6 ms·

210,000 kilometers per hour. Almost 60km/40mi per second. Amazing speed when you think about it. Wonder if there would be any time dilation noticable if the cra

210,000 kilometers per hour. Almost 60km/40mi per second. Amazing speed when you think about it. Wonder if there would be any time dilation noticable if the craft ever gets captured and brought back to earth.

ericbarrett 4y ago
Similarly I wonder if there was any detectable heating from kinetic interaction with dust and trace atmosphere. 60 km/sec is fast!
- orbital-decay 4y ago
  Not sure about the composition of atmosphere at those exact altitudes on Jupiter, but aerodynamic heating was a serious concern during Cassini's close Titan flybys, and that's "just" at ~6.3km/s max. IIRC the closest one was the T-70 at 880km; a lot of work has been done to make sure it won't tumble or overheat. (Titan's low gravity makes its dense atmosphere reach very far, so 880km is really low)
pvg 4y ago
Relativistic effects are measurable with accurate enough clocks in earth satellites (or even just taking a clock to a mountain) and correction is necessary in systems with finicky time requirements like GPS. Incidentally, the relative speed you can napkin math estimate - an object in orbit flying that close to the planet is going to have escape-velocity-ish speed. It's around 60km/sec for Jupiter.
- dmd 4y ago
  > taking a clock to a mountain http://www.leapsecond.com/great2005/tour/ http://www.leapsecond.com/great2005/tour/
  - belter 4y ago
    They also did the First Atomic Clock Wristwatch... http://leapsecond.com/pages/atomic-bill/ http://leapsecond.com/pages/atomic-bill/
  - cmroanirgo 4y ago
    Fantastic! Has this been shared on HN before? > We would come back about 20 ns older compared to her [the wife who stayed behind]. ≥ Or, the other way to look at it (since this is relativity after all), is that she would become 20 ns younger than us upon our return. Note to husbands: this could be a useful gift idea for your wife.
    - pvg 4y ago
      It has, in the HN equivalent of the Archean eon https://news.ycombinator.com/item?id=598090 https://news.ycombinator.com/item?id=598090
- atoav 4y ago
  By now I think they managed to measure relativistic effects of clocks that are a few milimeters apart in terms of distance from earths gravitational center.
  - pvg 4y ago
    Sufficiently clever experimentalists also pulled this off in about 20 meters in 1959, the clever bit being ditching the clocks entirely: https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment
rococode 4y ago
It's about 0.01% the speed of light, which is definitely fast enough to have a measurable impact. Even ISS astronauts experience a tiny amount of time dilation (on a millisecond level) and they move at much slower speeds.
arghwhat 4y ago
As a point of reference, our solar system orbits our galaxy at approximately 4 times that speed at 828 megameters per hour, so 210 megameters per second isn't that big a deal in the grand scheme of things...
- _Microft 4y ago
  Kilometer is the largest SI-prefixed variation of meter that is commonly used (among physicists that I know). I would rather suggest that you use scientific notation if you do not want to deal with large numbers of kilometers.
  - arghwhat 4y ago
    We don't stop at millimeters or kilowatt, so there is really no reason to stop at kilometer when megameter is more appropriate. Scientific notation is also fine, but "210 megameter" is in my opinion easier to read than "2.1 * 10^8 meters", especially for the casual reader. So while I respectfully make note of your feedback, I strongly disagree and stand by my choice of units. :)
    - ksaj 4y ago
      Given how hard it is to convince most Americans to use prefixed metre measurements instead of inches, feet, yards and miles, I think it would be even harder to convince the world that a megametre, picometre, etc is the way to go. Not that I don't agree (I fully do!), the ease of using multiples of 10 is way easier. But it is very difficult to introduce change to the masses, no matter how sensible it is. The US is one of the only countries on the planet that still fully stick to the old system. And they're also one of the only countries that spell 'meter' instead of 'metre.' For everyone else in the world, 'meter' is a measuring gauge or tool, and so is everything that rhymes with 'thermometer' except for the American pronunciation of 'kilometre' that too many have adopted up here. Likewise, adult Canadians still use pounds at the gym and their body weight, and feet/inches for their height. Young people are far more reasonable about measurements these days. Change is hard, and seems to get really messy when everyone goes in different directions from the start.
belter 4y ago
They are noticed in the Parker Solar Probe. At closest approach it get's to 590,000 kilometers per hour (aprox 360,000 mph) "Parker Solar Probe passing extremely close to the Sun; what relativistic effects will it experience and how large will they be?": https://physics.stackexchange.com/questions/348854/parker-solar-probe-passing-extremely-close-to-the-sun-what-relativistic-effects https://physics.stackexchange.com/questions/348854/parker-so...
Crontab 4y ago
I've read that time moves a tiny bit slower on Earth than it does in space and that it affects satellites. I wonder how much difference there is for something like the Voyagers, which has been in space since the 70's, and us on the ground.
- ncmncm 4y ago
  You could calculate it yourself. It would be a good exercise. Wolfram Alpha could be helpful.
andrekandre 4y ago
> 210,000 kilometers per hour. that would get you to the moon in about one and a half hours... crazy (cool)

ericbarrett 4y ago

Similarly I wonder if there was any detectable heating from kinetic interaction with dust and trace atmosphere. 60 km/sec is fast!

