Little Details

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Entries by tag: ~science: astronomy

Regularly repeating solar eclipses
I am not really sure how to research this.

Is it possible for a planet to exist that would experience repeating total solar eclipses at regular intervals over one specific part of the planet? I'm not sure if I'm phrasing that right, so to use Earth as an example, what would have to change to allow for a total solar eclipse to occur over, say, Germany every 90 days? What other impact would these changes have on the planet?

Lunar phases if the world had two moons.
First time poster here, so sorry if I mess something up.

Setting: a world in sort of just-pre-industrial times, with two moons but one sun; nature-wise a lot like northern Scandinavia.

Search terms used: if the world had two moons, if the earth had two moons, moon phases two moons, lunar phases if earth had two moons

So, my story takes place in a world that has two moons, which I now realize will result in way more complex problems than I was originally expecting. But I think I can handle it based on a couple of nice articles I found on the subject. So, here are the questions I couldn't find answers to:

- Would the moons have to be on different sides of the planets, or could they be closer to each other, like stars? (Assume that they are on about the same distance from earth)
- If they are on the same side of the planet, how would the lunar phases work? Meaning, would they be full at the same time?
- If one of them is closer to earth, would it keep the other one in shadow, depending on where the person watching them is standing?
- If they are on different sides of the planet, would it be possible to see them both at the same time?

Thank you for you help.

Can you have a longer day than night all year?
My story is sci-fi set on a fictional colonized planet. Most of the inhabited area of the planet (not a very large area) is a horrendous desert and I want it to have a long day but a short night. (It's inhabited by humans so it needs a reasonably similar gravity and atmosphere to Earth.) The planet, sometime in its history, was hit by a large meteor, big enough to leave a huge crater, and I was hoping that would be a good enough way to get an erratic orbit. Is it possible to have an orbit erratic enough to create a mostly-stable place for people to live, but have an all-year day/night imbalance? I was thinking something with a wobbly near-tidal lock, but to be honest I don't understand my research well enough to extrapolate whethere it would be possible. It plays in to a lot of my cultural-worldbuilding (do your research before you decide these things, people!) so I'd like to keep it if possible.

Research: orbits, tidal locking, axial tilt, "can you have a longer day than night", etc.

Living in space
Daenerys Stormborn, Khaleesi, Silver Queen, Mother of dragaons, Targaryen
I'm writing a doctor who fic about a pilot traveling in space in a gunship as a minor character.  I'm stuck writing a scene about living quarters in the gunship.

I need the answers for two questions:

1. What are the general living conditions in space and what will happen after prolonged travel in space for more than three years?

2. How does someone take a bath or shower with or without water in space?

I did google this link that talks about using wet towels and foamless shampoos while wearing a cylindrical suit. But I wanted to know more information about having an actual shower in space.

Time periods surrounding the midnight sun [answered]
I am writing a story set in the North near the Arctic Circle (anywhere on the planet, as this is an alternate Earth). The question concerns the natural phenomenon of the midnight sun in general.

I’ve researched “Midnight Sun” “Summer Solstice” “Arctic Circle” etc (which yielded the very interesting fact that living above the arctic circle means you don’t have to mow your lawn as much and references to a Stephenie Meyer book. Which probably just means that I’m terrible at research.)

I also found a lot of information about the midnight sun itself, as in where and when, but my question is really what happens just before or just after? How do you get from permanent light to permanent dark in practical terms? I understand that the midnight sun isn’t just one day but rather a longer period of time? Is there ever a time when there is an extremely short night? How long would the shortest one last? I can’t imagine how it works. The sun dips behind the horizon and then comes back up soon after. Is it actually dark during that time or more of a twilight? And how far away would the earliest point in time be for a night like that in relation to the solstice?

This is my first time posting here. I hope my post and tagging is okay. I’m sorry if the question isn’t very clear. That's probably the reason why I couldn’t solve it with an internet search. Any help would be appreciated.

Thank you.

ETA: Thank you all so much for your very detailed and helpful, not to mention fast, responses. This was exactly what I was looking for. I can't thank you enough. It is very much appreciated.

Somehow pretending the geocentric model is still viable
[Wolf's Rain] *Blinku*
As we all know, the earth revolves around the sun, aka the heliocentric model.

However, let's pretend that, for some reason, in modern society today, people still use the geocentric model, aka the earth is stationary and the sun and everything else revolves around the sun. unfortunately according to my research we don't have to pretend too hard; apparently ~20% of the US/UK/Germany/Russia still think this but let's pretend our education isn't that bad

1) How far into bizarro land will I need to twist the Ptolemaic system to account for various things we know in astronomy (stars twinkling, Galileo's observations, Kepler's laws, etc.)

