this post was submitted on 24 Mar 2024
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[–] victorz 23 points 7 months ago (3 children)

A rotating spheroid will oblate when its centrifugal force generates enough inertia to slightly flatten it out into a more irregular, elliptical shape.

I didn't know inertia could be generated. I thought mass just had inertia. Could someone explain? Are they talking out of their ass or is that statement actually accurate?

[–] mlg 12 points 7 months ago* (last edited 7 months ago) (1 children)

~~I think whoever wrote it just used the wrong word because yes inertia is dependent on mass, not momentum~~

Okay I actually decided to check and I think it just a poorly written explanation of rotational inertia

A rotating spheroid will oblate when its centrifugal force generates enough ~~inertia~~ angular momentum to slightly flatten it out into a more irregular, elliptical shape.

If the shape also changes, this would mean distribution of that mass relative to the axis of rotation would also have changed, which if I'm reading this right, affects rotational inertia.

[–] victorz 2 points 7 months ago

Thank you! I knew I wasn't crazy... 😬

[–] [email protected] 6 points 7 months ago (1 children)

Inertia is the tendency of objects in motion to stay in motion, and objects at rest to stay at rest, unless a force causes its speed or direction to change. from Wikipedia

So they're kind of just saying that once it picks up enough rotational speed.

[–] victorz 3 points 7 months ago

Thank you! I appreciate it. I had a hunch they were sloppy with the term "inertia", and this confirms it for me, assuming I'm understanding it correctly.

[–] prashanthvsdvn 5 points 7 months ago

They are talking about Moment of Inertia. Inertia wrt to rotation changes with how they are positioned in reference to the spinning axis. Think slender bodies are easier to rotate compared to wider bodies with same mass. That’s what they mean when earth slightly flattens out its becoming less slender and more difficult to rotate

[–] db2 16 points 7 months ago
[–] victorz 11 points 7 months ago

This image highlights Baily's deads

lol, I'm not trying to pick on someone with dyslexia but this was a pretty funny typo.

[–] [email protected] 8 points 7 months ago

Sweet, now I get to put "worked with NASA" in my résumé.

[–] [email protected] 3 points 7 months ago* (last edited 7 months ago) (1 children)

I'm honestly confused what they can get with shitty, massively processed smartphone sensors at low zoom. I understand the premise of stuff like radio telescopes distributed over a large area, but the quality of cell phone cameras just isn't that high for anything at any kind of distance.

Even with my Canon 5D Mk3, with a 500mm lens multiplied to 1000mm by a teleconverter, and a solar film to manage how insanely powerful the sun is, the quality just isn't that high:

sun

I'm not seeing what a few hundred heavily processed pixels tell you even if you have a lot of samples.

[–] Harriet_Porber 3 points 7 months ago (1 children)

Earth’s natural satellite can serve as a valuable research partner in measuring the sun’s oblateness. This is due to a phenomenon known as “Baily’s beads,” which are the tiny flashes of light during an eclipse that occur as solar light passes over the moon’s rugged terrain of craters, hills, and valleys. Since satellite imagery has helped produce extremely detailed mappings of lunar topography, experts can match Baily’s beads to the moon’s features as it passes in front of the sun.

The way I'm guessing this works is: Baily's beads will be detectable on shitty cameras since they will be distinct flashes of light, and since we have very detailed information of the moon's topography they can determine information on the sun based on your phone's location and the timing of the flashes of light.

And if that is how it works, that is fuckin rad. A+ science.

[–] [email protected] 1 points 7 months ago

I'd really like to see the modeling on this. My brain just can't compute flashes that are discrete enough and useful enough to serve as data points.

Though once you get into advanced physics my brain starts to melt. And I guess even the idea that they're able to plot the exact angular position to use the topography information is kind of fucking up my head.

[–] [email protected] 1 points 7 months ago

"This item is not available in your country". Too bad, I thought they could use data from Canada but I guess not!