# Tag Info

16

YES The answer is the calliope. Basically, pressurised steam is piped through whistles attached to a keyboard. The main differences between a calliope and a pipe organ are pressure and medium. Pipe organs are made, mostly, of wood and thin metal parts. Steam is made almost entirely of water, and hot water at that. The wooden pipes of an organ will ...

16

"Can early astronomers determine the gravity of their planet's “moon” without ever going there?" Of course they can. Our Earth-bound astronomers did, and we know how they did it. The distance from the Earth to the Moon and the size of the Moon were known since the Antiquity. The Moon is close enough that the parallax method works well enough with the naked ...

13

Alright, this is my first answer on Stack Exchange, so let me know if I've made any grave mistakes in my analysis. These numbers are definitely back of the envelope calculations, but they do give a good picture of what's going on in your ship. TL;DR Yes, it will rotate the ship, but it's nothing that the ship's thrusters can't compensate for if your ship ...

11

We wouldn't notice its gravity was gone, we might not even notice the bang. There's not enough of Pluto for it to have a marked gravitational effect on the Earth, according to the tidal force calculation: $$F=\frac{2GM_1M_2d}{r^3}$$ Where: $F$ is the force exerted on Earth by Pluto $G$ is the Gravitational Constant $M_1$ is the mass of Earth $M_2$ is the ...

7

There won't be any humans to have a society. The single Chicxulub Impactor, which caused a mass extinction that included dinosaurs among many others, was about the size of a small city (not a big city). It's devastation was phenomenal - our estimates of a Nuclear Winter are like a day at the spa by comparison. Shattering the moon, which is the only case ...

7

Firstly it sounds like you want to do bottom-up worldbuilding, meaning you want to get the basic science straight first. I would recommend worldbuilding YouTuber Artifexian, as he has a series where he starts with constructing the solar system and has currently reached climate mapping. He breaks down the science to a very digestible minimum. For your ...

7

What matters for breathability is the partial pressure of the gas. According to Dalton law $Partial\ Pressure = Total \ Pressure \cdot volume \ fraction$ For Earth $P_{O_2}=1 [bar]\cdot 0.21=0.21 \ bar$ On your planet $P_{O_2}=1.5 [bar] \cdot 0.055=0.08 \ bar$ That's a tad more than the partial pressure in the Death Zone on Mount Everest at the ...

6

Your planet is traversing an emission nebula. Here is the Orion nebula. By ESO/Igor Chekalin - http://www.eso.org/public/images/eso1103a/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=27880539 Nebulae are interstellar clouds of gas. Some are bright and give off light; these are emission nebula. Orion is a big one; 22 light years across ...

5

Probably breathable but almost certainly dangerous: The recommended 8 hour Ozone exposure is at most 0.1ppm, that's a thousandth of your atmospheric concentration. Given that studies have shown that tiny increases of just 0.001ppm cause notable increases in fatalities this is almost certainly a sizeable problem in a continuous exposure scenario. The other ...

5

This is a surprisingly difficult question to answer... related ones have been asked elsewhere, with few satisfactory answers. Turns out that simple questions like "what is the stellar density in such-and-such a region of space" doesn't often have a very good answer (multiple answers may exist, differing by at least an order of magnitude) let alone more ...

5

Surface gravity is directly proportional with the radius of the planet and inversely proportional with the density of the planet. Now fire up LibreOffice Calc (or your favorite spreadsheet program), and play with the numbers. I suggest to put Earth's radius, surface area and surface gravity as 1 (because your are interested in relative values), but keep the ...

5

Pluto’s gravity has no detectable effect on the rest of the solar system, and its absence will also have no detectable effect. The chances of a fragment striking the Earth depend on exactly how Pluto is destroyed, with the application of how much energy, breaking it into how many fragments, so you’ll need to provide those details. Specifics are addressed in ...

4

1. Tides the moon would not move in the sky and there would be no tides Wrong. The sun provides tides too (albeit smaller ones than our moon), so the sea still rises and falls on a regular cycle. You'll even get variations in tide height depending on the relative angles of the sun and your "moon", though not to the same extent as spring tides on earth. ...

3

SHORT ANSWER: According to my rough calculations, a planet habitable for water based lifeforms vaguely similar to terrestrial life - not guaranteed to be habitable for humans or other lifeforms transported from Earth - could have a surface area a little more than 1.5 times that of Earth, which is rather disappointing. Some other answers also support that ...

