A scientific fact/tidbit you recently learned that you thought was interesting

[Emily's Cat]

Proximity to a star is not essential for liquid water. There are oceans of water under the surface of several of the moons of Jupiter and Saturn, where life might well exist.

But being too close to the star prevents the formation of liquid water, as well as increases the damage from stellar ejections, radiation, etc.

There's a generally accepted "habitable zone" for planets where it's possible for liquid water to form, and thus for life (as we know it) to evolve. Planets need to be close enough to receive enough energy to prompt the formation of complex organic molecules, but far enough away that the formation of liquid water isn't impossible. For red dwarfs, in order to have enough energy to develop complex organic molecules, the planet also has to be so close that it can't form water. There is no habitable zone.

 

[Emily's Cat]

And which could also be happening on moons in the planetary systems of red dwarfs, so such systems could support life. If we rule them out because there would be no planets in the Goldilocks zone, as was suggested, we might be significantly underestimating the number of possible abodes of life in the universe.

Hypothetically, perhaps. But then we're talking about trying to locate the teapot that might or might not be circling Mercury... rather than trying to locate one of several possible teapots at the local antique store.

It's playing the odds. We have limited resources and a really, really, really big universe. Why would we spend effort looking for cases around red dwarfs where outlier conditions capable of producing life might or might not exist... when there are still a whole lot of other stars that we know for sure produce a habitable zone?

 

[lomiller]

Actually, no, not really. Earth receives 44 quadrillion (4.4 x 10¹⁶ W) watts of energy (well, ok, POWER) from the Sun. Earth's core is estimated to produce about 44 terawatts (4.4. x 10¹³ W). That's 0.1% of the energy that comes from the Sun, or about the same percentage of the total energy.

Google seems to agree with you but I think this number is wrong.

Radius of the Earth ~ 6.4*10^6m
This means the earth carves out a spear of 3.14 * 6.4 * 6.4 * 10^12 m^2
or: 129*10^12 m^2
TSI at the top of the atmosphere is ~1370W/m^2

so total power = 1.37*129*10^15 = 1.76*10^17W


The Google answer seems to come from this NASA pdf which says
https://www.nasa.gov/pdf/135642main_balance_trifold21.pdf

The Sun is the major source of energy for Earth’s
oceans, atmosphere, land, and biosphere. Averaged
over an entire year, approximately 342 watts of solar
energy fall upon every square meter of Earth. This is
a tremendous amount of energy—44 quadrillion (4.4
x 1016) watts of power to be exact.

But...
The total surface area of the earth is 5.1*10^14 m^2
342*5.1*10^14 = 1.74*10^17W (same as above)

TSI ~1370 W/m^2 for the part of the earth facing the sun, to find the average over the entire earth you can divide by 4 (area of a Sphere/area of a circle with the same radius) which is where the 342 number comes from. I suspect someone (probably me lol) is applying this conversion incorrectly.

 

[bigred]

Why the latter?

Red dwarf stars last much longer than stars like our sun, so the window of opportunity for life to begin and evolve in such systems would be immense. Earth was already about two thirds of the way through its window when complex life evolved here.

- Highly prone to flares that would wipe out life
- Extremely high emission of x-rays that could sterilize the planet
- One or two other things I forget

 

[bigred]

Well, what I learned recently: Hi, my name is Hans and I'm stupid. A stupid audiophile, to be exact. Turns out that getting a sound card that does 32 bits sampling at 384 kHz makes no difference whatsoever:

Yeah basically anything beyond 24 bit depth and 96kHz sample rate is overkill and in fact higher sample rates are if anything worse. More isn't always better. In fact, odds are you could never tell a diff beyond 24/44.1 for that matter (which is what CDs are made at).

 

[bigred]

Looking up something on stars from this and found that apparently we are finding really....really...cool stars: https://skyandtelescope.org/astronomy-news/the-coolest-stars-ever-found/

And it brought up an interesting point we are reaching of when is it a star and when is it just a really big gas planet? This leads me to think that maybe we should say we have 6 planets, not 8, and two really cool stars in the middle. I mean what's a star? A big ball of gas!

 

[lomiller]

Looking up something on stars from this and found that apparently we are finding really....really...cool stars: https://skyandtelescope.org/astronomy-news/the-coolest-stars-ever-found/

And it brought up an interesting point we are reaching of when is it a star and when is it just a really big gas planet? This leads me to think that maybe we should say we have 6 planets, not 8, and two really cool stars in the middle. I mean what's a star? A big ball of gas!

A star needs to have enough gravity and pressure to fuse hydrogen into helium in their core and Jupiter is too small for that. It would need to be at least 85 times more massive for that.

A science tidbit I learned while checking the minimum mass for a star is that brown dwarfs ~15 - 85 times larger than Jupiter are massive enough to fuse Deuterium and in some cases Lithium but not Hydrogen.

