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Space Science

Video Showing Half a Million Asteroid Discoveries 154

Posted by CmdrTaco
from the final-frontier dept.
An anonymous reader writes "Since 1980 over a half million asteroids have been discovered, mostly between the orbits of Mars and Jupiter, now thanks to this video you can see this activity condensed into a few minutes. At full resolution it's a mesmerizing experience as new discoveries are added and the video makes it possible to see patterns in the discovery positions, for example a large number appear in line between Earth and Jupiter as astronomers started looking for smaller jovian moons after Voyagers visit to the system."

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Video Showing Half a Million Asteroid Discoveries

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  • Re:Needs a caption (Score:2, Informative)

    by michaelwv (1371157) on Thursday August 26, 2010 @10:31AM (#33381728)
    Discoveries are observations. Most discoveries are near opposition. It's only for special reasons that some surveys have been looking in other directions: either things like WISE that are in the infrared and so have special restrictions about where they can point, or targeted searches for near-Earth objects. In you click on the video you can read all about it in the caption. http://www.youtube.com/watch?v=S_d-gs0WoUw [youtube.com]
  • by mbone (558574) on Thursday August 26, 2010 @10:33AM (#33381754)

    There are no known Venus trojans, but they would be hard to detect from Earth. Messenger is looking for Mercury trojans, which should be dynamically stable (and even harder to detect from Earth). While the Earth has a handful of co-orbiting asteroids, I am not aware of any solidly confirmed Earth trojans. There are 4 known Mars trojans [wikipedia.org].

    None of these objects are of sufficient numbers to show in this video.

  • Re:Needs a caption (Score:2, Informative)

    by Anonymous Coward on Thursday August 26, 2010 @10:40AM (#33381830)

    View of the solar system showing the locations of all the asteroids starting in 1980, as asteroids are discovered they are added to the map and highlighted white so you can pick out the new ones.
    The final colour of an asteroids indicates how closely it comes to the inner solar system.
    Earth Crossers are Red
    Earth Approachers (Perihelion less than 1.3AU) are Yellow
    All Others are Green

    Notice now the pattern of discovery follows the Earth around its orbit, most discoveries are made in the region directly opposite the Sun. You'll also notice some clusters of discoveries on the line between Earth and Jupiter, these are the result of surveys looking for Jovian moons. Similar clusters of discoveries can be tied to the other outer planets, but those are not visible in this video.

    As the video moves into the mid 1990's we see much higher discovery rates as automated sky scanning systems come online. Most of the surveys are imaging the sky directly opposite the sun and you'll see a region of high discovery rates aligned in this manner.

    At the beginning of 2010 a new discovery pattern becomes evident, with discovery zones in a line perpendicular to the Sun-Earth vector. These new observations are the result of the WISE (Widefield Infrared Survey Explorer) which is a space mission that's tasked with imaging the entire sky in infrared wavelengths.

    Currently we have observed over half a million minor planets, and the discovery rates snow no sign that we're running out of undiscovered objects.

  • Re:Time (Score:5, Informative)

    by somersault (912633) on Thursday August 26, 2010 @10:47AM (#33381892) Homepage Journal

    Actually, you can't see that on the 4:3 cropped version linked into Slashdot, but if you go to the actual YouTube video [youtube.com] you can see the counters for the current year and the currently discovered number of asteroids.

  • Re:Needs a caption (Score:3, Informative)

    by jdgreen7 (524066) on Thursday August 26, 2010 @10:49AM (#33381910) Homepage

    Double-click on the video to reach the YouTube page. To the right of the summary (left of the number of views) is a down-chevron icon. Click on that for the full description.

    Or, just copy and paste that description here:

    View of the solar system showing the locations of all the asteroids starting in 1980, as asteroids are discovered they are added to the map and highlighted white so you can pick out the new ones. The final colour of an asteroids indicates how closely it comes to the inner solar system.

