# Fastest moving space mass **URL:** \ **Category:** Factual Questions\ **Created:** [November 8, 2018, 7:18pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208 "2018-11-08T19:18:48Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![HoneyBadgerDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/honeybadgerdc/32/1033_2.png) [@HoneyBadgerDC](https://boards.straightdope.com/u/HoneyBadgerDC)\ **Post date:** [November 8, 2018, 7:18pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/1 "2018-11-08T19:18:48Z")
How fast is the fastest known mass moving through space? Could Propelled spacecrafts exceed this speed? ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [November 8, 2018, 7:50pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/2 "2018-11-08T19:50:44Z")
It will depend on what reference point you mean. The Sun is moving around the galactic centre at ~200 km/s. [HE 0437-5439](https://en.wikipedia.org/wiki/HE_0437-5439) is an inter-galactic B class star moving at 723 km/s, which is impressive as hell. However that’s only about .002c, and we do/plan for probes like [Starwisp](https://en.wikipedia.org/wiki/Starwisp) to reach some fraction (~20%) of c. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [November 8, 2018, 7:53pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/3 "2018-11-08T19:53:59Z")
[Here](https://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray) is an article describing cosmic particles with energies over 10[sup]20[/sup] eV. Hard to beat that. Considering stuff squirted away from a black hole at a more prosaic speed like 25% or 30% of the speed of light, even theoretically proposed spacecraft employing technologies such as [nuclear propulsion](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) were not able to achieve such speeds. ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [November 8, 2018, 7:58pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/4 "2018-11-08T19:58:32Z")
Not sure what qualifies as a “mass”, but neutrinos are thought to have mass and travel negligibly (for a given value of ‘negligibly’) slower than c. ---
**Author:** ![Grey](https://avatars.discourse-cdn.com/v4/letter/g/b782af/32.png) [@Grey](https://boards.straightdope.com/u/Grey)\ **Post date:** [November 8, 2018, 8:10pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/5 "2018-11-08T20:10:31Z")
Good point. Like **DPRK** says cosmic rays can reach ludicrous speeds. The [Oh My God](https://en.wikipedia.org/wiki/Oh-My-God_particle) particle is listed as moving at 99.99999999999999999999951% of the speed of light. ---
**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\ **Post date:** [November 8, 2018, 8:47pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/6 "2018-11-08T20:47:39Z")
Galaxies with a redshift higher than 1.4 are (apparently) moving away from us with a velocity faster than light speed. When talking about cosmological distances, one needs to be very precise about what one means by “speed” and how it should be calculated. ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [November 8, 2018, 8:55pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/7 "2018-11-08T20:55:25Z")
Tachyons are particles, so they have mass. They move FASTER than the speed of light. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 8, 2018, 9:01pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/8 "2018-11-08T21:01:29Z")
The only trouble for tachyons is that we don’t know if they actually exist, and there’s no good reason to believe they do exist. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [November 8, 2018, 9:20pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/9 "2018-11-08T21:20:33Z")
> [@Lemur866](#): > > The only trouble for tachyons is that we don’t know if they actually exist, and there’s no good reason to believe they do exist. Also if they do exist, they have imaginary mass. Nor is it true that particle implies mass. Photons are particles without mass. ---
**Author:** ![Buck\_Godot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/buck_godot/32/6573_2.png) [@Buck\_Godot](https://boards.straightdope.com/u/Buck_Godot)\ **Post date:** [November 8, 2018, 9:51pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/10 "2018-11-08T21:51:49Z")
> [@Grey](#): > > Good point. Like **DPRK** says cosmic rays can reach ludicrous speeds. The [Oh My God](https://en.wikipedia.org/wiki/Oh-My-God_particle) particle is listed as moving at 99.99999999999999999999951% of the speed of light. To put this in perspective it is a proton or possibly an iron nucleus that has as much energy as dropping a 3.5 pound weight from 10 feet. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [November 8, 2018, 10:48pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/11 "2018-11-08T22:48:41Z")
To consider macroscopic objects, there are stars that are on galactic escape trajectories. That is, they have enough velocity in the right direction to escape the galaxy. At our distance from the galactic center, that’s about 540 km/sec. Some of these stars are well above that, 1000 to 2000 km/sec. There’s more than one mechanism that could give them that velocity, including a close passage to the black hole in the galactic center. Another one is to be one of a close binary star system where one star does a type Ia supernova. In this case, the two stars are both white dwarves and one grabs enough mass off the other one to supernova. In type Ia, the star is completely destroyed, so its partner no longer has anything to orbit. So the partner goes shooting off at its previous orbital speed. However, if you count orbital speed, there’s are faster things. We’ve detected several black hole mergers via LIGO. Those black holes were in orbit before merger. Their speeds just before their merger should be way faster than just about any other macroscopic object. I’m not sure anyone has calculated what velocity they had, though. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 9, 2018, 2:20am UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/12 "2018-11-09T02:20:26Z")
> [@](#): > > I’m not sure anyone has calculated what velocity they had, though. Of course folks have calculated it-- They’ve done full calculations for the exact motion throughout the merger. Without those calculations, we wouldn’t have been able to detect the mergers in the firs place. Suffice to say that it’s going to be a sizable fraction of c. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [November 9, 2018, 12:51pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/13 "2018-11-09T12:51:00Z")
> [@dtilque](#): > > To consider macroscopic objects, there are stars that are on galactic escape trajectories. That is, they have enough velocity in the right direction to escape the galaxy. At our distance from the galactic center, that’s about 540 km/sec. Some of these stars are well above that, 1000 to 2000 km/sec. Pfft, amateurs. [These folk](http://time.com/3602047/hypervelocity-stars/) think there’s trillions of stars moving at least a 10th of the speed of light and a few even faster. (None apparently observed yet. All based on extrapolating from the known range of speeds.) Note that if one of these blazed somewhat near a star system with a space tech civilization, they could send out probes that’d get a helluva gravitational boost. Assuming they could survive the blue shifted radiation and all. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 9, 2018, 6:43pm UTC](https://boards.straightdope.com/t/fastest-moving-space-mass/824208/14 "2018-11-09T18:43:20Z")
0.1c wouldn’t be all that much of a blueshift. I mean, it’d be a lot more than we’re used to observing, but it’s not like it’d turn visible light into gamma rays, or anything.