 

[Ziggurat]

Looking up something on stars from this and found that apparently we are finding really....really...cool stars: https://skyandtelescope.org/astronomy-news/the-coolest-stars-ever-found/

And it brought up an interesting point we are reaching of when is it a star and when is it just a really big gas planet? This leads me to think that maybe we should say we have 6 planets, not 8, and two really cool stars in the middle. I mean what's a star? A big ball of gas!

A star should have self-sustaining fusion reactions. I don't think Jupiter and Saturn qualify.

 

[bigred]

I was kidding...but it was interesting to me how the differences aren't as stark as I'd always felt they were. I do still think it's weird to call a big ball of gas a "planet," but I guess the options are limited...it looks like one after all.

 

[Ziggurat]

I was kidding...but it was interesting to me how the differences aren't as stark as I'd always felt they were. I do still think it's weird to call a big ball of gas a "planet," but I guess the options are limited...it looks like one after all.

Trivia for you: the sun and the moon were originally categorized as planets, and Earth was not.

 

[Jack by the hedge]

... In fact, odds are you could never tell a diff beyond 24/44.1 for that matter (which is what CDs are made at).

I suspect you meant 16/44.1 as the CD standard is 16 bit. But your point stands; 16 bits are enough, if the recording is properly mastered to use the full range.

 

[Emily's Cat]

Google seems to agree with you but I think this number is wrong.

That's a lot of numbers and my brain is tired. That said... Off the top, I think you need to adjust for the fact that only half the earth is facing the sun at a time, not the entire thing.

Maybe I'm being overly simplistic?

Radius of the Earth ~ 6.4*10^6m
This means the earth carves out a spear of 3.14 * 6.4 * 6.4 * 10^12 m^2
or: 129*10^12 m^2
TSI at the top of the atmosphere is ~1370W/m^2

so total power = 1.37*129*10^15 = 1.76*10^17W


The Google answer seems to come from this NASA pdf which says
https://www.nasa.gov/pdf/135642main_balance_trifold21.pdf



But...
The total surface area of the earth is 5.1*10^14 m^2
342*5.1*10^14 = 1.74*10^17W (same as above)

TSI ~1370 W/m^2 for the part of the earth facing the sun, to find the average over the entire earth you can divide by 4 (area of a Sphere/area of a circle with the same radius) which is where the 342 number comes from. I suspect someone (probably me lol) is applying this conversion incorrectly.

 

[bigred]

I suspect you meant 16/44.1 as the CD standard is 16 bit. But your point stands; 16 bits are enough, if the recording is properly mastered to use the full range.

Yes, my bad. Of course you will get those arguing the superiority of 24 bit or even 32 24 does give you a better noise floor, but about oh 99.9% of the time even that is overkill and unnecessary.

That said, I record at 24/48. lol

 

[HansMustermann]

That particular tidbit is new to me.

Would moons like the ones in our solar system that might potentially have life, i.e. that circle gas giants a long way out from the star, be as badly affected?

It's fairly new-ish to everyone, scientists included.

Of course, if you're far away enough from the star, you're not going to a be affected as much by a mega-flare. The inverse square law still applies. But we're probably back to the same situation as those moons. They might have liquid water under the ice, and possibly support bacterial life, but probably wouldn't be top candidates for colonization.

 

[HansMustermann]

@lomiller
I suspect that the difference is in the albedo. As they say later in the paper, not all energy from the sun is making it all the way to the surface. Most of it is reflected right back by the clouds, ice, hell, even plants don't absorb green which is why they're green, but also is the spectral peak. Which is also why I didn't just use that cross section.

Of course, since they don't actually show their maths in the paper, it's hard to be sure.

 

[lomiller]

@lomiller
I suspect that the difference is in the albedo. As they say later in the paper, not all energy from the sun is making it all the way to the surface. Most of it is reflected right back by the clouds, ice, hell, even plants don't absorb green which is why they're green, but also is the spectral peak. Which is also why I didn't just use that cross section.

Of course, since they don't actually show their maths in the paper, it's hard to be sure.

~30% of the sunlight that reached is the earth is reflected, but the discrepancy between the two numbers is almost exactly 4X which is exactly the difference between TSI and average insolation across the entire earths surface after accounting for the fact only one side of the earth faces the sun.

 

[Skeptic Ginger]

Looking up something on stars from this and found that apparently we are finding really....really...cool stars: https://skyandtelescope.org/astronomy-news/the-coolest-stars-ever-found/

And it brought up an interesting point we are reaching of when is it a star and when is it just a really big gas planet? This leads me to think that maybe we should say we have 6 planets, not 8, and two really cool stars in the middle. I mean what's a star? A big ball of gas!

I have an image in my head of an astronaut with a Bic lighter about to ignite Jupiter.

