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Huh... OK, thank you, Hutch, but as you said, that's nothing to do with my question. I would have been able to calculate your answer myself without the need to ask here. Only that it's not an answer to my question, not even if a "back-of-the-envelope" roughly approximate answer using a...

Well... that: Please, could you please assist me in obtaining a rough estimate of the distance from the Sun at which a planet resembling Venus or a hypothetical Venus-like planet (for the sake of simplicity) would have a habitable-zone surface temperature? A "back-of-the-envelope" educated...

This is not for any kind of homework ---the last time that I went to school was 30+ years ago. However, I am a curious person, I've been asked by other people who know that I love science and I need to calculate this: As you will most possibly know, a misreading of this paper by the media...

Yes I have, and I didn't find anything useful. That's why I came to ask. Indeed. Yep, that's the kind of info I found ---useless without the discharge time. Also in volts, in amps... but never in joules or anything that let me calculate the joules. :frown:

Hi! I would be interested in properly referenced data about the most powerful / energetic lightning bolts on Earth to get a good idea about their maximum possible order of magnitude (maybe depending on location?) Both direct measurements or indirect but well-founded estimates (e.g. satellite...

Hi! I was watching satellite pics of the Earth and I noticed that continuous cover clouds can be really large. So... I felt curious and my question is obvious: Please, does anybody know how large can a cover cloud be on planet Earth, or at least a few of the largest measured ones? (Not...

Hey, thank you, I didn't know this! Would you please tell me more or point me to further reading about it?

Hi! After watching a couple videos about the explosive reaction of sodium in freshwater and seawater, I felt curious and wanted to calculate how much energy is released. However, my Chemistry is super rusty and I think that my result is way too high (equivalent to almost 2 g of TNT per gram of...

Thank you again, Dave. :smile: This part was especially important for me. I didn't want to pass for an ignorant just by asking, "Hey, what if that big guy had another moon or a couple of them?" and be slammed with an avalanche of, "Are you silly?! That is totally impossible because of this...

Thank you very very much again, Astronuc. :smile::smile: That is exactly what I needed to know. Well, it seems to be a NASA or NASA-affiliated idea, originally based on one of several Soviet concepts for a "Venerakhod", so I lend it some credence, but sure you'll be able to discern it better...

Hi, Dave, thank you very much. Yes, I fully agree that: Indeed. However, my question (in my mind, at least...) was more like, "If it had happened, do we have the tools to learn or deduct that it did? What are those tools? Or would it be immediately obvious because this-and-that?"

Hi! I'm fascinated by the apparent "concentration" of the four large Galilean moons in a barely 1.5 million km "strip", and the vast, "empty" distance to the next moons (moonlets?) Out of a purely aesthetic sense of horror vacui, :wink: I've always wondered if there was at least another Jovian...

Thank you very very much, Astronuc, this is exactly the kind of thing that I had it mind. Just one (key) question, please: I didn't understand this, my knowledge is limited as I said. :frown: And it's obviously very important. Would you be so kind to explain it "for dummies", please? Yes...

Fully agreed. I'll leave the specific engineering details to the geniuses. :smile: But, if it would conceptually work, couldn't it be used to Stirling-refrigerate a chamber and keep the electronics and other stuff protected there or the like?

Hi. I'm just a curious person with high-school-level scientific knowledge. However, I was wondering if a specially-engineered Generation IV high or very high temperature (800-1,000ºC) nuclear reactor could work in Venus using the local atmosphere at 450ºC as "coolant", just like a "typical"...

Thank you very much, Merlin. I was reading a bit more about this and now I'm wondering if I've inadvertently described a pinhole camera?

That's why I said "in an opaque material": Just imagine a small hole drilled in a wall, or a metal sheet, or a cardboard, or whatever.

Thank you, Dave. Is there any way to calculate it? I'm curious.

This is not for a homework or anything, I'm just a curious person who was wondering... that: how small is the smallest hole in an opaque material that would still allow to see the "world beyond it", using your eye or any kind of existing or prospective technology? (English is not my mother...

Hi, Dave, Well, I have read it in many different places, including that Wikipedia article. Their average albedo seems to be around 0.05, which is really low... ...and that's why I was wondering if there's the possibility of lots of "non-near-Earth" objects orbiting the Sun which are no longer...

Hi! I have read that cometary nuclei have a very low albedo, even lower than coal or asphalt. Because of this, they absorb lots of light and heat rather than reflecting them. So I was wondering how hard is it to detect extinct comets. Could the solar system be full of dead nuclei buzzing around...

Thank you again very much. I honestly thought that this was a common, obvious or even "classical" problem with a "set answer" since there's Calculus because, after all, it's basically the famous Galileo's Tower of Pisa experiment with realistic gravity. I was actually surprised when I didn't...

Thank you very much, Chester! I guess that's #74? But what do the variables r, r0, u, u0 and u1 mean to properly substitute and calculate, please? (I have followed the entire discussion as hard as I could, but as I said, I got lost halfway and by post #75 I wasn't understanding anything...)...

I'm totally unable to do that, Scott. I'm just able to solve stuff like t or v = integral of this-and-that multiplied by this-other-thing, squared. That's why I needed the straightforward equations. Don't worry, I guess this is beyond what I could study too many years ago, I appreciate your help...

