Posted on 10/21/2017 2:32:42 PM PDT by BenLurkin
[P]revious estimates of the remaining NEAs have been plagued by a consequential round-off error that have skewed the results.
The source of this error has to do with... size-frequency distribution.
...
2015 study conducted by Harris and DAbramo which appeared in Icarus under the title The population of near-Earth asteroids yielded an estimate of 990 NEAs that were larger than 1 km in diameter. However, Tricarios study (The near-Earth asteroid population from two decades of observations, also published in Icarus), which was based on the opposite less than or equal to assumption, produced estimates that were 10% lower.
As Harris explained, this prompted DAdramo and him to considered a different approach. We corrected the problem for the current analysis by choosing bin boundaries at .05 magnitudes, e.g. 17.25 to 17.75, so the 0.1 round-off thresholds naturally put objects in the right bin, he said. When Tricarico and I each made these corrections, our population estimates fell into almost perfect agreement.
After applying the correction, Harris and DAbramos overall estimate of undiscovered NEAs dropped from 990 to 921 ± 20. Beyond allowing for consistency between different studies, these corrected estimates also reduced the total number of undiscovered objects that remain undiscovered. According to the latest tallies from NASAs Jet Propulsion Laboratory, 884 NEAs that are about 1 km in diameter have been discovered so far.
Based on the previous population estimate of 990 objects, this implied that the current surveys are 89% complete and 106 were yet to be found. When the corrections were applied to these numbers, JPLs surveys now appears to be 96% complete, and only 37 objects remain to be found (almost three times less). Naturally, these new estimates depends on their own sets of assumptions, and different results can be obtained based on different criteria.
(Excerpt) Read more at universetoday.com ...
True, but it's a pretty good indicator of rarity...
Just to be clear, what they are saying is:
The ones we dont know about are fewer than we thought.
(Is this a known unknown or an unknown known?)
Good work Ben! Now can you please do something about those giant black holes/neutron stars, etc.? I hear everybody yammering about them but I never see anyone doing anything about it. It’s a big problem and I’m really, really worried. Thanks.
Thank you, I'll be here all week. Don't forget to tip the waitress.
Naturally, these new estimates depends on their own sets of assumptions, and different results can be obtained based on different criteria.
So, there you have it, we’re all gonna die.
Not a worry, the GSV Sleeper Service (90 x 60 x 20 km) doing 230 kilolights/hour will be here before they become a problem - the SS is carrying a full complement of Abominator ROUs (rapid offensive units). The Zycathian Invasion Fleet doesn’t have a prayer.
You can’t see all those problematic black holes because they are black and because there is too much dark matter in the way ...
Did they take into account the ones the Bugs deflected towards the Earth. Get out of Buenos Aires NOW!
I don’t know.
230 kilolights/hour is above the speed limit.
Do they have those big subwoofers that shake everyones windows?
How about those fireballs they squeeze out of their rear ends?
One tried for a jetliner last night! Somebody made a mistake.
The sub woofers are included in the package - the are the same ones used by Disaster Area (the loudest rock band in the Galaxy, but in fact the loudest noise of any kind at all) before they all suffered a debilitating loss of coordination making it impossible to carry on so they put everything up for sale.
In case you are not aware, the ex-Disaster Area sub woofers in question will be located just outside of Mercury’s orbit; when they fire up you will still need very big earplugs.
231 kilolights/hour to be exact. There is no speed limit between the stars. Even super-lifters can’t keep up.
The Brain Bug that figured out the precise timing and impact point is one hell of a Mathematician, that's for sure. Can't imagine the numbers of Bean Burritos and gallons of Beer it must take to get those things going.
Math is a construct. It sometimes makes accurate predictions. However when you extrapolate too much on data that is iffy at best your predictions are worthless. Like this article.
Sponsoring FReepers are contributing
$10 Each time a New Monthly Donor signs up!
Get more bang for your FR buck!
Click Here To Sign Up Now!
Classic Oxymoron
That’s nice.
However, I saw a documentary recently where scientists theorize that for every planet that is in orbit, there are four that are rogue, just tooling around the universe.
One of those babies even comes into the solar system we are toast.
Hold on, you mean the Japanese Fleet could be rounding Diamond Head right now and we wouldn’t know anything about it?
The possibilities just have to exist. ;-D
If they're "undiscovered" then how do we know there are fewer of them?
The fact is, these are estimates. One of the ways Near-Earth Asteroids have been studied {ahem} has been to NOT search the skies for them, but rather to roll out some spiffy new computer program to estimate how many are out there. If the idea that *most* of the extinction level impacts were caused by NEAs (which seems likely enough) happens to be, y'know, *wrong*, and the far-out interlopers that no one is particularly interested in looking for caused those, and one is slated to cause the next big kaboom, well, nobody's right if everybody's wrong. Thanks BenLurkin.
|
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.