. Dec 20, 2016 #3
    An asteroid with zero albedo should warm up by sunlight and emit thermal infrared.
    Is any asteroid seen in infrared even though not seen in visible?
  5. Dec 24, 2016 #4
  6. Dec 24, 2016 #5

    jim mcnamara

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    From the articles - it looks like the infared spectrum is used as a secondary tool, gathering information after identification.. So, it is possible to search for zero albedo objects. It does not appear to be first line now.
  7. Dec 25, 2016 #6
    I thought asteroids were found almost exclusively through infrared? In WISE, the I stands for infrared.
  8. Dec 25, 2016 #7


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    I thought they were found mostly by looking for reflected sunlight. Hmmm...
  9. Dec 25, 2016 #8


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    there is a real mix of visual optical, IR, and radar
  10. Dec 25, 2016 #9
    True, I should have mentioned that point in post #4. I usually have http://asteroidsathome.net/boinc/ running in the background on my computer, It's interesting to see what can be derived from studying the photometric data.
  11. Dec 30, 2016 #10
    https://www.nasa.gov/feature/jpl/nasas-neowise-mission-spies-one-comet-maybe-two :smile:

    Near-Earth objects (NEOs) absorb most of the light that falls on them and re-emit that energy at infrared wavelengths. This enables NEOWISE's infrared detectors to study both dark and light-colored NEOs with nearly equal clarity and sensitivity.

    "These are quite dark objects," said NEOWISE team member Joseph Masiero, "Think of new asphalt on streets; these objects would look like charcoal, or in some cases are even darker than that."

    NEOWISE data have been used to measure the size of each near-Earth object it observes. Thirty-one asteroids that NEOWISE has discovered pass within about 20 lunar distances from Earth's orbit, and 19 are more than 460 feet (140 meters) in size but reflect less than 10 percent of the sunlight that falls on them.
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