3

Steven Dole suggested in his book Habitable Planets for Man the following gravity, mass and radius ranges for planets still maintaining a magnetosphere, plate tectonics, and a nitrogen + oxygen atmosphere. All values will be given relative to Earth. $$M = 0.4 - 2.35$$ $$R = 0.78 - 1.25$$ $$g = 0.68 - 1.5$$ Now you want a big planet, yet you do not ...

3

We don't have a good measure for how much gravity a human being can sustain for a lifetime. We might well find that 1.1 g is too much. Or that we can easily adapt to 2g. We have a little better understanding of microgravity's effects on the human body, but almost none on long term higher gravity. Twice is probably too high, but anywhere from 1.1 to 1.5 ...

3

PART ONE OF SIX: DETECTING THE DISAPPEARANCE OF PLUTO It seems to me that if Pluto is exploded a lot of the matter in Pluto should turn into glowing gases. Thus the total luminosity of Pluto should increase drastically since it no longer merely reflects light but now also emits light. First possibility: So the next time an amateur astronomer looks at ...

3

Simplest case: fire the projectile in radial direction. The sum momentum of the whole system has to stay equal.  \bar I_\text{ship} = m_\text{ship} \bar v_\text{projectile} \\ \bar I_\text{projectile} = m_\text{projectile} \bar v_\text{projectile} \\ \Sigma \bar I = \bar I_\text{ship} + \bar I_\text{projectile} = \text{const.} \\ m_\text{ship,t0} \bar ...

3

So, let's look at the basic reason life exists on Earth: the Goldilocks Zone. This zone is determined specifically by the distance of a planet to its star, given some characteristics of the star (size, brightness, type, etc.). What this means is basically that unless there's a planet(s) that exists specifically to prevent us from having access to sunlight (...

3

In taxonomy, one of the specific attributes used to help determine if a given group of organisms within a genus should be considered a separate species is whether or not it can successfully interbreed with other similar individuals outside that group - as are discrete differences in morphology. Note, by the way, that in science, species is the smallest / ...

2

If you're dealing with constant acceleration, and you aren't interested in orbital mechanics, the basic equation relating how much Time "T" takes to accelerate from Starting Speed "S1" to Target Speed "S2" at Acceleration "A" is: So you can solve for T, like this: and then just plug in your numbers. So if you started at 0 m/s: and the result is close to ...

1

Today, we have examples of some radically different breathing environs. The most unique I know of are breathable liquids, made from specific perfluorochemicals; https://en.m.wikipedia.org/wiki/Liquid_breathing Science-wise, there is nothing preventing a planet from being covered in this stuff, although you’re on your own to figure out a natural process that ...

1

I googled a little something - an actual product that exists on Earth. Now, this product uses a halogen lamp to melt ice, and is advertised to be releasing the same kind of light as the sun. Why did I bring this up? It's because a single wavelength of light won't be enough to melt ice. What you want is a mix of many different wavelengths, as shown by the ...

1

What wavelength of radiation would be the best/most power-efficient choice for penetrating the atmosphere and melting the snow? None. You want the radiation to be absorbed by the snow but not by the atmosphere. To get this information, you just need to compare the absorption spectra of air and snow/water, like it is done in the following chart (source) As ...

1

Other answers have discussed the methods used by ancient, medieval, and modern pre-spaceflight astronomers to discover the distances, sizes, and masses of various astronomical bodies, from which the surface gravity and escape velocity of those bodies could be calculated once Newton published his laws of physics. Here is another type of answer. Any large ...

1

The easiest propellant to make on the moon would be ALICE, or an aluminum nano-power mixed with ice. No need to separate out the oxygen and hydrogen from the water. ALICE Rocket Fuel Tests Another option is to use pure water heated with a nuclear reactor, making a steam rocket. This does not have the specific impulse of hydrogen/oxygen, meaning that it ...

1

The weakest link in this setup is the solar arrays. If they are on the visible side of the Moon, they can be damaged from Earth, or LEO, based lasers, and the lunar colony would have no way to protect them. It is a little more difficult to attack them, if they are on the far side of the Moon, but still they are the most vulnerable. Shooting lots of small ...

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