High speed objects in space

[enigmatic]

I'm not entirely sure how to phrase this question

I know it's possible for objects for objects in space to reach very high velocity relative to specific other objects. I'd always been left under the impression that most of the major objects (such as significant chunks of mass) were moving relatively (considering the magnitude of the numbers we are talking about here) slowly in respect to other major objects.
Are there any objects in space that are moving at VERY high velocity (say an appreciable fraction of C) with respect to others (say the solar system) and is there any way we could detect such objects.

I mean to say is there any reason the earth couldn't suddenly be beaned by a few grains of sand travelling at 1/3rd the speed of light that just happened to be passing through?

[Podkayne]

There are certainly subatomic particles traveling at relativistic speeds but they have an electric charge that is large compared to their mass, which allows them to be accelerated to high speeds by electromagnetic forces.

It's hard to imagine a physical mechanism that could accelerate grains of dust to relativistic velocities. Also, a dust grain has a much larger cross-sectional area than a subatomic particle, so it's much more likely to run into something as molecules or other pieces of dust as it whizzes though the Galaxy. Yeah, space is empty, but any object traveling many ightyears through the Galaxy has a nonzero chance of hitting something.

[Exapno Mapcase]

Ultra-high energy cosmic ray particles can travel at .9999999C or higher.

http://www.physics.adelaide.edu.au/astrophysics/cr.html
The origin of the highest energy cosmic rays is one of the outstanding puzzles in astrophysics. These particles (mostly protons, but including heavier atomic nuclei) have energies of up to around 1020eV (16 Joules), over fifty million times more energetic than the particles produced by the Fermilab Tevatron accelerator. We can only speculate about the conditions at the their cosmic source, because we know of no standard object (supernova, pulsar, or even a black hole) that could easily accelerate particles to such enormous energies.

Larger sized particles can be blown at high speeds as a result of supernovas. Whether they can get up to sand-grain size or such appreciable fractions of C is something I'll let the experts talk to.

I guess your question is something like whether they would vaporize the earth if one hit? Probably not. I think they would burn up in the atmosphere like any other meteor.

Can we detect grains of high-speed sand? Probably not, as well.

[enigmatic]

That's pretty much what I was thinking, that (absent the possibility of some intelligent race firing chunks of stuff around because they're bored) most of the stuff in space is travelling fairly slow compared to the speed limit.

The second question is, assuming for 1 minute that there was some totally unknown class of large stellar(?) objects that were, for whatever reason, flying around at such high speed, could we have any chance to actually detect them?

How do we know that all the dark matter isn't actually present and correct and zipping past our metaphorical ears apart from the lack of plausible ways to explain why it was moving so fast.

Again apologies if this doesn't make any sense (I'm a mere biologist)

[Podkayne]

The second question is, assuming for 1 minute that there was some totally unknown class of large stellar(?) objects that were, for whatever reason, flying around at such high speed, could we have any chance to actually detect them?

Sure. We can see on the order of 1000 ly even into the deepest, dustiest parts of the galactic disk, so it's not like something could zip past so fast that we couldn't see it. Even if it was going at nearly c, we'd have thousands of years to watch it.

A star moving at relativistic speeds relative to Earth would look really weird, and would attract a lot of attention. Even if the object itself was cool and dark, it would be plowing through the interstellar medium, and leave a bright tail of ionized gas (kind of like a meteor going though the Earth's atmosphere, now that I think about it.)

[Squink]

Are there any objects in space that are moving at VERY high velocity (say an appreciable fraction of C) with respect to others (say the solar system) and is there any way we could detect such objects.Several of the stars orbiting the black hole at the center of the Milky Way (http://antwrp.gsfc.nasa.gov/apod/ap051023.html) are moving at a pretty good clip.
S2 (http://arxiv.org/abs/astro-ph/0210426) hits 1.6% of lightspeed at its closest approach to the hole, and SO-16 (http://newsroom.ucla.edu/page.asp?id=3902) reaches 7.8% of lightspeed (52 million miles per hour).