    Earth Crossers are Red

    Earth Approachers (Perihelion less than 1.3AU) are Yellow

    All Others are Green

    Notice now the pattern of discovery follows the Earth around its orbit, most discoveries are made in the region directly opposite the Sun. You'll also notice some clusters of discoveries on the line between Earth and Jupiter, these are the result of surveys looking for Jovian moons. Similar clusters of discoveries can be tied to the other outer planets, but those are not visible in this video.

    As the video moves into the mid 1990's we see much higher discovery rates as automated sky scanning systems come online. Most of the surveys are imaging the sky directly opposite the sun and you'll see a region of high discovery rates aligned in this manner.

    At the beginning of 2010 a new discovery pattern becomes evident, with discovery zones in a line perpendicular to the Sun-Earth vector. These new observations are the result of the WISE (Widefield Infrared Survey Explorer) which is a space mission that's tasked with imaging the entire sky in infrared wavelengths.

    Currently we have observed over half a million minor planets, and the discovery rates snow no sign that we're running out of undiscovered objects.

  • Re:Needs a caption (Score:4, Informative)

    by Chris Burke (6130) on Thursday August 26, 2010 @10:49AM (#33381916) Homepage

    Oh, and there is a difference between "smaller jovian moons" (which would all be indistinguishable from Jupiter on this scale) and the Trojan asteroids (which are all more or less at Jupiter's orbital radius, and a good 3-6 AU from Jupiter, not "between Earth and Jupiter." There have been a lot of Trojans found recently.

    Right, which is why one would expect that if astronomers were pointing their telescopes at Jupiter in order to find new Jovian moons, they'd be likely to find asteroids between earth and Jupiter in the main asteroid belt, which is what the summary says, and the video seems to bear it out.

  • by CheshireCatCO (185193) on Thursday August 26, 2010 @10:51AM (#33381938) Homepage

    In addition to what mbone said, it's also the case that the terrestrial planets should have a much more difficult time capturing asteroids into their trojan points thanks to their smaller masses (and therefore shallower potential wells for the asteroids to get captured into).

  • Re:Needs a caption (Score:4, Informative)

    by PatHMV (701344) <post@patrickmartin.com> on Thursday August 26, 2010 @11:16AM (#33382254) Homepage
    The green color for asteroids does NOT indicate that the orbit has been "confirmed." It indicates that the orbit never crosses or approaches the Earth's orbit. And the green color for the planets as well as some of the asteroids hardly causes real confusion in watching, as the planets have their orbits permanently displayed with circles.

    I think you need to watch the video again, in 1080p resolution. It DOES show plenty of Jupiter trojans, but they don't stand out as much because not as many of those individual objects have been formally observed and catalogued (a requirement to be displayed in this particular video).

    If you were reviewing this for publications, I hope you would read (and understand) the caption provided with it a bit more thoroughly, and watch the highest resolution version, before making your evaluation.
  • by $RANDOMLUSER (804576) on Thursday August 26, 2010 @11:27AM (#33382370)
    At 3:01, the data is from 2010, so it has to be preliminary data from WISE [wikipedia.org].
  • by spacemandave (1231398) on Thursday August 26, 2010 @11:33AM (#33382458)
    That comes from the WISE mission: http://wise.ssl.berkeley.edu/mission.html [berkeley.edu] WISE is a whole sky infrared survey that happens to pick up asteroids. The spacecraft spins to survey a complete arc of sky roughly perpendicular to the Sun direction.

    You'll also notice that during much of the 2000s, there is a gap in discoveries at about the 5 o'clock position. This corresponds to monsoon season in the southwest U.S. (roughly July to mid September). Most of the discovered asteroids in the past decade were made by the Catalina Sky Survey, based just outside of Tucson, AZ, and they generally don't bother observing during monsoon season because of the increase in cloud cover.
  • by spacemandave (1231398) on Thursday August 26, 2010 @11:39AM (#33382528)
    You'll also notice that the discovery rate seems to "pulsate" with a period of about 12 times per year (this is most obvious in the 2000s when the discovery rate was mostly uniform throughout the year). I'll leave it as an exercise to the reader to explain why that is (hint, skies need to be very dark to observe faint asteroids).
  • by szyzyg (7313) on Thursday August 26, 2010 @11:48AM (#33382614)

    I hadn't quite finished this, I wanted to record a voiceover, but a friend submitted it before I was ready.

