# Tag Info

1

In the center? Short answer no, long answer yes, but... Orbiting around both? Yes. If you have a binary planet, the two planets orbit a barycenter. A sufficient distance away, this is gravitationally equivalent to a single planet of the combined mass. So you can have a moon orbiting the barycenter of a binary planet system. Another possibility depending ...

5

I'm afraid most of what you're looking for is impossible. A moon can orbit a binary planet system by going around both planets, but never by going in-between them. A "figure-8" orbit is highly unstable because for this to work it would need to be free of any outside interference - no stars, no planets, no other moons - nothing could be anywhere near this ...

-1

Yes it can. And Earth (and any planet) has! And even 2 more "axis", not just one There are such a phenomena wich is called "precession" and "nutation"

1

One of the reasons why you might not come across any relevant neologisms is that the rotation periods of most of the bodies in the solar system that you might actually land on is rather long... using "day" as a shorthand for our terrestrial convention of 24 hour days, Mercury has a 58 day period, Venus 115 days, The Moon 29 days, Europa 3 days, Ganymede 7 ...

6

Yes, it can, but not in our 3D universe (but this is not tagged hard science anyway). It is perhaps better to think about rotation as "in a plane", instead of "around an axis". The plane of rotation has two dimensions - you cannot fit another independent plane of rotation into our three dimensional space, you lack one additional dimension. In a 4D space, ...

1

The term is not dependent on the speaker's current location, so much as the speaker referring to a unit of time based off his native planet/system. So, if "sol" is being used by earth people on mars to refer to an earth day, it would still be sol elsewhere, too. I've always heard "Sol" used to refer to either our sun or our solar system . . . pretty much ...

36

I asked this same question, on the physics stack. The answer is that a body can have only one axis of rotation. Below pasted is the link to the question and the answer I picked. https://physics.stackexchange.com/questions/322200/how-many-different-axes-of-rotation-can-coexist Q: I have questions about rotation. There is a sphere in space. I can ...

0

The easiest way I can think of to explain a tidally-locked planet without extreme differences in temperature between the day and night sides would be through the structure and density of its atmosphere. Let me explain: The atmosphere of a planet can have many different effects on a planet's temperature: highly dense atmospheres can have a runaway greenhouse ...

6

This is over a million times more massive than the Asteroid belt between Jupiter and Mars. To summarize the calculations below, we're not getting to Mars. Gravitational attraction between two masses $m_1$ and $m_2$ (that are seperated by a distance of $d$) is defined by the following equation: $F = 6.67*10^{-11} * \frac{m_1 * m_2}{d^2}$ That annoying ...

8

In the short term the planets Earth and Mars would be subjected to the equivalent of the Late Heavy Bombardment. Initially Earth's skies will be filled with magnificent displays of shooting stars. Well, until dinosaur-killer sized rocks come our way. Basically the surfaces of Earth and Mars will be significantly rearranged. Life will become impossible. ...

5

Fact 1: the space between Mars and Earth is kept clean by those two planets gravitational influence Fact 2: 10 times the mass of Jupiter is a lot, I don't remember it out of my mind but might be enough to trigger stellar formation if made of hydrogen. You have then 2 scenarios in the long term. Scenario 1: Earth and Mars swipe the space faster than the ...

2

Counter Coriolis Effect With Spin Effects The math is a bit beyond me (Nasa has a tool that may help you nail down more exact numbers at https://baseball.grc.nasa.gov/), but it seems plausible that projectiles with a high enough spin rate in an appropriate direction could mostly cancel out the coriolis effect, at least as long as you're firing in an ...

9

Schlock Mercenary has something about shooting in rotating frame references more than ten years ago. https://www.schlockmercenary.com/2008-08-17 Schlock and his commanding officer were shot. Schlock then tried to shoot back and failed. Finally he said "I'm gonna have to walk my shots". In other words, he then included tracer rounds and watched where they ...

3

Smart bullets or smart scopes Already we have smart bullets that can adjust themselves in flight to hit a laser pointed target See smart bullets We also have smart sniper scopes that adjust for distance, compensate automatically for wind as well as the Earth's rotation. See smart scopes We already have the tech today to do just this.

1

I doubt this will ever be seen, being such an old thread...but I had an idea recently, and this thread came up during an intellectually curious search. Space racing could be done really soon, in my opinion, using the same basic theme as FPV drones. Pilots would be on Earth, and have nice equipment which would point to space. A course would be launched into ...

12

Essentially the firearm has a smart sight unit attached. Like modern smart phones, it will need an built in accelerometer and a display (indeed, you could probably write an app for an Android or iPhone today), the accelerometer to determine the spin rate and angular velocity, the app calculating the offset and the display giving you the target information. ...

