HeebieMcJeeberson

HeebieMcJeeberson t1_jdx0byy wrote

Reply to comment by ventus1b in If earth was a smooth sphere, which direction would water flow when placed on the surface? by Axial-Precession

For one thing, perfect smoothness doesn't eliminate friction - there's also electrostatic attraction between molecules. Eventually the planet rotating under the water would coax it to move.

But moreover, the atmosphere would be screaming by overhead since it does rotate with the Earth. The atmosphere is chaotic, with zones of different pressures which press down on bodies of water unevenly, creating irregularities that the sideways wind can act on to create waves. This is how wind stirs up waves on calm, smooth lakes and such.

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HeebieMcJeeberson t1_jdnt69n wrote

Reply to comment by IronSmithFE in If earth was a smooth sphere, which direction would water flow when placed on the surface? by Axial-Precession

If the Earth weren't spinning then the water would spread out in all directions, stopping when the surface tension stopped it from getting any thinner. It would be a thin puddle beaded up on the surface. That is, unless the amount of water was enough to cover the whole planet - in that case it would cover the planet to an even depth.

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HeebieMcJeeberson t1_jdlgk5n wrote

Reply to comment by JesseLaces in If earth was a smooth sphere, which direction would water flow when placed on the surface? by Axial-Precession

The rotation will try to fling the water away from the Earth's axis, and the farthest place from the axis is the equator. No matter where you place the water, it will flow toward the equator since there's no terrain to stop it. In the real world, where ocean water is free to flow around, sea level at the equator is actually a little higher than near the poles for this reason.

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HeebieMcJeeberson t1_jaf2eit wrote

Reply to Do Red Dwarfs Provide Enough Sunlight for Plants to Grow? by DevilsRefugee

There are a ton of variables but yes it's possible.

A red dwarf's luminosity is between a tenth and a ten-thousandth of our sun's, so even the brightest ones are dim. But sunlight hitting the planet Mercury is about 7x as bright as on Earth, and we've already observed exoplanets that are closer to their suns than Mercury is to ours. So a planet close to a red dwarf could theoretically get as much daylight as we do.

Also, lots of plant life exists in very low light conditions on Earth - and not just mushrooms etc. growing in caves. Plants under rainforest cover get as little as 2% of full sunlight. That's very much in the range of what plants out in the open could get on a world orbiting a red dwarf.

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HeebieMcJeeberson t1_j2ftpvm wrote

Reply to comment by ArceusTheLegendary50 in What if we kept pursuing nuclear spacecraft propulsion? by rosTopicEchoChamber

The Kurzgesagt video is well produced but surprisingly misleading. The drawbacks it brings up are all based on launching all of our nuclear waste into space, using present-day rockets with today's reliability levels, dedicated entirely to this one purpose, and each carrying the largest possible payload of waste. Most puzzlingly, it dismisses hitting the sun as difficult - as if it's any harder than hitting the moon, Mars, an asteroid, or any other space object we've been hitting consistently for decades. "What goes around comes around" is literally a terrible oversimplification that ignores reality.

The impracticalities the video discusses simply aren't relevant to adding a modest amount of waste to rocket exhaust as I described. But yes I agree that the strawman concept of launching nuclear waste into space on the scale described in the video would be a terrible idea.

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