 

[pzkpfw]

I have an image in my head of an astronaut with a Bic lighter about to ignite Jupiter.

2010 was 13 years ago.

(https://en.wikipedia.org/wiki/2010:_Odyssey_Two)

 

[Oystein]

That's a lot of numbers and my brain is tired. That said... Off the top, I think you need to adjust for the fact that only half the earth is facing the sun at a time, not the entire thing.

Maybe I'm being overly simplistic?

What counts is the projection of the planet - i.e. the circle that has the same radius.
Remember: The bit of planet surface that is directly facing the sun, i.e. where the sun is in the very zenith, receives 100% of the power, whereas a point where the sun is curretly hugging the horizon (subrise or sundown) is barely getting any wattage at all.
The amount of energy from the sun available to be absorbed by the planet is the amount of radiation within a circle with the circumference of the equator.

 

[arthwollipot]

According to some people, it's possible that the Icelandic Vikings independently invented gunpowder and used it in weapons.

Personally, I'm still a bit skeptical, but here it is:

Viking Atgeirr: Reevaluating the Origins of European Firearms (Forgotten Weapons, 19:24)

 

[Delvo]

If you click the "YouTube" logo in the lower right corner to go to the actual YouTube page for that, you can see at the top of his description that it was an April Fool's Day joke.

It was published on the same day as Jackson Crawford's joke video on the same subject. Jackson Crawford did a much better job of making it clear throughout the video that it was all a joke, which I guess means you could say Forgotten Weapons did a better job of making it seem like it might not be. And JC had done joke videos on several previous April Fool's Days, so his viewers knew what to expect. He's the one who roped collaborators into this.

 

[Delvo]

 

[arthwollipot]

If you click the "YouTube" logo in the lower right corner to go to the actual YouTube page for that, you can see at the top of his description that it was an April Fool's Day joke.

Have I mentioned yet that I think April Fool's Day pranks are stupid?

 

[Skeptic Ginger]

I've seen all those standard model particles, usually lined up in a chart. And I've seen the LHC (Large Hadron Collider) collision images. My brain wasn't ready to go beyond that. Now I am ready for one more step and here it is. (The embed won't play so you have to open the link for the 17 minute video.) The diagrams are excellent and in some cases they show atomic particles in an entertaining way. Also, Dr Matt O'Dowd is improving his speaking style.

https://www.youtube.com/watch?v=TbzZIMQC6vk&t=13s

 

[HansMustermann]

~30% of the sunlight that reached is the earth is reflected, but the discrepancy between the two numbers is almost exactly 4X which is exactly the difference between TSI and average insolation across the entire earths surface after accounting for the fact only one side of the earth faces the sun.

Well, that makes it even worse without the sun, then.

 

[HansMustermann]

I suspect you meant 16/44.1 as the CD standard is 16 bit. But your point stands; 16 bits are enough, if the recording is properly mastered to use the full range.

If it's any defense, my reasoning wasn't about verbatim recording and reproduction. (Even I'm not delusional enough to think that my rips from a 16 bit CD are going to sound better in 32 bit.) My reasoning was that a lot of the time you end up processing and remixing those sounds before reproduction. Like, a game might have footsteps, gun shots, dialogue, my own music as a background, and those are going to be scaled up and down depending on distance (so some will have the amplitude very much reduced, and then combined with some louder ones), have some processing based on environment, and then everything is mixed together. So my reasoning was mostly to have more bits of accuracy for that processing, so not as much error is introduced by those.

 

[rjh01]

I don't see why. Some of those oceans are immense, and unless I'm missing something (which is entirely possible) I would think the conditions that are suitable for life would prevail across fairly large regions of them.

I was thinking life only existing around vents. But if you get enough of them something might evolve that is big and can go from one vent to another eating what they find. These might behave like deep underwater fish do on Earth. But there would need to be enough vents for such a fish to find and go to another without starving. Also there would need to be enough large fish to breed with each other.

And being under water, unlikely to develop technology?

True. Only large predators would need much intelligence and they would be rare to start with. That is, even if they exist (see above). Remember brain power requires a lot of food to sustain it.

 

[Skeptic Ginger]

I was thinking life only existing around vents. ....

The vents provide heat energy but most of the lifeforms rely on chemical energy. So heat and chemical reactions replace photosynthesis.

NOAA - Life on a Vent

Organisms that live around hydrothermal vents don't rely on sunlight and photosynthesis. Instead, bacteria and archaea use a process called chemosynthesis to convert minerals and other chemicals in the water into energy. This bacterium is the base of the vent community food web, and supports hundreds of species of animals.

