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Minute Physics 3 Dec 2025 35 here now

The TROJAN Test

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How do we truly know if something is orbiting something else? You may be familiar with the b

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Comments (20)

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The JWST is actually at one of our planet’s LaGrange points!
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NOW THIS is perfect (several) minute physics content :)
Lovely topic, great explanation, entirely logical suggestion as well. Thanks for sharing, thanks for teaching!!
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i was expecting this to be about how we know that the moon is a rock that orbits the earth and not something else but this is fine too
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I love this. A simple solution that upon closer inspection turns out to be problematic, leading to a much better solution.
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@JH-tc3yu From YouTube ↗ 21 Dec 2025 4
Classic minutephysics video, I love the return to form. Feels very comforting
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@Exkhaniber From YouTube ↗ 21 Dec 2025 41
Fascinating video. Also it kinda feels like a response video directed to the comments on the prior video about orbits where people talking about using that barycenter as their defining point.
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@Doktor_Vem From YouTube ↗ 21 Dec 2025 38
Happy to see that you're still making videos, mate ^^
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@Stratelier From YouTube ↗ 21 Dec 2025 32
0:48 - "Planet" confirmed, it "cleared the neighborhood" from all that dry-erase marker debris!
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1:56 The caption implies you don't consider brown dwarfs to be stars, but the drawing gives 13 Jupiter masses as the cut-off, which is lower limit for brown dwarfs. If you don't consider brown dwarfs to be stars, then the cut-off is 70 Jupiter masses.
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The animation at 1:28 is downright beautiful. My brain loves it.
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Right in that narrow window where it's something I haven't heard about but simple enough for me to understand. I like it.
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@jvdos From YouTube ↗ 21 Dec 2025 521
for a second I thought this was gonna be a video about how we figured out that the moon generally goes around the earth, considering its the only thing that actually does orbit the earth, which slightly complicated the conversation around heliocentrism. Once galileo showed Jupiter had moons though, it became obvious both the planets and the sun could have (what would come to be called) satellites.
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@FoxDog1080 From YouTube ↗ 21 Dec 2025 35
I love how slowly the rocket at L3 drifts at 2:54
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Pluto: "Dude called us a binary *PLANET*!!!"
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@Yonkage-ik5qb From YouTube ↗ 21 Dec 2025 1000
"The physical definition of a star, where below a certain mass you can't do fusion."

Hydrogen bomb: I'm something of a star, myself.
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That's no moon...wait, no, that's definitely a moon
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@bipo1040 From YouTube ↗ 21 Dec 2025 254
I never thought about the problems with the barycenter definition. And never imagined that the L4/L5 points could be useful to determine if a system is a "binary" or not. Great video!
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Fun fact: The cutoff for the mass ratio is not actually 25, but (25 + 3*sqrt(69))/2 ≈ 24.96. Lots of complicated math to derive it!
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1:54 I'm envious of how simple that drawing of Jupiter is while still being so clearly a drawing of Jupiter
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I once learned that the L4/L5 bodies are called "Trojans", because they are chasing each other like Achilles chased Hector around Troy to avenge the death of Patroclos. Hence, the L4 bodies are called the "Hector group" and the L5 bodies are called the "Achilles group". And that's why the bodies in the L4 and L5 points of Jupiter were named after characters in the Trojan War, because Jupiter was the first planet where those bodies were found.