Thank you both very much, I really appreciate it, but I am reading that thread and I'm already completely lost. As I said, I'm not a specialist or a student, just a worker with a bit of Sunday free time and lots of curiosity. This was a "Sunday thought", I don't have the time or ability to study...

Hi Chester, thank you very much, I think I would be able to solve such equations. I have searched the forums extensively before posting my question (I also thought that it would be a common question) but I was unable to find it. Would you please be so kind to point me to the appropriate thread(s)?

Hi! I was wondering about an object free-falling to Earth (or wherever) in a vacuum from a very high altitude where g is significantly lower than on the surface: let's say 5,000 km for instance, where g would be 3.08 m/s2 according to the equation gheight = gsurface · (RadiusEarth / (RadiusEarth...

Thank you very much for your (big) patience, Charles, now I'm getting the idea. So I could consider it like sort of a "neutral buoyancy" gas, couldn't I...? [But I still don't understand why a gas which is lighter than air (even if slightly) will not rise (even if slowly!)]

OK, I get that. I still don't understand why, but I get it! :) So, if it was (let's say) "propelled into the air", it would stay up there and would not rise or fall, wouldn't it...? (Until it starts burning, at least!)

Yeah, I got interested in diborane because I was reading about pyrophoric materials and I found it to be the only one which is lighter than air... and I basically wondered if it would rise in flames! :biggrin: (Instead of staying close to the ground and killing someone or something...)

I (think) I understand that one, the density of air is equal to the density of air so it doesn't have any reason to rise, but... why a slightly lighter gas would not...? "Common sense" (yeah, yeah, I know...) would suggest the opposite!

Yes, yes, I know, this, but once we start with the equations... :oops:

Thank you again and I appreciate it a lot, Charles, but... I didn't understand this, so sorry! :sorry: I'm just your average guy with a huge interest in science but I wasn't fortunate enough to get a good education. So to start with, I don't even get why helium will rise (or even what A.W...

Thank you very much, Charles, I'd just need to learn if it would "hug the ground" or even tend to accumulate in low-lying places as some sources say; or if it would rise even if slightly (or tend to stay above ground if already there) as it would be logical given that it seems to have a slightly...

Hi, I have been reading about diborane (B2H6, a gas at standard conditions) and while the sources provide different density values (!), as in 1.2475 g/L at standard conditions, or 1.18 g/L at 15ºC and 1.216 g/L at 25ºC (sounds crazy?), all of them are lower than dry or moist air at the same...

@Bandersnatch Thank you very much! That's what I needed! :)

That's what I meant! I am very interested in this. Please, could you clarify for me if Vega (or the stars around) can be seen during those Northern winter / Southern summer months from any observatory in the Earth (or its nearby orbital observatories) at any time of the day, or is its brightness...

Thank you both very much. I'll try and see if I can get a general idea of the "mesospheric circulation"...

Thank you very much, Bandersnatch! That's exactly what I needed! :smile:

Hi! I guess this question must be easy, but it's driving me crazy: in what time of the year does the Earth "trails" the Sun in its current galactic movement towards Vega? And, could you please confirm that during this period Vega is not visible because it's always facing the "day side" of the...

Yes, I did that, but I'm still unable to see a worldwide map of prevailing directions/speeds (like the one CapnGranite provided for lower altitudes, if not necessarily so sophisticated.) Maybe it's just me being unable to interpret these data, but I "can't see" the mesospheric winds from point A...

Thank you very much, CapnGranite. This is certainly a great tool, but unfortunately it only reaches a height of 10 hPa, which is approx. 30 km, well below the stratopause and the mesosphere. :frown: I need to go higher...

Hi! Please, does anyone know where could I find information or (ideally) global maps with the direction and speeds of the prevailing winds in the mesosphere (if any)? As much as I've tried to, I've been unable to find any source providing this information. Thank you in advance!

Added to my bookmarks! :smile:

Heck, I've always wanted to discover those "South Seas." :wink: Unfortunately it hasn't been possible... by now! :-p

Spain, Eastern Mediterranean coast, very close to that old sea of the Western civilization... :wink:

Quite often. The ITCZ is very much defined by its violent thunderstorms and generally unstable weather: https://en.wikipedia.org/wiki/Intertropical_Convergence_Zone http://earthobservatory.nasa.gov/IOTD/view.php?id=703 ...and aircrafts flying between the northern and southern hemispheres are...

Here they use any http://www.ign.es/ign/head/sismoTipoMagnitud.do [Broken], as defined in the http://www.ign.es/ign/layoutIn/sismoListadoTerremotos.do?locale=es&zona=1&cantidad_dias=5 [Broken], I guess out of convenience. mbLg seems to be quite used, I don't know why. Later they (usually)...

Wow. It's the same earthquake. Here it's been "re-scored" from 4.8 to 5.1 mbLg just a couple minutes ago: http://www.ign.es/ign/layoutIn/sismoDetalleTerremotos.do?locale=es&evid=ign2016ffom&zona=1 [Broken]

A 4.8 mbLg tonight: http://www.ign.es/ign/layoutIn/sismoDetalleTerremotos.do?locale=es&evid=ign2016ffom&zona=1 [Broken] ...among many others: http://www.ign.es/ign/layoutIn/sismoListadoTerremotos.do?locale=es&zona=1&cantidad_dias=5 [Broken] (notice how many "ALBORÁN SUR" are there.)