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NASA reports that the Parker Solar Probe[*] Completes Fourth Closest Approach, Breaks New Speed and Distance Records:
At 4:37 a.m. EST on Jan. 29, 2020, NASA's Parker Solar Probe broke speed and distance records as it completed its fourth close approach of the Sun. The spacecraft traveled 11.6 million miles from the Sun's surface at perihelion, reaching a speed of 244,225 miles per hour. These achievements topple Parker Solar Probe's own previous records for closest spacecraft to the Sun — previously about 15 million miles from the Sun's surface — and fastest human-made object, before roughly 213,200 miles per hour.
[*] Wikipedia's entry for the Parker Solar Probe:
The Parker Solar Probe (previously Solar Probe; Solar Probe Plus or Solar Probe+, abbreviated PSP) is a NASA robotic spacecraft launched in 2018, with the mission of repeatedly probing and making observations of the outer corona of the Sun. It will approach to within 9.86 solar radii (6.9 million kilometers or 4.3 million miles) from the center of the Sun and by 2025 will travel, at closest approach, as fast as 690,000 km/h (430,000 mph), or 0.064% the speed of light.
In other words, at the so-far-fastest speed, one could travel from the Earth to the Moon in as little as 55 minutes when the Moon is at perigee. At its maximum expected speed, it could travel that distance in as little as 30 minutes!
(Score: 2) by PiMuNu on Tuesday February 04 2020, @09:51AM (14 children)
in what frame of reference?
(Score: 0) by Anonymous Coward on Tuesday February 04 2020, @11:59AM (12 children)
(Score: 2) by PiMuNu on Tuesday February 04 2020, @12:34PM (11 children)
> Relative to the sun.
In which case the earth is travelling faster?
(Score: 2) by martyb on Tuesday February 04 2020, @01:30PM (7 children)
Last I knew, the Earth was not.... human-made.
=)
Wit is intellect, dancing.
(Score: 3, Insightful) by PiMuNu on Tuesday February 04 2020, @02:43PM (6 children)
> Last I knew, the Earth was not.... human-made.
But cars, and cheese, and keyboards are, and they are all travelling faster than the Parker Solar Probe, relative to the sun. Just sayin'.
(Score: 4, Informative) by martyb on Tuesday February 04 2020, @03:27PM (4 children)
Good point, I had not thought of human-made objects on Earth! Unfortunately, even then, it looks like the Parker Solar Probe is even faster.
See: this article [space.com], specifically the section copied below:
The fine summary (which started this whole discussion) stated the Parker Solar Probe most-recently attained "244,225 miles per hour." I would hazard a guess that is somewhat more than Earth's "66,627 mph".
Besides, it was intended only as a joke... there was a "=)" to make try to make my intention apparent.
Wit is intellect, dancing.
(Score: 2) by PiMuNu on Tuesday February 04 2020, @04:40PM (3 children)
Yeah, I was being super-pedantic and also wrong! Because the Parker Probe is probably on an elliptic orbit so it goes faster than the earth even though it is closer. Circular orbits have higher speed as they go further out from the sun.
(Score: 0) by Anonymous Coward on Tuesday February 04 2020, @04:56PM
And so do elliptical orbits. What makes circular orbits unique is that they have constant speed.
(Score: 1, Informative) by Anonymous Coward on Tuesday February 04 2020, @04:59PM
Whoops, read yours backwards in my reply above. The further away from the body you are, the slower your speed. Your statement would be true only if every body went around in their orbit in the same amount of time, but as you know, it takes the outer planets much longer to go around the Sun once than it does the Earth.
(Score: 3, Informative) by Immerman on Tuesday February 04 2020, @05:31PM
>Circular orbits have higher speed as they go further out from the sun.
Nope.
Kepler's Law states: The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.
So the orbital period is proportional to R^(3/2), and increases super-linearly with R
Meanwhile the distance the planet travels per orbit increases linearly with R (circumference = 2*pi*R), and so the linear speed v = distance/time, so
v proportional to R / R^(3/2) = 1/sqrt(R)
So speed decreases gradually with distance: 4x as far out = 1/2 the speed.
(Score: 2) by corey on Wednesday February 05 2020, @09:02AM
Ahh take your relativity "fact talk" somewhere else, it's ruining the story!
(Score: 1, Informative) by Anonymous Coward on Tuesday February 04 2020, @01:36PM (1 child)
(Score: 2) by PiMuNu on Tuesday February 04 2020, @02:59PM
I realise I was assuming circular orbit. Probably it is on elliptical orbit which can be much faster.
(Score: 1) by khallow on Tuesday February 04 2020, @04:04PM
Nope. Earth travels roughly 30 km/s relative to the Sun, at closest approach the spacecraft was going 100 km/s.
(Score: 0) by Anonymous Coward on Tuesday February 04 2020, @01:32PM
In reference to the space/time point that the alien clicked its Space Olympics Time Device.
(Score: 3, Interesting) by MostCynical on Tuesday February 04 2020, @12:02PM (1 child)
xkcd [xkcd.com]
if the sun were 1.1 metres in diameter, the earth would be 115m away, and 1cm in diameter,
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 0) by Anonymous Coward on Tuesday February 04 2020, @03:32PM
Why look at a cartoon when you can walk the model [jeffreybennett.com]?
This is a typical intro-astronomy class thing to do, which is take a basketball for the Sun and have the class do the planets out to Jupiter. I did it as a TA. I think it works out pretty nice for a softball for Jupiter, but I'd have to run the numbers again (it was 25 year ago after all).