Comments on: What is the Fastest Spinning Object in the Solar System? Near-Earth Asteroid 2008 HJ http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/ Space and astronomy news Sun, 22 Nov 2009 03:07:54 -0600 http://wordpress.org/?v=2.8.6 hourly 1 By: Timothy Cookson http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-47186 Timothy Cookson Mon, 22 Dec 2008 05:01:20 +0000 http://www.universetoday.com/?p=14593#comment-47186 I would just like to say that this rotational speed is nothing compared to the fastest spinning pulsar. Recently discovered 1,122 rotations per second and no more than 20km in diameter. How about that centrifugal force? I would just like to say that this rotational speed is nothing compared to the fastest spinning pulsar. Recently discovered 1,122 rotations per second and no more than 20km in diameter. How about that centrifugal force?

]]> By: Quantum_Flux http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22261 Quantum_Flux Fri, 30 May 2008 02:44:39 +0000 http://www.universetoday.com/?p=14593#comment-22261 Wherever there's superfast spinning asteroid one you do see, there's about 1000 you don't see. Wherever there's superfast spinning asteroid one you do see, there's about 1000 you don't see.

]]> By: John Mendenhall http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22205 John Mendenhall Thu, 29 May 2008 16:46:09 +0000 http://www.universetoday.com/?p=14593#comment-22205 Ian "Hi Ron, we add a small description to each image in the "alt" tab of the images. The pic of Eros was used as an example of a near-Earth asteroid. The image was taken by the NEAR spacecraft when it orbited the body in 2001. Hope that helps " If I hover the pointer over the picture, the caption comes up. I'd like it better if the caption was there all the time. Ian "Hi Ron, we add a small description to each image in the "alt" tab of the images. The pic of Eros was used as an example of a near-Earth asteroid. The image was taken by the NEAR spacecraft when it orbited the body in 2001. Hope that helps "

If I hover the pointer over the picture, the caption comes up.

I'd like it better if the caption was there all the time.

]]> By: Ian O'Neill http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22180 Ian O'Neill Thu, 29 May 2008 12:39:59 +0000 http://www.universetoday.com/?p=14593#comment-22180 Hi Ron, we add a small description to each image in the "alt" tab of the images. The pic of Eros was used as an example of a near-Earth asteroid. The image was taken by the NEAR spacecraft when it orbited the body in 2001. Hope that helps :-) To Dutch Delight: The asteroid will have a small gravitational pull, so that will allow something like a basketball to stick to it, but it would take very little effort to acheive "escape velocity", so it would be a very unstable situation. However, if you factor in the spin of the rock, the centrepatal force will overwhelm the effect of gravity. It would be possible to maintain an orbit around the asteroid. So the basketball is most likely to be in orbit or flung into space by its spinning, it wont stick to the surface for long... Good stuff :) Ian Hi Ron, we add a small description to each image in the "alt" tab of the images. The pic of Eros was used as an example of a near-Earth asteroid. The image was taken by the NEAR spacecraft when it orbited the body in 2001. Hope that helps :-)

To Dutch Delight: The asteroid will have a small gravitational pull, so that will allow something like a basketball to stick to it, but it would take very little effort to acheive "escape velocity", so it would be a very unstable situation. However, if you factor in the spin of the rock, the centrepatal force will overwhelm the effect of gravity. It would be possible to maintain an orbit around the asteroid. So the basketball is most likely to be in orbit or flung into space by its spinning, it wont stick to the surface for long…

Good stuff :)

Ian

]]> By: john http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22178 john Thu, 29 May 2008 12:32:42 +0000 http://www.universetoday.com/?p=14593#comment-22178 Come in spinner. If you don't understand cricket, think lure fishing. I think this record will be broken. Come in spinner. If you don't understand cricket, think lure fishing. I think this record will be broken.

]]> By: Dutch Delight http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22159 Dutch Delight Thu, 29 May 2008 05:55:56 +0000 http://www.universetoday.com/?p=14593#comment-22159 So what happens if you put a basketball on the surface of this asteroid? Will it just sit there or start rolling around and possibly end up in orbit? So what happens if you put a basketball on the surface of this asteroid? Will it just sit there or start rolling around and possibly end up in orbit?

]]> By: Ron Jackson http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22152 Ron Jackson Thu, 29 May 2008 04:17:12 +0000 http://www.universetoday.com/?p=14593#comment-22152 Is the photo of 2008 HJ, taken with a 2 meter telescope? That is a small asteroid at 12x24 meters, so even though it is close I don't see how they got such high resolution. Wait a minute, perhaps I see the answer to my own question. That photo is eros.jpg. Maybe a Hubble image? Would be good to label things like that, so as to not be misleading. Is the photo of 2008 HJ, taken with a 2 meter telescope? That is a small asteroid at 12×24 meters, so even though it is close I don't see how they got such high resolution. Wait a minute, perhaps I see the answer to my own question. That photo is eros.jpg. Maybe a Hubble image?

Would be good to label things like that, so as to not be misleading.

