[Deepwater6]

The ABC article below really doesn't let on as to how long scientist have known about this NEO. Was it common knowledge that it was coming well in advance or did we recently discover it? It tells of the next one they know of in 2028, but of course they don't know where they all are.

Also would anyone know of a website that can simulate known trajectories of past/current/future NEO's in relation to Earth? Or a site that overlays these paths in still form. At least the ones we know of course. thx


http://www.space.com...2011-sf108.html

http://abcnews.go.co...ory?id=14865802

[Qfwfq]

Deepwater6, on 04 November 2011 - 07:35 AM, said:

The ABC article below really doesn't let on as to how long scientist have known about this NEO.

Since it is called 2005 YU55 it must have been discovered in the year 2005, after that they must have been tracking it with increasingly precise predictions of its trajectory.

[Deepwater6]

That makes sense Qfwfq, but in the case of something like Shoemaker-levy-9. I have never heard a date attached to it though maybe it's official name has one. Is the discovery date always part of every objects description? Also what does the YU55 designate?

[JMJones0424]

I certainly don't know for a fact, but out of curiosity I dug around a bit and found this:
http://en.wikipedia....on_in_astronomy

Evidently, 2005 YU55 was the 1395th "minor planet" discovered between Dec 16th and Dec 31st 2005.

Also, from here:
http://en.wikipedia....ventions#Comets

"The famous Comet Shoemaker-Levy 9 was the ninth periodic comet jointly discovered by Carolyn Shoemaker, Eugene Shoemaker, and David Levy (the Shoemaker-Levy team has also discovered four non-periodic comets interspersed with the periodic ones), but its systematic name is D/1993 F2 (it was discovered in 1993 and the prefix "D/" is applied, since it was observed to crash into Jupiter)."

[Turtle]

Deepwater6, on 04 November 2011 - 07:35 AM, said:

...Also would anyone know of a website that can simulate known trajectories of past/current/future NEO's in relation to Earth? Or a site that overlays these paths in still form. At least the ones we know of course. thx

if you go to spaceweather.com & scroll down, there is a box headed "Recent & Upcoming Earth-asteroid encounters:". clicking on any NEO designation brings up a data page and an interactive java applet that lets you view the trajectory. i don't see there right away any means to search other dates however.
Spaceweather.com

here's another source that may help with some plots:
IAU Minor Planet Center

Deepwater6, on 04 November 2011 - 10:21 AM, said:

That makes sense Qfwfq, but in the case of something like Shoemaker-levy-9. I have never heard a date attached to it though maybe it's official name has one. Is the discovery date always part of every objects description? Also what does the YU55 designate?

on the shoemaker-levy-9, i suspect it's treated differently because it's not an NEO. anyway, here's the low-down on the lettering scheme following an NEO's year of discovery. duck & cover!!

Provisional designation in astronomy

wiki said:

...
The first element in a minor planet's provisional designation is the year of discovery, followed by two letters and, optionally, a number.

The first letter indicates the half-month of the object's discovery within that year —"A" denotes discovery in the first half of January, "D" is for the second half of February, "J" is for the first half of May ("I" is not used), and so on until "Y" for the second half of December. The first half is always the 1st through the 15th of the month, regardless of the numbers of days in the second "half".

The second letter and the number indicate the order or discovery within that half-month. The 8th minor planet discovered in the second half of March 1950, for example, would be provisionally designated 1950 FH. But since modern techniques typically yield far more than 25 objects (again, "I" is not used) in a half-month, a subscript number is appended to indicate the number of times that the letters have cycled through. Thus, the 28th asteroid discovered in the second half of March 1950 would be 1950 FC1. For technical reasons, such as ASCII limitations, the subscript is sometimes "flattened out", so that this could be written 1950 FC1. The subscripts were first used with 1926 GA1.

An idiosyncrasy of this system is that the second letter is listed before the number, even though the second letter is considered "least-significant". This is in contrast to most of the world's numbering systems. ...

[Deepwater6]

Thanks for the digging JMJones0424.

Turtle, Thanks for the websites....I think, wow a lot of information in there if you care to keep drilling. Me and the dog spent an hour and half looking through the one site. Goooood stuff.

A little off topic, but wanted to pass it on. The Nat Geo article below is about how the Taurid Meteor shower is peaking over this weekend. Here on the right coast it's not too hot or too cold, good weather for spotting shooters If the clouds cooperate.


http://news.national...-space-science/

[Turtle]

Deepwater6, on 05 November 2011 - 05:59 PM, said:

Thanks for the digging JMJones0424.

Turtle, Thanks for the websites....I think, wow a lot of information in there if you care to keep drilling. Me and the dog spent an hour and half looking through the one site. Goooood stuff.

A little off topic, but wanted to pass it on. The Nat Geo article below is about how the Taurid Meteor shower is peaking over this weekend. Here on the right coast it's not too hot or too cold, good weather for spotting shooters If the clouds cooperate.


http://news.national...-space-science/

so how did your taurid viewing go? cloudy skies for me here i'm afraid.

so the big rock missed us -again- and we can expect some new radar images soon. found a little video from nasa that sets the stage for 2005YU55.

video:
Scientists will be tracking an asteroid the size of an aircraft carrier as it flies by Earth on Nov. 8, 2011.


ps here's a fun calculator for what you would experience if this thing had hit us. you can vary the parameters as you like. here's my run for one situation for 2005YU55. :bomb:

main page:
earth impacts effects program

my simulation:
earth impacts effects program

Robert Marcus, H. Jay Melosh, and Gareth Collins said:

Please note: the results below are estimates based on current (limited) understanding of the impact process and come with large uncertainties; they should be used with caution, particularly in the case of peculiar input parameters. All values are given to three significant figures but this does not reflect the precision of the estimate. For more information about the uncertainty associated with our calculations and a full discussion of this program, please refer to this article

Your Inputs:
Distance from Impact: 161.00 km ( = 100.00 miles )
Projectile diameter: 400.00 meters ( = 1310.00 feet )
Projectile Density: 3000 kg/m3
Impact Velocity: 25.00 km per second ( = 15.50 miles per second )
Impact Angle: 45 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock

Energy:
Energy before atmospheric entry: 3.14 x 1019 Joules = 7.50 x 103 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 1.1 x 105years
Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).
The impact does not shift the Earth's orbit noticeably.