I really don't care how bizarro I'll need to get; I actually want to create this giant mess, that I can later refute. It may help that my fictional modern society has magic and gods, and Absolutely And Resolutely Believes that the gods raise the sun and moon (and yet for some reason still tries applying the laws of physics to everything else). Right now I'm using the excuse of said magical gods have created a magical veil around earth that allows them to affect how the sun's light and moon's appearance comes into view to an observer on earth, but everything else follows modern astronomy (including the actual fact that the earth revolves around the sun). Also, my fictional society has not gone space age yet and so we don't have to worry about things like the Hubble telescope and satellite information enlightening everyone yet.

2) Other than the brief examples I listed earlier, what are various proofs that shows that the earth revolves around the sun?

Copernicus, Galileo, Kepler (and Newton) are the big ones I know, and a few things like twinkling stars and parallax (which I only vaguely understand), but what other observational proofs are there that show that the geocentric model is really, really dumb? In other words, what holes will still exist in my souped-up bizarro Ptolemaic system, that I'll be able to use to refute it?

I could just use the Ptolemaic system as is with all its "deferents" and "epicycles," but I'm not sure it could still hold with modern society, which has telescopes (Galileo) and things like TVs, cameras, etc. I need a system that modern society, with all of its current knowledge in astronomy, can use - and still have the sun/moon revolve around the earth.

I saw a throw-away reference in one of my astronomy books with some attempts after Copernicus to still have a geocentric model was to have the earth at the center, the sun/moon orbiting the earth, but have everything else revolving around the sun. Would this even work? Would this model fool my fictional society long enough?

ETA: Confession: this is actually for a tabletop game based on an existing canon so I can't change the existence of the gods or the technology level. Unfortunately one of the player characters is an astronomer so now I need to reconcile the two, which obviously the game creators didn't bother with.

Space! On magnatism and communication, and how spaceships navigate and/or avoid colliding with stuff
Writing an 'in space' fic, and I have a couple questions. Some of the story takes place in the Epsilon Eridani star system. Wiki says: "Epsilon Eridani has a higher level of magnetic activity than the Sun, and hence demonstrates increased activity in the outer parts of the star's atmosphere: the chromosphere and corona. The average magnetic field strength of this star across the entire surface is (1.65 ± 0.30) × 10−2 T,[58] which is more than forty times greater than the (5–40) × 10−5 T magnetic field strength in the Sun's photosphere."

My question is (and i've googled this about ten different ways, and can't get anything) is what, if anything, would that do to spaceships in that system (mining craft in the asteroid belts) trying to communicate? Would it be disruptive, or would it not mean much of anything unless you were right on top, so to speak, of the sun? This is assuming the mining craft are using radio waves to communicate. If there's a better option, please mention it.

Second question - how does a spaceship 'see'? In a star system with the aforementioned magnetic activity, and a lot of debris, would radar be sensitive enough? Or would it be overwhelmed by all the 'stuff' out there? The space shuttle is composed thusly: The nose cone made of reinforced carbon-carbon, the the chassis is made of an alloy of titanium, aluminium and vanadium, The windows are main from reinforced polycarbonate. The rest is made of fibreglass and carbon fibre. The tiles are made of silica ceramic tiles or composite absorption tiles. Polystyrene is used for insulation. If the spaceships I'm writing use similar construction, how 'hard' would they be to see on radar, or how easy?

Googled: would magnetic activity affect radio waves in space and got information about what it does to earth, but not in general, and not if there's a limit depending on how close/far you are.

Not sure if the tag is right.

Busting open an airlock in space
Here is the setup. The heroes need to get to their space ship which is in a docking bay on a large space station. The bad guys have it surrounded so the good guys blow open the exterior doors to the bay...

So questions...

Based on MOVIES (since I have never tried this... yet) there is explosive decompression which causes a violent rush of air and blows everyone out of the hanger into space. This sounds great, but is it real? The pressure difference between a pressurized shuttle bay and outside is only 1 atmosphere, does not seem like it would really do that.

Second question, would the size of the hole matter for the wind force? Say a door made for a normal person verse the hanger doors.