]]> By: Astrofiend http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22139 Astrofiend Thu, 29 May 2008 01:28:30 +0000 http://www.universetoday.com/?p=14593#comment-22139 Ethan Siegel Says: May 28th, 2008 at 3:55 pm "Maybe someday we'll be finding ones that are *really* fast, where velocities will be measured in fractions of the speed-of-light, rather than paltry units like "meters per second". Not for asteroids... The centripetal force of self-gravity would not be nearly enough to stop them from flinging themselves apart long before such rotation speeds were reached... Although 2 m/s sounds slow, it is probably an appreciable fraction of the break-up rotation velocity for such a small object! Ethan Siegel Says:
May 28th, 2008 at 3:55 pm

"Maybe someday we'll be finding ones that are *really* fast, where velocities will be measured in fractions of the speed-of-light, rather than paltry units like "meters per second".

Not for asteroids… The centripetal force of self-gravity would not be nearly enough to stop them from flinging themselves apart long before such rotation speeds were reached…

Although 2 m/s sounds slow, it is probably an appreciable fraction of the break-up rotation velocity for such a small object!

]]> By: Ian O'Neill http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22133 Ian O'Neill Thu, 29 May 2008 00:16:21 +0000 http://www.universetoday.com/?p=14593#comment-22133 Hi Ethan: They say "great minds think alike" ;) To Jorge: You are right - this is supposed to read "fastest spinning natural object". Spin corrected satellites spin much faster - I think their spin could be measured in Hz, not rotations per minute :) Will add a note, thanks for highlighting that! Cheers all! Ian :) Hi Ethan: They say "great minds think alike" ;)

To Jorge: You are right – this is supposed to read "fastest spinning natural object". Spin corrected satellites spin much faster – I think their spin could be measured in Hz, not rotations per minute :) Will add a note, thanks for highlighting that!

Cheers all! Ian :)

]]> By: Jorge http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22130 Jorge Wed, 28 May 2008 23:50:35 +0000 http://www.universetoday.com/?p=14593#comment-22130 Er... spin doesn't have anything to do with gravity. Gravity derives from mass, and is totally independent from spin. Spin generates another type of force: centrifugal force, which depends on the angular velocity of the rotating body and the distance to the rotation axis. When you subtract the centrifugal force from gravity, you get weight. Not to be confused with mass. ;) And now regarding the article, I'm pretty sure that some man-made objects in orbit around the Earth or the Sun rotate much faster than this. Er… spin doesn't have anything to do with gravity. Gravity derives from mass, and is totally independent from spin.

Spin generates another type of force: centrifugal force, which depends on the angular velocity of the rotating body and the distance to the rotation axis.

When you subtract the centrifugal force from gravity, you get weight. Not to be confused with mass. ;)

And now regarding the article, I'm pretty sure that some man-made objects in orbit around the Earth or the Sun rotate much faster than this.

]]> By: Daniel Fischer http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22123 Daniel Fischer Wed, 28 May 2008 23:32:19 +0000 http://www.universetoday.com/?p=14593#comment-22123 > you are always beating me to the punch! How about a <a href="http://cosmos4u.blogspot.com/2008/05/one-rotation-every-43-seconds-fastest.html" rel="nofollow">report from May 22nd</a> then? > you are always beating me to the punch!

How about a report from May 22nd then?

]]> By: zeb http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22120 zeb Wed, 28 May 2008 23:19:28 +0000 http://www.universetoday.com/?p=14593#comment-22120 "Wonder how much gravity spinning like this would create" Assuming that its rotating on its short axis, 0.26 m/s^2, or about 0.027 g. Not much, but it obviously has to be a single solid body. "Wonder how much gravity spinning like this would create"

Assuming that its rotating on its short axis, 0.26 m/s^2, or about 0.027 g. Not much, but it obviously has to be a single solid body.

]]> By: Ethan Siegel http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22118 Ethan Siegel Wed, 28 May 2008 22:55:33 +0000 http://www.universetoday.com/?p=14593#comment-22118 Ian, you are always <a href="http://startswithabang.com/?p=533" rel="nofollow">beating me to the punch</a>! Maybe someday we'll be finding ones that are *really* fast, where velocities will be measured in fractions of the speed-of-light, rather than paltry units like "meters per second". This is actually pretty slow, clocking in at under 2 meters per second, slower than even I can run! Ian, you are always beating me to the punch! Maybe someday we'll be finding ones that are *really* fast, where velocities will be measured in fractions of the speed-of-light, rather than paltry units like "meters per second". This is actually pretty slow, clocking in at under 2 meters per second, slower than even I can run!

]]> By: Steve http://www.universetoday.com/2008/05/28/what-is-the-fastest-spinning-object-in-the-solar-system-near-earth-asteroid-2008-hj/comment-page-1/#comment-22112 Steve Wed, 28 May 2008 22:20:57 +0000 http://www.universetoday.com/?p=14593#comment-22112 Wonder how much gravity spinning like this would create Wonder how much gravity spinning like this would create

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