PeterDonis's latest activity
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).The path of Mars in the sky has nothing to do with how far Mars is from Earth. The loop in your image does not show that Mars is closer... -
PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).To be clear, this refers to the "loop" drawings at the top of your images, not to the circles representing the planetary orbits and the...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).There is no such thing in your animations. They don't even represent enough of what's going on in the "loops" for there to be any such...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).The loops in your animation are actually not even correctly representing loops. See below. Actually, even that's not true. Your...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).The loops are not representing the complete path of Mars in an Earth-centered frame. They are representing the apparent position of Mars...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).Of course--the first part of the loop is before opposition, when the Earth-Mars distance is decreasing, and the second part of the loop...
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PeterDonis replied to the thread High School Can gravitons be detected?.A single bar detector can only detect a fairly narrow range of frequencies of gravitational waves. Also it is not very sensitive as...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).Just to belabor this a little more: :wink: We expect that the three factors in the above formula are actually not independent. We know...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).Because, as my post #32 shows, it affects the distance that each planet travels perpendicular to the line of opposition (the major axis...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).No, it starts before opposition. That's obvious from the ephemeris data on JPL Horizons; the reversal of both right ascension and...
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PeterDonis replied to the thread High School Can gravitons be detected?.If by "stop the gravitational wave" you mean "absorb all its energy", no. A gravitational wave is not just one graviton. Indeed, we...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).I've tried constructing an approximate model by using small segments of circles to approximate the elliptical planetary orbits near...
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PeterDonis reacted to Sylvain9595's post in the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars) with
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I admit you are right, I get it now. I was too focused on the retrograde motion for some reason... -
PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).I don't think images are the best source to use. I'm going by the actual ephemeris data I pulled from JPL Horizons and gave in post #16...
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PeterDonis replied to the thread Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars).Actually, using motion along the ecliptic makes the difference almost a factor of three, so if anything it increases the "mystery".