orbital-decay 4y ago
Not sure about the composition of atmosphere at those exact altitudes on Jupiter, but aerodynamic heating was a serious concern during Cassini's close Titan flybys, and that's "just" at ~6.3km/s max. IIRC the closest one was the T-70 at 880km; a lot of work has been done to make sure it won't tumble or overheat. (Titan's low gravity makes its dense atmosphere reach very far, so 880km is really low)

pvg 4y ago

Relativistic effects are measurable with accurate enough clocks in earth satellites (or even just taking a clock to a mountain) and correction is necessary in systems with finicky time requirements like GPS. Incidentally, the relative speed you can napkin math estimate - an object in orbit flying that close to the planet is going to have escape-velocity-ish speed. It's around 60km/sec for Jupiter.

dmd 4y ago
> taking a clock to a mountain http://www.leapsecond.com/great2005/tour/ http://www.leapsecond.com/great2005/tour/
- belter 4y ago
  They also did the First Atomic Clock Wristwatch... http://leapsecond.com/pages/atomic-bill/ http://leapsecond.com/pages/atomic-bill/
- cmroanirgo 4y ago
  Fantastic! Has this been shared on HN before? > We would come back about 20 ns older compared to her [the wife who stayed behind]. ≥ Or, the other way to look at it (since this is relativity after all), is that she would become 20 ns younger than us upon our return. Note to husbands: this could be a useful gift idea for your wife.
  - pvg 4y ago
    It has, in the HN equivalent of the Archean eon https://news.ycombinator.com/item?id=598090 https://news.ycombinator.com/item?id=598090
atoav 4y ago
By now I think they managed to measure relativistic effects of clocks that are a few milimeters apart in terms of distance from earths gravitational center.
- pvg 4y ago
  Sufficiently clever experimentalists also pulled this off in about 20 meters in 1959, the clever bit being ditching the clocks entirely: https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experiment

rococode 4y ago

It's about 0.01% the speed of light, which is definitely fast enough to have a measurable impact. Even ISS astronauts experience a tiny amount of time dilation (on a millisecond level) and they move at much slower speeds.

arghwhat 4y ago

As a point of reference, our solar system orbits our galaxy at approximately 4 times that speed at 828 megameters per hour, so 210 megameters per second isn't that big a deal in the grand scheme of things...

_Microft 4y ago
Kilometer is the largest SI-prefixed variation of meter that is commonly used (among physicists that I know). I would rather suggest that you use scientific notation if you do not want to deal with large numbers of kilometers.
- arghwhat 4y ago
  We don't stop at millimeters or kilowatt, so there is really no reason to stop at kilometer when megameter is more appropriate. Scientific notation is also fine, but "210 megameter" is in my opinion easier to read than "2.1 * 10^8 meters", especially for the casual reader. So while I respectfully make note of your feedback, I strongly disagree and stand by my choice of units. :)
  - ksaj 4y ago
    Given how hard it is to convince most Americans to use prefixed metre measurements instead of inches, feet, yards and miles, I think it would be even harder to convince the world that a megametre, picometre, etc is the way to go. Not that I don't agree (I fully do!), the ease of using multiples of 10 is way easier. But it is very difficult to introduce change to the masses, no matter how sensible it is. The US is one of the only countries on the planet that still fully stick to the old system. And they're also one of the only countries that spell 'meter' instead of 'metre.' For everyone else in the world, 'meter' is a measuring gauge or tool, and so is everything that rhymes with 'thermometer' except for the American pronunciation of 'kilometre' that too many have adopted up here. Likewise, adult Canadians still use pounds at the gym and their body weight, and feet/inches for their height. Young people are far more reasonable about measurements these days. Change is hard, and seems to get really messy when everyone goes in different directions from the start.

belter 4y ago

They are noticed in the Parker Solar Probe. At closest approach it get's to 590,000 kilometers per hour (aprox 360,000 mph) "Parker Solar Probe passing extremely close to the Sun; what relativistic effects will it experience and how large will they be?": https://physics.stackexchange.com/questions/348854/parker-solar-probe-passing-extremely-close-to-the-sun-what-relativistic-effects https://physics.stackexchange.com/questions/348854/parker-so...

Crontab 4y ago

I've read that time moves a tiny bit slower on Earth than it does in space and that it affects satellites. I wonder how much difference there is for something like the Voyagers, which has been in space since the 70's, and us on the ground.

ncmncm 4y ago
You could calculate it yourself. It would be a good exercise. Wolfram Alpha could be helpful.

andrekandre 4y ago

> 210,000 kilometers per hour. that would get you to the moon in about one and a half hours... crazy (cool)