    So essentially the video shows asteroids which are known, so in the early portions around 1980 we have less than 10,000 and by the start of this month we have over half a million. Asteroids are highlighted on discovery and within a second they fade to the colour appropriate to their orbit (Green, Yellow and Red), asteroids are usually observed intensely around discovery and once an orbit is determined observers can go back and follow up to refine the exact elements, I only show the discovery, not follow up measurements. This does mean that a number of the objects that are being plotted have orbits that may be so poorly determined that they are 'lost in space' because they were only observed for a short time and by the time people attempted to follow up they were lost.

    At the start of the videos, the 1980's, CCD's weren't used for astronomy, photographic plates were the primary technology for imaging the sky, furthermore, there were no digital systems for identifying asteroids on these plates, so while many asteroids were no doubt imaged they were generally not of interest to the observers who were probably taking nice pictures of nebula or other photogenic phenomena. Many of the discoveries in the 1980's were still made visually by minor planet hunters who knew what they were looking for. One of the earliest 'bursts' in the video is most likely related to observations of Jupiter searching for new moons around the giant planet, they'd look for objects moving on the plates and then make an orbit determination to see if it was a moon, it's waaaaay cooler to find a moon since they're a rarer commodity, but if you merely find an asteroid at least you get a chance to name it.

    By the time we get to the mid 1990's we start to see automated sky search programmes like LINEAR, LONEOS, Spacewatch and the Catalina Sky Survey and these are primarily searching for asteroids in opposition since they're closer to Earth and at peak brightness so you can see a discovery cluster radiating out from the Earth.

    In the last 8 months you see WISE which is a satellite performing a full sky survey in the Infrared, its scans the sky at 90 degrees to the sun, so its discovery pattern is very distinctive.

  • by spacemandave (1231398) on Thursday August 26, 2010 @12:33PM (#33383126)

    then why wouldn't it be 13 times per year?

    I would guess that some of the data is submitted monthly and the tracts show when the data was submitted, not necessarily observed. there's also a lot of big pulses early on, far larger than the overall rate would see to indicate as within the normal deviation of observation rate at that point. hence, the thought that it's mapping based on submission date and some are submitting bulk results on a monthly or quarterly basis.

    Well, to an astrophysicist "roughly 12 times" is equivalent to 13 times, but your point is taken. I've sat in with the Catalina guys (on a nearly full moon night, so they didn't discover anything while I was there), and they don't wait to submit data. They send candidate objects to a followup telescope to confirm the discovery, then publish any object with the Minor Planet Center as soon as they are confirmed. They need to act quickly, because orbit refinements often rely on followup observations (often by amateur astronomers), and many objects, especially Near Earth Asteroids, could be lost if they are not followed up quickly. The big pulses in the discovery rates at early times are because objects were only discovered in sensitive surveys that were not run very frequently (and before the mid 1990s usually relied on photographic plates). After about 1997 once LINEAR got going (and later Catalina and a couple others) asteroid surveys have more or less been continuous, with lulls arising due to full moon nights and the weather patterns of southern Arizona and New Mexcio.

  • by jeffmeden (135043) on Thursday August 26, 2010 @12:45PM (#33383314) Homepage Journal

    then why wouldn't it be 13 times per year?

    Because 12.3683 is closer (somewhat) to 12 than it is to 13?

    Hint: 12.3683 is the number of synodic months per year

  • Re:Needs a caption (Score:3, Informative)

    by camperdave (969942) on Thursday August 26, 2010 @12:49PM (#33383368) Journal
    so they see an asteroid, it pops up on the video and then continues in it's observed orbit. How is that observation not a discovery? What's the difference?

    A discovery is when it passes from unknown to known. Once you know the asteroid is there, you can't discover it anymore.

"Everything should be made as simple as possible, but not simpler." -- Albert Einstein

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