QUESTIONS: Comet 209P/LINEAR

many different sources | Feb 27, 2014 | Yosemitest

[Yosemitest]

John Bochanski wrote an article tilted
The Next New Meteor Shower,
Astronomers confirm that debris from Comet 209P/LINEAR should create a sky show on May 24, 2014
on November 12, 2013 that is one of the most detailed I've read so far.
Here are some excerpts from it.

"Most meteor showers ... occur when Earth plows into the debris trail left behind by a comet.
The comet throws this debris off as it’s heated by the Sun, but while all comets heat up as they enter the inner solar system, many do not have orbits that intersect with Earth’s.

... The tried-and-true list of showers might change soon, though.
As we noted in 2012, the comet 209P/LINEAR, which passed by the Sun in 2009, may produce a big meteor shower on May 24, 2014.

... Detailed calculations of its orbit indicated that in May 2014 the comet’s debris trails would pass extremely close to Earth
(about 0.0002 Earth-Sun distances, or within spitting distance of our planet’s outermost atmosphere).
These thousands of particles could burn up in Earth’s atmosphere as meteors when our planet plows through the debris field.

... Ye and Wiegert report in an upcoming Monthly Notices of the Royal Astronomical Society, the team’s calculations suggest that the comet has been producing relatively large particles (on the order of 1 mm), meaning that the upcoming meteor shower may be chock-full of bright meteors.

... With the low dust production, as well as the team’s lower estimate of how many debris streams from the comet's previous passes are hanging around in this region of space,
it’s highly unlikely that we’re in for a “meteor storm” (1,000 per hour) —
although the team couldn’t quite rule it out.

... It’ll be worth going out to look in May.
The meteor shower is set to peak around 7h Universal Time on May 24, 2014, with the radiant point (where the meteors appear to come from) in the constellation Camelopardalis.
That’ll be a fist-width or two above the horizon for those around latitude 40° N;
the shower should be easily visible from much of the Northern Hemisphere.

As Comet 209P/LINEAR enters the inner solar system again, it will brighten but still be relatively faint with an apparent magnitude of 11 around the time of the shower.
Nonetheless, skywatchers will have their telescopes trained on this comet, as new data on its position and brightness will be crucial for updating models of its behavior. ... "


Kelly Beatty wrote an article titled Meteor Storm Brewing for 2014 ? on October 9, 2012 and he stated:

" ... It follows a looping but relatively tight path that carries it just inside Earth's orbit every 5.04 years.
According to dynamicist Syuichi Nakano, Comet 209P/LINEAR's next perihelion occurs on May 6, 2014, at a point 0.969 astronomical unit from the Sun and with Earth not far away.

Just 18 days later, we should cross through dozens of particle streams shed during past orbits.
The predictions are still rough, but three different models suggest the sky show could be spectacular.
"All the trails ejected between 1803 and 1924 cross Earth's path in May 2014," notes Jérémie Vaubaillon (IMCEE, France).
"As a consequence, this shower might as well be a storm,"

... The best part of all this prognostication, at least from a U.S. perspective, is that the meteor display should peak between 7:00 and 8:00 Universal Time on May 24th — it'll be dark across virtually all of North America.
... And the Moon will be a narrow waning sliver just a few days from new. "

Mikhail Maslov wrote

" ...The Earth is expected to encounter a great number of the comet 209P trails in 2014.
The main source of activity should become 1898-1919 trails,
however some meteors could be produced by the earlier trails of the comet, down to 1763 trail, which is the oldest computed trail, and even earlier.
The computed time of maximum activity is May 24, 2014, at 7:21 UT,
theoretical radiant is RA=122.8�, Dec=+79.0�.
It is difficult to estimate expected intensity of the outburst due to the lack of past observed cases of activity from the given comet meteor shower,
as well as due to very small size of the comet itself and unknown level of its past activity.
However, considering high computed density and high number of encountered trails, we can very approximately estimate ZHRex as 100 meteors.
Its a very cautious estimation, and it is very possible that real activity will turn to be much higher.
Storm levels are also far from being excluded.