3

You missed an option, design a gun that gives the bullet an equal and opposite force to the other direction so "dumb" bullets fly stright(ish). I give you the Hop-up - used in airsoft to give a bit more range as it basically creates an "up" force to the pellet during it's flight it shouldn't be too much of an issue designing a spacegun to include a similar ...

24

TL;DR: deflection due to coriolis force depends strongly on the angular velocity of the station. In slow rotating stations (eg. very large ones) coriolis effects on short range engagements will be negligible, but can be significant at longer ranges (eg. 100s of metres). In very fast rotating stations (eg. very small ones) the coriolis effects will be so big ...

4

I thought about a few solutions which might help, but none of them seem to be amazing. use training (effort and requires adaption to every new habitat) 1. Definitely use training. This is amazing. As things are on earth, you can be the lamest couch potato ever and use a gun to go out and kill loads of ninjas. Guns are so overpowered. In your ...

2

The obvious answer is you extract hydrogen. You can use it along with oxygen in fuel cells, or rocket fuel, or for fuel in a fusion reactor. Fusion reactors make the most sense in my opinion. You need hydrogen-3, which is rare hydrogen isotope. You won't have to transport massive amounts of hydrogen, you'll get the most energy and since hydrogen-3 is rare, ...

4

Moons of gas giants tend to be tidally locked. They are also tidally heated. So there you have it. Go for thermal energy. Alternatively: if you can build teleporting gates, what is keeping you from building a Dyson sphere around your star? Ditch the gas giant and go for the mother lode.

0

Uranus. Slower escape speed among the 4 gaseous giants of the Solar System. Attractive feature: helium-3 and deuterium to produce semi-aneutron fusion The energy density of this fusion is on the order of 353 trillion joules per kg. The deuterium-helium-3 fusion produces 24% of the X-ray energy '' 20% '' and 4% in neutrons, leaving 76% of the 353 trillion ...

0

Instead of a reflective layer of aluminium, you can technically use the principle behind gradient optical fibre and use multiple films of transparent materials to guide the laser along the surface of the hull and redirect it. The gradient has to be such that no matter what angle the laser hits, it would work.

0

I think if you build the ship wall out of retroreflectors, with a layer of high melting point material below, then you've got the perfect defence against attack lasers. Any laser directed at your hull will be, to a large percentage of the energy, directed right back to the attacking ship. And the layer below makes sure that the heat from what gets absorbed ...

1

The thing that kills lasers at range is beam spread. A laser spreads a lot less than, say a flashlight, but it does spread. That makes the energy density go down. It is the energy density that burns through a ship. If the energy density isn't enough to damage the hull, it just heats the target and, as you pointed out, you lose the heat war. So, things ...

2

Here is a link to a somewhat similar question: How would an astronaut conclude he's on Earth, but 600 million years in the future?1 And you may note that my answer includes another method of telling that they have reached a distant future and the universe is noticibly older.

0

Which laser? There are many kinds of lasers available with wavelengths from radio "masers" all the way to ultraviolet "excimer" lasers, potentially more available with technological progress. And there is no known material that fully reflects all these wavelengths. For example, aluminium does have a dip in its reflectivity in the infrared 700nm – 900nm ...

1

It's been my assumption that a laser would be an effective weapon at short enough ranges that a pulse can vaporize hull plating. "Short range" is a tricky thing to quantify. It very much depends on your own tech level assumptions and requirements, and as you haven't communicated them to us then I can't really speculate. The shorter the wavelength, the ...

2

In the moment before her shuttle entered the gateway, its sensors recorded light coming from the other end and created a snapshot of star positions. The light captured in that snapshot started its journey through the gate 570 million years prior to the moment she entered the gateway. Comparing that snapshot to sensor reading from the moment she emerged ...

2

Wallpapering spaceship with 2-5 mm aluminum (steel would be much better) and active cooling will save you from any reasonable laser if you keep your distance. 80% dissipating energy is only for laboratoy lasers. For powerfull "battle lasers" only 0.1% - 5% of energy goes to the beam. And the beam itself greatly looses energy density with range due to ...

-1

If she's 570 million LY from home, she has bigger immediate problems than what time it is. Like where she is, and how to get back. Whatever instruments she has that will allow her to plot location, her biggest immediate problem, will also indicate that time dilation effect. But having been sucked through a wormhole, working out the date is the least of ...

2

Reflective surfaces will always help deflect some of the power, however no material is capable of reflecting 100% and some of that energy will always be absorbed. So even if you have a 99.99999% reflective surface, you still absorb a tiny bit of energy which is the main point. A laser is powerful because it can focus a decent amount of energy into a very ...

6

It depends on the power that is being fired at you. Conventional mirrors are not 100% reflective. They normally reflect a bit more than 90% of the impinging light, meaning that around 10% of that power is absorbed or transmitted. If you are targeted with a mW laser, 10% of that are peanuts, and you don't have to worry. If you are targeted with a petawatt ...