[Whack-a-Mole]

Ultra-high energy cosmic ray particles can travel at .9999999C or higher.

http://www.physics.adelaide.edu.au/astrophysics/cr.html


Here's an even faster one:

On the night of October 15, 1991, the Fly's Eye detected a proton with an energy of 3.2±0.9×10^20 electron volts.[1,2] By comparison, the recently-canceled Superconducting Super Collider (SSC) would have accelerated protons to an energy of 20 TeV, or 2×10^13 electron volts--ten million times less. The energy of the Oh My God particle seen by the Fly's Eye is equivalent to 51 joules--enough to light a 40 watt light bulb for more than a second--equivalent, in the words of Utah physicist Pierre Sokolsky, to "a brick falling on your toe." The particle's energy is equivalent to an American baseball travelling fifty-five miles an hour.

<snip>

How fast was it going? Pretty fast.

v = 0.9999999999999999999999951 c

So taking 3×10^8 metres per second as the speed of light, we find that the particle was traveling 2.9999999999999999999999853×10^8 metres per second, thus 1.467×10^-15 metres per second slower than light--one and a half femtometres per second slower than light. If God's radar gun is slightly out of calibration, this puppy's gonna be doin' hard time for speeding. After traveling one light year, the particle would be only 0.15 femtoseconds--46 nanometres--behind a photon that left at the same time.

SOURCE: http://www.fourmilab.ch/documents/ohmygodpart.html

As for spotting much of anything out there realize that it is in fact a rather difficult task. Unless the object in question is radiating energy or having a noticeable effect on some nearby body that we can observe chances are pretty good whatever it is will be missed. As it is astronomers have a hard enough time trying to spot potential incoming earth killing asteroids and it was only last summer that astronomers discovered a possible tenth planet in our own solar system (ok....jury is still out on whether it is a "planet" but it is bigger than Pluto [which many say also should not be considered a planet]). None of these are moving especially fast but they are relatively close to us compared to some interstellar object.

[Yeticus Rex]

Gas jets accelerated from the poles of pulsars, neutron stars, and black holes. (http://www.google.com/search?hl=en&q=gas+jets+from+neutron+stars+speed+of+light)

[CalMeacham]

I'd always been left under the impression that most of the major objects (such as significant chunks of mass) were moving relatively (considering the magnitude of the numbers we are talking about here) slowly in respect to other major objects.


I think this is a misconception deriving from the way things in space are often depicted in movies -- tumbling slowly around, not "falling" because they're not close to another body. In addition, things in the same orbit near one another necessarily have to be moving at about the same velocity, or else they wouldn't be in the same orbit.

"Fast" itself is a relative term, but objects in space, while not necessarily moving at relativistic speeds, are often moving at pretty impressive velocities relative to other things. You can see what happens when things not in the same orbit collide. One good example was when comet Shoemaker-Levy collided with Jupiter back in 1994. Those devastating impacts were due to colossal velocity differences, not because of the comets falling in thwe gravitational pull of Jupiter. http://www2.jpl.nasa.gov/sl9/


Another example is the damage to space satelliters and spacecraft due to orbiting junk around the earth. There have been pretty interesting pictures of micro=damage caused by (it's believed) high velocity paint chips. At least one satellite loss is thought to be due to a collision.


Then there are all those craters on the moon, mercury, the satellites, and earth itself.


In all these case the items colliding were orbiting the same body, but not in similar orbits -- their orbits just happened to coincide in space at that one moment of time. In general, two items in space will not be moving with approximately the same velocity, and when they meet, sparks will fly.

[Nars Glinley]

Here's a recent thread (http://boards.straightdope.com/sdmb/showthread.php?t=344032) on fast moving objects.

[Exapno Mapcase]

Whack-a-Mole, that's exactly what I was thinking of, except that I forgot the "Oh My" part of it. So when I searched on the God Particle, I got info on the Higgs Boson, which is another thing entirely.

Thanks for finding that.