Also take a look at the 3D view of the 1903 meteoroid trail in the Solar system of comet 209P/LINEAR (2004 CB) :



And the Equivalent 2D view (XY).








So my first question is:

What does this Noeds-Earth2014.jpg , or the 3D model above, actually tell us?




I assume this is a 3-dimensional chart, and we can't tell the 2 dimensional danger it represents to us.

Are there any Radar Images of Comet 209P/Linear or Hubble photos of it showing its core?

[Errant]

I wonder if a coma impact could cause a disturbance in the orbit of its moons?

Name and pronunciation			Image	Diameter (km)	Mass (kg)	Semi-major axis (km)	Orbital period (h)	Average moonrise period (h, d)
Mars I	Phobos	/ˈfoʊbəs/ FOE-bəs		22.2 km (13.8 mi) (27×21.6×18.8) km	10.8×1015	9,377 km (5,827 mi)	7.66	11.12 h (0.463 d)
Mars II	Deimos	/ˈdaɪməs/ DYE-məs		12.6 km (7.8 mi) (10×12×16) km	2×1015	23,460 km (14,580 mi)	30.35	131 h (5.44 d)
The relative sizes of and distance between Mars, Phobos, and Deimos, to scale. (Load the image in full size to see both Moons of Mars.)

[Errant]

Do you see what I mean? The "spitting distance" remark is very misleading and unhelpful to the understanding of what's supposed to be happening.

Yep, it's misleading. The satellite images I've seen suggest a mass of debris flying in a large formation, instead of single body comet. If the supposed radar returns we see on the net are true, then outside the main body of debris are numerous other objects spread out over very large distances.

[Errant]

Also take a look at Torricelli.

It would be interesting to plot out the "gravel deposits" to see if they're eccentric and aligned in the same direction.

[Yosemitest]

I think the "ET meteorite/comet impacting the glacier ice" theory would explain the "gravel deposits".
Read Interpreting Carolina Bays as Glacier Ice impacts Antonio Zamora.

[Yosemitest]

"The "spitting distance" remark is very misleading and unhelpful to the understanding of what's supposed to be happening."

I agree.

Have you seen the graphic or a chart that starts about 28 seconds into the video referenced in comment #7 ?
I'm trying to find the original source to read it, and do more research on it.

[Yosemitest]

You might want to look at the Oblique Impact Crater on Mars with ejecta butterfly.

Look at the overlay of that crater on the Saginaw Region.

[txhurl]

bttt

[Yosemitest]

Case Closed? Comet Crash Killed Ice Age Beasts

"A space rock crashed into Earth about 12,900 years ago, wiping out some of North America's biggest beasts and ushering in a period of extreme cooling, researchers say, based on new evidence supporting this comet-crash scenario.

If such an impact took place, it did not leave behind any obvious clues like a crater. But microscopic melted rock formations called spherules and nano-size diamonds in ancient soil layers could be telltale signs of a big collision. The mix of particles could only have formed under extreme temperatures, created by a comet or asteroid impact.


Spherules from archaeological sites in the study.
The microscopic particles have marred surface patterns from being crystallized in a molten state and then rapidly cooled.
Researchers first reported in 2007 that these particles were found at several archaeological sites in layers of sediment 12,900 years old. Now an independent study published in the Sept.17 issue of the Proceedings of the National Academy of Sciences (PNAS) says those findings hold up.

A team led by Malcolm LeCompte, of Elizabeth City State University in North Carolina, studied sediment samples from three sites in the Unites States: Blackwater Draw in New Mexico, Topper in South Carolina, and Paw Paw Cove in Maryland. The researchers said they found the same microscopic spherules in some of the same ancient layers as were found in the 2007 study.

