3 ms·

Well, it was small, but should have been spotted.

mitchty 10y ago
Spotted by what or who exactly? If we want to see asteroids we need satellites in orbit around the sun monitoring our blind spots (things coming at us from the sun). Until then we'll never be able to spot things in all circumstances. It also was spotted: A smallish asteroid zoomed past Earth this morning (Jan. 9), just two days after scientists first spotted the space rock. Even assuming we had perfect alerting and this was a problem, what action should have been taken considering this is a common occurrence?
- jessriedel 10y ago
  Asteroids are identified and tracked with radio waves, not visible light, so I don't think sun glare is a major issue.
  - sxcurry 10y ago
    I've never heard this before. Can you provide a reference for more info?
    - jessriedel 10y ago
      Radar is how lots of asteroid imaging is done: https://en.wikipedia.org/wiki/Radar_astronomy#Asteroids_and_comets https://en.wikipedia.org/wiki/Radar_astronomy#Asteroids_and_... However, I wasn't aware of the optical methods mitchty was referring to.
  - LeoPanthera 10y ago
    This is not correct. Optical telescopes are used, in conjunction with the WISE space telescope. https://www.nasa.gov/content/asteroid-grand-challenge/detect/how-do-we-detect-asteroids https://www.nasa.gov/content/asteroid-grand-challenge/detect...
  - CydeWeys 10y ago
    Active radar is subject to n^4 (!!!) drop-off with distance and as such is not useful for astronomical observation of any sort. Only passive detection is useful, which has a much more manageable dropoff of n^2. And asteroids don't emit radio waves, but they do reflect the Sun's light.
    - snrplfth 10y ago
      I think they're talking about the Goldstone Array: https://en.wikipedia.org/wiki/Goldstone_Solar_System_Radar https://en.wikipedia.org/wiki/Goldstone_Solar_System_Radar It's used for high-res imaging of asteroids that pass close by.
      - CydeWeys 10y ago
        Interesting, though it appears to be useful for imaging, not so much detection.
  - mitchty 10y ago
    Radio only works for relatively close asteroids. https://en.wikipedia.org/wiki/Sentinel_Space_Telescope https://en.wikipedia.org/wiki/Sentinel_Space_Telescope Which was sadly cancelled: http://www.dailymail.co.uk/sciencetech/article-3255059/Nasa-pulls-plug-killer-asteroid-hunter-Sentinel-mission-set-search-dangerous-space-rocks-loses-30-million-support.html http://www.dailymail.co.uk/sciencetech/article-3255059/Nasa-... But the principle was based off infrared: http://aviationweek.com/space/ball-aerospace-ramps-sentinel-asteroid-mission http://aviationweek.com/space/ball-aerospace-ramps-sentinel-... The canadian satellite also uses light: https://en.wikipedia.org/wiki/Near_Earth_Object_Surveillance_Satellite https://en.wikipedia.org/wiki/Near_Earth_Object_Surveillance... Visible light is only one fraction of the spectrum, infrared is far more valuable for detection. Most asteroids are detected via passive observation. Radio waves are not conducive to detecting asteroids.
    - jessriedel 10y ago
      My mistake. Thank you for the correction.

Spotted by what or who exactly? If we want to see asteroids we need satellites in orbit around the sun monitoring our blind spots (things coming at us from the sun). Until then we'll never be able to spot things in all circumstances. It also was spotted: A smallish asteroid zoomed past Earth this morning (Jan. 9), just two days after scientists first spotted the space rock. Even assuming we had perfect alerting and this was a problem, what action should have been taken considering this is a common occurrence?

jessriedel 10y ago
Asteroids are identified and tracked with radio waves, not visible light, so I don't think sun glare is a major issue.
- sxcurry 10y ago
  I've never heard this before. Can you provide a reference for more info?
  - jessriedel 10y ago
    Radar is how lots of asteroid imaging is done: https://en.wikipedia.org/wiki/Radar_astronomy#Asteroids_and_comets https://en.wikipedia.org/wiki/Radar_astronomy#Asteroids_and_... However, I wasn't aware of the optical methods mitchty was referring to.
- LeoPanthera 10y ago
  This is not correct. Optical telescopes are used, in conjunction with the WISE space telescope. https://www.nasa.gov/content/asteroid-grand-challenge/detect/how-do-we-detect-asteroids https://www.nasa.gov/content/asteroid-grand-challenge/detect...
- CydeWeys 10y ago
  Active radar is subject to n^4 (!!!) drop-off with distance and as such is not useful for astronomical observation of any sort. Only passive detection is useful, which has a much more manageable dropoff of n^2. And asteroids don't emit radio waves, but they do reflect the Sun's light.
  - snrplfth 10y ago
    I think they're talking about the Goldstone Array: https://en.wikipedia.org/wiki/Goldstone_Solar_System_Radar https://en.wikipedia.org/wiki/Goldstone_Solar_System_Radar It's used for high-res imaging of asteroids that pass close by.
    - CydeWeys 10y ago
      Interesting, though it appears to be useful for imaging, not so much detection.
- mitchty 10y ago
  Radio only works for relatively close asteroids. https://en.wikipedia.org/wiki/Sentinel_Space_Telescope https://en.wikipedia.org/wiki/Sentinel_Space_Telescope Which was sadly cancelled: http://www.dailymail.co.uk/sciencetech/article-3255059/Nasa-pulls-plug-killer-asteroid-hunter-Sentinel-mission-set-search-dangerous-space-rocks-loses-30-million-support.html http://www.dailymail.co.uk/sciencetech/article-3255059/Nasa-... But the principle was based off infrared: http://aviationweek.com/space/ball-aerospace-ramps-sentinel-asteroid-mission http://aviationweek.com/space/ball-aerospace-ramps-sentinel-... The canadian satellite also uses light: https://en.wikipedia.org/wiki/Near_Earth_Object_Surveillance_Satellite https://en.wikipedia.org/wiki/Near_Earth_Object_Surveillance... Visible light is only one fraction of the spectrum, infrared is far more valuable for detection. Most asteroids are detected via passive observation. Radio waves are not conducive to detecting asteroids.
  - jessriedel 10y ago
    My mistake. Thank you for the correction.