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posted by martyb on Saturday November 04 2017, @09:40PM   Printer-friendly
from the it-doesn't-matter dept.

A pair of researchers from the University of Nevada, Reno, in an attempt to detect and better define dark matter, have pulled off a pretty amazing science experiment. The team used 16 years worth of GPS data to turn the whole planet into a massive detector that might detect clumps of dark matter that could extend beyond the solar system.

Dark matter makes up roughly 85% of all matter in the universe, which is a real bummer for us humans — as we simply have no idea what it is, what it looks like, nothing. Astrophysics has provided multiple evidence that it actually exists, but so far, it’s always been beyond our grasp. As generally tends to happen when faced with great unknowns, we do however have quite a lot of hypotheses pertaining to its nature.

"So, the two gathered data from the 32 satellites that make up the 31,000-mile-wide GPS constellation and ground-based GPS stations, retrieving figures recorded every 30 seconds for the last 16 years. Data was retrieved from sources around the world, and in particular from NASA’s Jet Propulsion Laboratory. They then used a model to sift through this data, looking for irregularities in atomic clock signals.

[...] Aaaaaaand they didn’t find anything. It’s a bit disappointing, sure, but it’s not really surprising given how elusive dark matter has proven itself to be up to now. It has to be said, however, that while the team didn’t find any definitive proof to support their theory, it could be that the effect is simply more subtle than anything we can pick up, or that the Earth crosses lumps of dark matter very rarely."

https://www.zmescience.com/science/earth-dark-matter-sensor-gps/


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  • (Score: 2) by Immerman on Sunday November 05 2017, @03:45PM (3 children)

    by Immerman (3985) on Sunday November 05 2017, @03:45PM (#592541)

    Not a very good one - a proper spiral would require the planetary orbital plane to be perpendicular to the direction of the sun's motion. Since the orbital plane is inclined about 63 degrees from the galactic plane, that never happens.

    Even if it did happen it wouldn't last long as angular momentum means the solar system's plane remains roughly constant while the sun's direction constantly changes as it circles through the galaxy, meaning that if at galactic "equinox" we were tracing a perfect spiral, then a quarter rotation away at galactic "solstice" the solar system would be traveling edge-on. In reality though we just kind of wobble along, occasionally traveling edge-on, but never perpendicular. Probably for the best, as traveling pole-first through the galaxy would likely let a lot more interstellar material in through the sun's magnetosphere.

    From a visualization perspective though the relative speeds involved are close enough that you could at least see the wobbly spiral in a simulation - in the 88 days it takes the fastest-orbiting/tightest spiraling planet Mercury to travel it's 364 million km orbit around the sun, the solar system has traveled 1,749 million km - if it were perpendicular, that would be a spiral circling a standard pencil once every 89mm (3.5 in). Though in reality it would be more of an elliptic spiral whose coils are a little bit "pinched tight" on one side where some of the planet's motion is opposing that of the sun and "stretched out" of the other where their direction partially aligns. Except as we approach "solstice" and travel edge-on, when planet paths degenerate into to a 2-dimesional pseudo-sine wave.

    Sorry if that was too much information - I may have been a little triggered. I've seen that %$#@!ing "vortex" animation of the sun towing the spiraling planets behind it recirculate far too many times - the reality is that all the planets spend half their orbit traveling in front of the sun through the galaxy.

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  • (Score: 0) by Anonymous Coward on Sunday November 05 2017, @08:35PM (2 children)

    by Anonymous Coward on Sunday November 05 2017, @08:35PM (#592646)

    Well I didn't mean to claim anything about a "proper" spiral, eg where the sun is supposed to be in front of the planets for some reason (why?).

    I meant spiral in a generic sense. I assure you, the orbits are spirals when you don't center on the sun or SSB and give the sun a velocity.

    From a visualization perspective though the relative speeds involved are close enough that you could at least see the wobbly spiral in a simulation - in the 88 days it takes the fastest-orbiting/tightest spiraling planet Mercury to travel it's 364 million km orbit around the sun, the solar system has traveled 1,749 million km - if it were perpendicular, that would be a spiral circling a standard pencil once every 89mm (3.5 in).

    It isn't something you can barely notice. It is very obvious. At least if you put "tails" to represent the past locations of each object.

    the reality is that all the planets spend half their orbit traveling in front of the sun through the galaxy.

    Why is this aspect important to you?

    • (Score: 2) by Immerman on Sunday November 05 2017, @10:52PM (1 child)

      by Immerman (3985) on Sunday November 05 2017, @10:52PM (#592697)

      The sun will never stay in front of the planets no matter what - at most they'll all be (approximately) equally "front", at least in terms of center of mass. The vortex B.S. always shows the sun leading though, dragging the planets in its wake. Like I said, think I got a bit triggered.

      I did not mean to suggest that it was something you would barely notice - just wanted to put it in easily visualized perspective (incidentally, what do you use that lets you trace the planets path through the galaxy?)

      • (Score: 0) by Anonymous Coward on Monday November 06 2017, @03:40AM

        by Anonymous Coward on Monday November 06 2017, @03:40AM (#592804)

        I just coded up a newtonian mechanics model one time in c++/R (rgl package for 3d visualizations), getting the starting points for everything from jpl horizons. I store the history and display the last n values trailing behind a sphere. The "galaxy" is just a bunch of random points, so its nothing crazy but I was impressed by the spirals.