Atmospheric Entry:
The projectile begins to breakup at an altitude of 60200 meters = 198000 ft
The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 24.3 km/s = 15.1 miles/s
The impact energy is 2.97 x 1019 Joules = 7.09 x 103MegaTons.
The broken projectile fragments strike the ground in an ellipse of dimension 0.986 km by 0.697 km

Crater Dimensions:
Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.

Transient Crater Diameter: 6.06 km ( = 3.76 miles )
Transient Crater Depth: 2.14 km ( = 1.33 miles )

Final Crater Diameter: 7.7 km ( = 4.78 miles )
Final Crater Depth: 547 meters ( = 1790 feet )
The crater formed is a complex crater.
The volume of the target melted or vaporized is 0.187 km3 = 0.0448 miles3
Roughly half the melt remains in the crater, where its average thickness is 6.48 meters ( = 21.3 feet ).

Thermal Radiation:
Time for maximum radiation: 255 milliseconds after impact

Visible fireball radius: 4.16 km ( = 2.58 miles )
The fireball appears 5.87 times larger than the sun
Thermal Exposure: 3.22 x 105 Joules/m2
Duration of Irradiation: 1.34 minutes
Radiant flux (relative to the sun): 4

Seismic Effects:
The major seismic shaking will arrive approximately 32.2 seconds after impact.
Richter Scale Magnitude: 7.2
Mercalli Scale Intensity at a distance of 161 km:

VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.

VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

Ejecta:
The ejecta will arrive approximately 3.07 minutes after the impact.
At your position there is a fine dusting of ejecta with occasional larger fragments
Average Ejecta Thickness: 2.88 mm ( = 1.14 tenths of an inch )
Mean Fragment Diameter: 1.37 cm ( = 0.538 inches )

Air Blast:
The air blast will arrive approximately 8.13 minutes after impact.
Peak Overpressure: 11400 Pa = 0.114 bars = 1.62 psi
Max wind velocity: 25.6 m/s = 57.3 mph
Sound Intensity: 81 dB (Loud as heavy traffic)
Damage Description:


Glass windows will shatter.

[Turtle]

first new movie from nasa of 2005TU55.

2005TU55 radar movie

[Deepwater6]

Under "Robert Marcus" section, atmospheric entry. It says projectile begins to break-up. Can they tell which ones are going to hold (for the most part) to the ground, and which ones will explode in the air like the one in Siberia? Did you see anything on an estimated age for the object or would they need a sample for that?

Yes Taurid viewing went well. Didn't see any shooters, but an hour in the hot tub looking at stars beats watching my Eagles lose.

[Turtle]

Deepwater6, on 09 November 2011 - 08:05 AM, said:

Under "Robert Marcus" section, atmospheric entry. It says projectile begins to break-up. Can they tell which ones are going to hold (for the most part) to the ground, and which ones will explode in the air like the one in Siberia? Did you see anything on an estimated age for the object or would they need a sample for that?

Yes Taurid viewing went well. Didn't see any shooters, but an hour in the hot tub looking at stars beats watching my Eagles lose.

hot tub!! i knew i was forgetting something.

so on the breakup. yes they can tell pretty much about the breakup. note that the tunguska event is thought to have been a comet & not an asteroid. main factors affecting breakup include the type of material -ice, porous rock, dense rock, & iron for this program-, as well as the velocity, size (surface area & mass) and angle of entry. (the lower the angle the longer the traverse in the atmosphere.)

i guessed at the velocity and density of 2005TU55 for my simulation as i couldn't find those specifics. there is a pdf document from the authors that details the assumptions & methods used in the calculations. >>

Earth Impact Effects Program: A Web-based computer program for calculating the regional environmental consequences of a meteoroid impact on Earth (boldenation mine.)

Quote

Abstract–We have developed a Web-based program for quickly estimating the regional
environmental consequences of a comet or asteroid impact on Earth (www.lpl.arizona.edu/
impacteffects). This paper details the observations, assumptions and equations upon which the
program is based. It describes our approach to quantifying the principal impact processes that might
affect the people, buildings, and landscape in the vicinity of an impact event and discusses the
uncertainty in our predictions. The program requires six inputs: impactor diameter, impactor density,
impact velocity before atmospheric entry, impact angle, the distance from the impact at which the
environmental effects are to be calculated, and the target type (sedimentary rock, crystalline rock, or
a water layer above rock). The program includes novel algorithms for estimating the fate of the
impactor during atmospheric traverse, the thermal radiation emitted by the impact-generated vapor
plume (fireball), and the intensity of seismic shaking. ...

[Deepwater6]

Leonid meteor shower tonight and tomorrow night from midnight to 3am. Get out there and witness your cosmos in action.




http://abcnews.go.co...ory?id=14976359