 

[lomiller]

What counts is the projection of the planet - i.e. the circle that has the same radius.
Remember: The bit of planet surface that is directly facing the sun, i.e. where the sun is in the very zenith, receives 100% of the power, whereas a point where the sun is curretly hugging the horizon (subrise or sundown) is barely getting any wattage at all.
The amount of energy from the sun available to be absorbed by the planet is the amount of radiation within a circle with the circumference of the equator.

Which is what I think I did in my calculation (Note that while I said sphere I meant circle and I did use Pi*R^2 not 4*pi*R^2)

for a circle with the radius of the earth:
Pi*(6.4*10^6)^2 = 1.29*10^14 m^2

1.29 * 10^14 m^2 * 1370W/M^2 = 1.76*10^17W

or if you want to include albedo

1.29 * 10^14 m^2 * 1370W/M^2 * 0.7 = 1.23*10^17W

Radius of the Earth ~ 6.4*10^6m
This means the earth carves out a spear of 3.14 * 6.4 * 6.4 * 10^12 m^2
or: 129*10^12 m^2
TSI at the top of the atmosphere is ~1370W/m^2

so total power = 1.37*129*10^15 = 1.76*10^17W

 

[a_unique_person]

Baby formula is highly inflammable.

https://www.abc.net.au/news/2023-07-11/bomaderry-powdered-milk-factory-fire/102589096

 

[Ziggurat]

Baby formula is highly inflammable.

https://www.abc.net.au/news/2023-07-11/bomaderry-powdered-milk-factory-fire/102589096

Of course it is. Basically any powdered food is, because organic materials burn.

But I do have to add one note:

 

[3point14]

While listening to The Infinite Monkey Cage on my way to work this morning I learned that exercise isn't really that great for weight loss.

I figured I'd need something to back that up, so I found this:

https://www.vox.com/2018/1/3/16845438/exercise-weight-loss-myth-burn-calories

 

[Beerina]

Dr. Dean Edell, who used to host a weekly med analysis show, which I miss terribly, used to say that all the time. If you wanna lose weight, you need to cut calories, not exercise more.

It's not that exercise doesn't work, it's that you get a lot more bang for the buck lopping 1500 to 2000 calories a day off your regular gorging than burning an extra 500 the hard way, which is hard to keep up on top of it.

 

[steenkh]

Dr. Dean Edell, who used to host a weekly med analysis show, which I miss terribly, used to say that all the time. If you wanna lose weight, you need to cut calories, not exercise more.

It's not that exercise doesn't work, it's that you get a lot more bang for the buck lopping 1500 to 2000 calories a day off your regular gorging than burning an extra 500 the hard way, which is hard to keep up on top of it.

The old saying goes “You can’t outrun a bad diet”.

 

[rjh01]

Exercise makes you feel more hungry, so you eat more. If your diet is bad, this means eating the wrong food.

 

[ZirconBlue]

*shrug* I lost a decent amount of weight when I was getting a lot of exercise (marching drum corps), and gained it all back when I stopped.

 

[jadebox]

It's not that exercise doesn't work, it's that you get a lot more bang for the buck lopping 1500 to 2000 calories a day off your regular gorging than burning an extra 500 the hard way, which is hard to keep up on top of it.

Not that I am great at watching my weight, but knowing that it would take 90 minutes of brisk walking to burn off the calories has encouraged me from eating a Snickers bar a few times.

Even though exercise isn't great for weight loss, there is a lot of evidence for it providing better health even for overweight people and that even moderate exercise can help one lose weight - if only because you are not as likely to be snacking on potato chips while walking around the block!

As far as cool science fact, have you ever wondered how the weight gets out of your body when you lose it? It's a silly bit of trivia I ask people about sometimes. You would be surprised, or maybe not, by how many people think you poop it out.

 

[GlennB]

...
As far as cool science fact, have you ever wondered how the weight gets out of your body when you lose it? It's a silly bit of trivia I ask people about sometimes. You would be surprised, or maybe not, by how many people think you poop it out.

Mostly CO2 and H2O, with some N in your pee if you lose muscle mass?

 

[jadebox]

Mostly CO2 and H2O, with some N in your pee if you lose muscle mass?

Yes. Fat is lost mostly through carbon dioxide. So you breathe it out. That helps me understand one reason that losing weight is so difficult.

 

[Ziggurat]

Yes. Fat is lost mostly through carbon dioxide. So you breathe it out. That helps me understand one reason that losing weight is so difficult.

Conversely, most of the mass of, say, a tree comes from the air. Very little comes from the soil, and a bit comes from water, but the majority is air.

In fact, for a C₆H₁₂O₆ sugar molecule created by photosynthesis, the hydrogen is the only part that doesn't come from the air. From looking just at the chemical formula it looks kind of like you strip a carbon from CO₂ and stick it on to the H₂O, but in fact you strip half the oxygen from the CO₂ and all the oxygen from the water to add the hydrogen to the CO. So the oxygen in water used in photosynthesis doesn't become part of the sugar.