A comet crash in the ice fields of eastern Canada could explain the region's die-off during the late Pleistocene epoch. While the cause of the catastrophic extinction event has been debated, researchers say it killed off three-fourths of North America's large ice-age animals, such as saber-toothed tigers and woolly mammoths, and the Clovis people, a Stone Age group that had only recently immigrated to the continent. ... "

[Errant]

Case Closed?

Thanks for the link. Wouldn't surprise me. As for the "gravel deposits", they seem to fit the time frame as the top of most deposits begin just under the surface.

Pretty much the same depth at which the artifacts of native Americans can be found.

[dr_lew]

I hadn't seen it, but this is how I interpret what I see in the freeze frame.

The color code is showing a "fluence" in units of particles per 10^10 km^2, which of course is particles per unit area. To make sense of this you need motion perpendicular to the area so that km/sec * particles/km^3 = particles/km^2 /sec . Hmmmm. Well a search on "209P fluence" gave me a pdf with this exact figure. How about them apples! The caption to it reads:

Figure 2. The footprint of the meteoroid stream from 209P/LINEAR projected on the ecliptic. The colour scheme labels the free space (no gravitational focusing) fluence of particles through a plane perpendicular to the stream’s arrival direction. Locations of the Earth at particular times are labeled with arrows. The Sun is to the upper right.

Well, Hmmmm again. There's no time unit. But ah, there is! Another search says "fluence" is a "flux integrated over time" ... and the chart is labeled "fluence ... within +/- 7.0 days ... " So that means an integrated flux over 14 days, or an AVERAGE flux of this fluence/14 days. Much of a muchness.

So we're looking at ( for orange ) about 10^8 particles per 10^10 km^2/14 days . Now this is the flux of the stream in the solar frame of reference, ignoring the motion of the earth, which is ( presumably ) assumed to be sampling this flux at a slower speed.

Well, 10^10 km^2 is (10^5 km)^2 or roughly the "footprint" of the earth. So we're talking about 10^8/14 particles/day or 10^8/14/24 ~= 300000 particles per hour entering the earth's atmosphere, at peak.

This is how I see it, but I've been known to be wrong. Anyway, this is my idea of a fun time, so thanks for asking!

These are tiny particles, and you'd have to guess what fraction of them would be observable from a given location. If this is 1/1000 then you'd have 300/hour or 5/minute of those tiny little streaks, assuming a dark sky. This is a lot as meteor showers go, and with a lot of little ones, you're going to see some big ones, so we'll see.

[dr_lew]

Well, 10^10 km^2 is (10^5 km)^2 or roughly the "footprint" of the earth. So we're talking about 10^8/14 particles/day or 10^8/14/24 ~= 300000 particles per hour entering the earth's atmosphere, at peak.

Ooops. The earth is roughly (10^4 km)^2, so the flux hitting the earth is 1/100 this, or ~3000 particles/hour ... again, of course, according to my reading.

[Errant]

~= 300000 particles per hour entering the earth's atmosphere, at peak.

That's not the 'peak' though, is it. Your calculations give an average over a certain number of days?

[Yosemitest]

Thanks.
If I can boil your comment down to simpler terms, you think

the math indicates those particles are almost all dust.
But with that much dust being around in those orbital paths
of 1898-1919 trails, however some meteors could be produced by the earlier trails of the comet, down to 1763 trail, which is the oldest computed trail, and even earlier,
that there is a small probability that there may be a few larger meteors in that cloud.

What are the chances of some of them being large enough to strike the ground, and cause some real damage ?

My guess is ~ nobody knows for certain.

[Yosemitest]

Check out this data from Kasuo Kinoshita, http://jcometobs.web.fc2.com/ [Orbital elements of the comet 209P LINEAR].
The numbers are beyond my comprehension, but you might can use them.

[Errant]

the math indicates those particles are almost all dust.

I've seen several reports talking about this comet being older or having made enough passes that much of the smaller particles have been blown away by the solar wind. If true, the remaining particles should be larger than a 'new' comet's average dust particle size?

[dr_lew]

My guess is ~ nobody knows for certain.

