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Beer w/Straw
2009-Dec-15, 12:54 AM
Quick question.

If it hit the Earth instead of Jupiter, would it have been extinction like the dinosaurs or, would it have completely destroyed the Earthe

publiusr
2009-Dec-15, 01:40 AM
The object could not blow up the planet, but could really hurt the biosphere.

astromark
2009-Dec-15, 09:38 AM
Earth would not be destroyed by such a low mass object. The fact that it broke into many fragments could have lessoned the impact and damage on humanities environment. I do not have the actual information before me as to size, number and velocity of the Shoemaker-Levy 9 comet.
Yes some considerable damage would have accured... thousands of lives lost and, possibly a long term winter from atmospheric debris... Ugly... or some degree less.
Damage to our Biosphere is bad stuff... What we need to concentrate on is learning how to find such Earth crossing objects and calculating methods of lessoning the risk. Big Budgets, and Deep pockets.. You could worry to much about this stuff...

Mark in clear Wanganui.

Beer w/Straw
2009-Dec-17, 03:43 PM
The fact that it broke into many fragments could have lessoned the impact and damage on humanities environment.

I thought it was Jupiters gravity that broke the comet apart, Earth not having rnough, it wouldn't.

chornedsnorkack
2009-Dec-17, 04:23 PM
I thought it was Jupiters gravity that broke the comet apart, Earth not having rnough, it wouldn't.

To the contrary. Earth is denser, therefore more capable of breaking comets apart.

Beer w/Straw
2009-Dec-17, 05:15 PM
Can you provide calculations?

cjameshuff
2009-Dec-17, 06:54 PM
Can you provide calculations?

Tidal force is proportional to mass and inversely proportional to distance cubed. Specifically, F = 2*deltar*G*m/r^3, where deltar is the radius of the body the tidal force is being measured on, m is the mass of the source of the tidal force, and r is the center-to-center distance between the two.

Jupiter is 317.8 Earth masses, and about 11 Earth radii. Everything else cancels out. Tidal force at Earth's surface is 11^3/317.8 = 4.2 times that on Jupiter's "surface".

Jupiter's bigger and a lot more massive, though. Tidal force will be greater for Jupiter at larger distances...at 1 Earth radius from Earth's surface, Earth's tidal force will only be 2/3 that of Jupiter's at the same distance. At 2 Earth radii, a bit over 1/4. Earth will break up objects that Jupiter couldn't, but it might not be able to break them up at a large enough distance to matter.

Tidal force as a function of distance to the surface of Earth (black) and Jupiter (red), horizontal units being Earth radii, vertical units being the tidal force at Earth's surface:
http://arklyffe.com/graph.html?x=-0.5,6&y=-0.1,1.5&xg=1,5,2&yg=1,5,2&fn0=1LcubExH1F&fn1=317LcubExH11F

(note: JavaScript graph using the <canvas> tag. Won't work in Internet Exploder.)

Cougar
2009-Dec-18, 02:58 AM
Can you provide calculations?

Wow, ask and ye shall receive! Good info, CJ.

Back to the initial question. According to this Earth Impact Calculator (http://www.lpl.arizona.edu/impacteffects/cgi-bin/crater.cgi?dist=20&diam=5&pdens=8000&pdens_select=0&vel=size%3D10&theta=30&tdens=2500&tdens_select=0):


If you are at a Distance from Impact: 500.00 km = 310.50 miles
and if the following parameters are accurate...
Projectile Diameter: 2000.00 m = 6560.00 ft = 1.24 miles (roughly the largest fragment of Shoemaker-Levy 9)
Projectile Density: 1000 kg/m^3
Impact Velocity: 48.00 km/s = 29.81 miles/s
Impact Angle: 60 degrees
Target Density: 2500 kg/m^3
Target Type: Sedimentary Rock

Energy:
Energy before atmospheric entry: 4.83 x 1021 Joules = 1.15 x 10^6 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 5.1 x 10^6years

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 Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
Transient Crater Diameter: 21.2 km = 13.2 miles
Transient Crater Depth: 7.5 km = 4.66 miles

Final Crater Diameter: 31.7 km = 19.7 miles
Final Crater Depth: 0.838 km = 0.52 miles

The crater formed is a complex crater.
The volume of the target melted or vaporized is 36.6 km^3 = 8.79 miles^3
Roughly half the melt remains in the crater, where its average thickness is 104 meters = 340 feet

Thermal Radiation:
Time for maximum radiation: 0.706 seconds after impact

Visible fireball radius: 14 km = 8.7 miles
The fireball appears 6.37 times larger than the sun
Thermal Exposure: 2.74 x 106 Joules/m^2
Duration of Irradiation: 437 seconds
Radiant flux (relative to the sun): 6.27

Effects of Thermal Radiation:

Much of the body suffers second degree burns

Deciduous trees ignite


Seismic Effects:

The major seismic shaking will arrive at approximately 100 seconds.
Richter Scale Magnitude: 8.7
Mercalli Scale Intensity at a distance of 500 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 334 seconds after the impact.
Average Ejecta Thickness: 1.45 cm = 0.569 inches
Mean Fragment Diameter: 2.91 mm = 0.115 inches


Air Blast:
The air blast will arrive at approximately 1520 seconds.
Peak Overpressure: 29100 Pa = 0.291 bars = 4.13 psi
Max wind velocity: 61.3 m/s = 137 mph
Sound Intensity: 89 dB (Loud as heavy traffic)

Damage Description:

Wood frame buildings will almost completely collapse.

Glass windows will shatter.

About 30 percent of trees blown down; remainder have some branches and leaves blown off.

danscope
2009-Dec-18, 04:13 AM
Not a good day on earth. No.

Beer w/Straw
2009-Dec-18, 05:00 AM
Thank you for the time in posting replies.

That is a lot of information to go over.

Again, thanks.

Beer w/Straw
2009-Dec-31, 04:26 PM
Is there info on the space craft and what it plans to do?

http://news.aol.ca/article/russia-may-send-spacecraft-to-knock-away-asteroid/762898/

01101001
2009-Dec-31, 06:22 PM
Is there info on the space craft and what it plans to do?

http://news.aol.ca/article/russia-may-send-spacecraft-to-knock-away-asteroid/762898/

Yesterday's news. It is being discussed in topic: Russia on Apophis (http://www.bautforum.com/space-exploration/98760-russia-apophis.html).