[HN Gopher] Asteroid that broke up over Berlin was fastest-spinn...
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Asteroid that broke up over Berlin was fastest-spinning one ever
seen
Author : gnabgib
Score : 36 points
Date : 2024-05-02 18:44 UTC (4 hours ago)
(HTM) web link (www.newscientist.com)
(TXT) w3m dump (www.newscientist.com)
| tosser0001 wrote:
| That doesn't seem particularly fast of a spin and I'm surprised
| it's the fastest one observed.
|
| There is a moment in 2001: A Space Odyssey that I've always
| liked. It's at about 1:13:15 or so, and is just a distant shot of
| the Discovery One. Suddenly two space rocks silently tumble past.
| I like the scene because it gives a sense of the scope and
| silence of outer space, but I suppose it would be incredibly rare
| to be so close to even one rock, let alone a pair. And they are
| tumbling at about the pace measured by the one in that article,
| so perhaps even rarer still.
| WJW wrote:
| Well as the article states the bigger ones would tear
| themselves apart if they spun too fast so that is one reason.
| In the end they are just big rocks and thus not very good at
| tensile loads...
| sholladay wrote:
| I'm surprised to learn that one rotation every 2.6 seconds is the
| fastest we've ever seen. That actually seems kind of slow. I can
| think of lots of things that rotate faster than that, including
| me if I want to. Is this mainly because the solar system is old
| and energy has dissipated over time?
| rqtwteye wrote:
| I am not sure about the exact numbers but I would think objects
| of a certain size would fall apart if they spin too fast. I
| think I read that this is 1m. Spinning that fast creates some
| significant centrifugal force.
| antognini wrote:
| There are two main mechanisms that cause asteroids to spin. The
| first is as a result of collisions, which is fairly intuitive.
| But even in the absence of any collisions asteroids can acquire
| spin due to the YORP Effect (named after Yarkovsky, O'Keefe,
| Radzievskii, and Paddock). The idea is that if the surface is
| anisotropic (which is true of asteroids), then as the asteroid
| radiates heat, the photon pressure will be anisotropic and will
| start to impart a torque onto the body.
| jjtheblunt wrote:
| https://en.wikipedia.org/wiki/Radiometer
|
| That's a toy i had as a kid, essentially!
| hoerensagen wrote:
| Thase are great. here is a brilliant technology connections
| video about it.
|
| https://youtu.be/t-JN2U4jHgk?feature=shared
| z2h-a6n wrote:
| Not to nitpick (I only stumbled upon this recently myself),
| but the mechanism driving a Crookes radiometer (which I
| presume is the type you're talking about) is not photon
| pressure, but interactions with the low pressure gas in the
| bulb [1].
|
| [1]: https://en.wikipedia.org/wiki/Crookes_radiometer#Explana
| tion...
| amelius wrote:
| > space rocks larger than a kilometre can't rotate more than once
| every 2.2 hours because they would break apart.
|
| Curious, what is that number for a space rock the size of Earth?
| WJW wrote:
| At some point gravitational forces start counteracting
| centrifugal forces again, so density means a lot. Apparently
| the fastest-spinning neutron star known so far spins at about
| 716 rotations per second. (see
| https://en.wikipedia.org/wiki/Neutron_star)
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