Sure, but it seems like the big ones are not associated with meteor showers produced by comet trails. Plus they're very rare, so the money's on the scoffers side.

These people are under continual disquietudes, never enjoying a minutes peace of mind; and their disturbances proceed from causes which very little affect the rest of mortals. Their apprehensions arise from several changes they dread in the celestial bodies: for instance, that the earth, by the continual approaches of the sun towards it, must, in course of time, be absorbed, or swallowed up; that the face of the sun, will, by degrees, be encrusted with its own effluvia, and give no more light to the world; that the earth very narrowly escaped a brush from the tail of the last comet, which would have infallibly reduced it to ashes; and that the next, which they have calculated for one-and-thirty years hence, will probably destroy us.

- Gulliver's Travels

[Yosemitest]

I understand what you're suggesting but read Mikhail Maslov's Introducton to meteor activity forecasting

" The overwhelming majority of meteor activity outbursts is traced with the modelling very good.
Particles ejected by the comet form lengthy trails.
One of the reasons is radiation pressure force, which acts parallel with gravitational force.
The latter is dependent on a particle mass,
i.e. it is proportional to the third power of particle radius.
The outcrying radiation pressuse is defined by the second power of particle radius.
So far the influence of radiation pressure is the more the less is size of a particle.
Its action is equivalent to the diminishing of gravitational constant G.
So it increases the orbital period of particles,
and the tinier a particle is,
the more it is continuously retarded from larger particles after their ejection from the comet.
This process therefore leads to the formation of lengthy comet trails.
Meteor modelling is done through computation of orbital evolution of particles ejected by the comet
with different velocities in directions tangential to the comet trajectory at the moment of perihelion.
In the reality, of course, particles are ejected not only at the point of perihelion,
but also during several months around it.
However, comets are in perihelion part of their orbits during quite a little time comparing to their overall orbital period
and main perturbations happen around their aphelions,
so when comets are closer to the Sun
newly ejected particles are moving very close to them in a compact dust cloud.
This is the reason we can take that cloud as completely ejected at the point of perihelion,
it doesn't virtualy influence the results of computations.

Speaking of directions in which particles are ejected
we can say that, again, in the reality they are ejected far
not only in tangential directions, but in all possible ones.
However, ejection velocities
(from 0 to 100 m/s, and the overwhelming majority of real ejections - from 0 to 20 m/s)
are negligibly small comparing to the own comet velocity (from 30 to 40 km/s) near the Earth's orbit),
ejected particles have only slightly changed orbits and don't "fly away in all directions".
Radial part of ejection velocity defines only thickness of a trail,
which usually reaches several hundreds thousands kilometers.
The shape of the trail is defined by tangential part of ejection velocity.

And the last. Non-gravitational forces are often not taken into consideration in meteor calculations, as is in our case.
However, some of them, say, radiation pressure, can be considered indirectly.
As far as this kind of force works as diminishing of gravitational constant G, this is equivalent to increase of ejection velocity
which could be easily accounted in the model.
So this non-gravitational force, as many others, doesn't change the configuration of trails,
but leads to shifting of particles with different masses along them.

As spoken previously, meteor trails modelling allowed to prepare very good predictions of shower activity in the previous years.
More serious problem is prediction of outburst intensity -
how strong the maximum could be.
For such predictions, special empirical models were elaborated
(the single possible way in this case)
but as before, for their improvement, new observations are very necessary. "

[Yosemitest]

"... it seems like the big ones are not associated with meteor showers produced by comet trails.
Plus they're very rare, so the money's on the scoffers side."

Thanks, that reduces the chances of a damaging strike.
But it doesn't wipe them out.
So the risk still stands.

[dr_lew]

The numbers are beyond my comprehension, but you might can use them.

As you say, these are orbital elements, i.e. each row gives the parameters for an ideal elliptical orbit which describes the current motion of the object.

The format is explained at his My elements format link. Not many have use for these, and I am not in that number, although I have gone there.

[dr_lew]

Nowadays Laputa holds sway over the whole globe.