3

Answering only the first question: Yes, it is a realistic way. Precision may be questionable however (so, she will figure out she is a few hundred million years ahead in time, but won't be sure whether it's 500M or 600M, if we presume present-day understanding of CMB, universe expansion and all the relevant stuff, and Planck-level precision of measurement. ...

7

You have a few conceptual problems here. If you have to cover 570 million light years at 0.9999999999c, time dilation will habe a factor of 0.00014141979198682754. You can use this calculator to find out, just multiply your input by 100 because the calculator uses percentages. 0.00014 of 570,000,000 years is about 79,800 years. That's 12 orders of ...

1

Star Position In that time the stellar map would had changed noticeably. The board computer wouldn't recognize his position and a estimate of time passed could be obtained comparing your map and the actual position of diferent constellations at the point you emerged from the wormhole.

2

Magnetic confinement seems to be a fairly common suggestion and would work in the technical sense, but the amount of energy actually required to magnetically confine an asteroid worth (over the lifetime of the "mine") would be extraordinary. This is particularly concerning given that the containment field would not only have to contain the antimatter under ...

2

The IPM near Earth is 5 particles/cm^3. If we assumes this is 5 hyrdogen atoms we won't be far wrong. First, lets do some Feynman math to see how plausible this is. Everything is about as dense as water, give or take an order of magnitude. A water-density object that weights 1000 tonnes (or $10^6$ kg) is going to be about 10 meters on a side. Solar ...

3

Manipulate dust with electric field First, shield the asteroid from further interaction from interplanetary matter as explained by other answers. Then, make it electrically charged using positrons. We can make positrons (anti-electrons) even with today's technology because they are product of one type of radioactive decay. Then, if there is any surface dust,...

2

This really doesn't seem feasible. I don't have hard numbers, but matter/antimatter annihilation is so incredibly energetic that this object wouldn't really have its own trajectory. any deviation in speed from the background medium would immediately be corrected by the increase in collisions on the front side. that means the object almost certainly wouldn'...

10

One thing which other posters have not mentioned is the effects of the interplanetary medium on the asteroid and mining operation. Before you can do anything, it would be very wise to "clear" the area around the asteroid. A massive "wake shield" in an orbit slightly ahead of the antimatter asteroid will create a zone of extremely hard vacuum behind it, and ...

5

You're not really mining, more like controlled exploding. There is no real extraction just cutting off usable chunks. to do that you just throwing normal particles at it, a superfine stream of low pressure hydrogen will cut this thing like a high power laser through styrofoam. An electron gun or ion gun will cut better than any laser for very little energy ...

8

How exactly would one go about mining an asteroid made of antimatter? In short: Laser ablation to blow off parts of the object. The laser can be put in orbit around the body, without physical contact with it. Channel the plasma to the "box". The produced plasma can be channeled via a suitable magnetic field into a magnetic storage. Again, no physical ...

14

Similar question but with a moonfull of antimatter. Is it realistic to have a moon made of antimatter? My proposition there: Cut some chunks off. You can do this using a laser. In the linked moon scenario you would have to blast stuff up and away from the moon because it would be too dangerous to approach. Your smaller chunk is more tractable in that ...

3

Unfeasible due to frame challenge If the thing is coming into the solar system, it is in a flyby trajectory. Deceleration due to contact with the interplanetary medium will reduce its velocity in two directions: Radial out: this will rotate the orbital path, but not change it enough to have an apoapsis (and therefore cause a capture); Retrograde: this can ...

1

Yes, but it requires an engineered solar system, it can't occur naturally. 1) Your central body needs to be a fairly massive black hole, not a star. Note that this means bright jets heading along it's axis of rotation--this should be vertical or close to it as those jets will sterilize your world if they should cross it. A thick atmosphere is recommended ...

0

The planet is a part of a binary star system. It orbits one star in a plane which is perpendicular to the line connecting the stars. This way the other star will always be over one pole of the planet.

1

On Earth, much of Antarctica's cold climate is due to Antarctic Circumpolar Current, and much of Europe's warm climate is thanks to the Gulf Stream. You can conveniently combine the two - open ocean along the equator with a strategically positioned archipelago diverting warm waters northwards (and inland through conveniently placed straits) while keeping ...

0

2in1 planet We know, that sometimes galaxies "colide" (not like car crash, but like two flocks of birds flying different directions) There were many natural nuclear reactors on Earth burning for many millenia (or even much longer) not all stars are equal, not all planets are equal So have some two galaxies cross its ways, that just some solar systems on ...

1

SHORT ANSWER: This is a difficult problem for those the least concerned with scientific plausibility. At the end of a long discussion I come up with a reasonably plausible planetary set up - though it is so unlikely to occur naturally that a writer might want to have characters speculate that an advanced civilization actually arranged the planets that way....

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