Research I have done has been Google searches with various key words such as "explosive decompression," "air lock open in space," and so on. The problem is all the reliable links I found talked about the impact to the body of the sudden exposure to vacuum and nothing about the air velocity blowing or not blowing out. I did not know where to turn after that, so I came here. :)

Resource Post: "Xenology" - A Sci-Fi Writer's 101
Hi, I thought this might be useful for people:

"Xenology - An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence, and Civilization" is the almost complete, free online version of a comprehensive resource book for sci-fi writers and other interested people. It's from the 1970s, so the science isn't entirely accurate anymore (especially fields like biochemistry and exobiology were still in their infancy back then), but I think it's still very useful and interesting. It's written by a guy who now researches nanotechnology and who was involved with SETI and political advocacy for space exploration, so I'm fairly confident he researched this as well as he could back then. I haven't read all of it yet, but judging from the fields that aren't my speciality, it seems understandable enough for laypeople.

From the Summary:

"Topics include the history of the idea of extraterrestrial life; comparative planetology, stars, and galaxies; xenobiology (definition/origin of life, exotic biochemistries, and possible alien bioenergetics, biomechanics, sensations, reproduction, and intelligence); extraterrestrial civilizations (energy sources, biotechnology, interstellar travel, alien weapons, planetary and stellar engineering, xenosociology, and extraterrestrial governments and culture); interstellar communication techniques; and the sociology, legal issues, and appropriate interaction protocols pertaining to first contact."

(Edited for spelling and clarification.)

Light speed travel.
Dopey Scoot
I need some help with this.

Story takes place a couple thousand years from now. Someone develops light-speed space travel. How far, in terms of our own galaxy, could a ship travel in about a five hundred years?

I suspect not very far, but I can't get anywhere close to figuring this out. (It's not quite something that can be googled and it's a little... math-y. I'm pretty bad at math.)

Help is appreciated way in advance.

Planetary orbits in the early 15th century

Can anyone recommend sites which would show the orbits of all planets for 1420 or thereabouts?  (ETA: Comets would be nice, too.)

I've tried Stellarium, Solstation, and Astronomy Workshop. Search terms like “orbits of the planets” “historical planetary orbits” and “planetary orbits fifteenth century” result in the history of the solar system or the history of astronomy - but I just want to know which constellations the planets were in. A specific search using 1420 as a term came up with something way beyond my comprehension.

I've got a fairy slow connection and don't want to shell out for software!

Any help would be greatly appreciated.

ETA 2: it's for a Shakespeare fanfic, so I don't want to make any astrological howlers - but then again, Shakespearean time is kind of fluid, so I've got a wide choice of dates to work with.

Worlds & Weathers [ANSWERED]

Setting: Character gets put into an escape pod and sent somewhere (she doesn't know the location). She lands on a planet where it's frigid and icy and there's sand like a desert everywhere. There's no snow. I suppose there's not enough moisture in the atmosphere to be snow?

Question(s): 1) is it even possible to be below freezing but not even snow?

                         2) is it possible for a place to be extremely cold, icy but the terrain is sandy like a desert?

Granted I know that since I'm writing a sci-fiction novel I could probably just make it so our scientific knowledge is irrelevant or not as advanced but the character is from earth (in this time 2010-2011) so she would compare her knowledge of what her science/her earth can do or can't do. Soooo uhhh. Yeah. Help? :;

Edit/Thanks: Wow I leave this to see what ya'll come up with and I get an entire discussion! Wow. In any case, I know that both of my questions are plausible. And I even got some extra tidbits in extension to my questions! So thank you all for you help and for your input! This is all very helpful and I shall use this as footing to continue to research these subjects, and the things you have directed me to take a look at!

Thank you very, very much! You'll probably see me again though! XD


Does anyone know where I can find a site where the laws of physics are simplified? I'm short on money so buying books is not an option. :(

Also an article that says otherwise about the consistency of the laws of physics throughout the universe~

Asteroid Strike on Earth: How Long to Wait it Out?
Dear folks,

First of all, I wanted to thank you all again for your answers to my question months ago about what sort of planet-solar arrangement we'd have to set up to have colonists experience a three-day-long night next to a fourteen-month-long day. They were all interesting and useful and really helped me get a handle on the question for my book. My book is currently with an agent, undergoing final revisions before we send out to prospective publishers. Please wish me luck.

Secondly, I have a question about another project. My apologies if this question has already been asked. I've searched through the Little Details Livejournal, and while there have been a number of questions about asteroid impacts, my particular questions haven't been answered. I've searched the net and have come up with excellent resources on the immediate impacts of an asteroid strike on Earth. I've also found a fair amount of literature on the KT Extinction, and I've started following Phil Plait's "Bad Astronomy" web site. Again, all excellent resources on what would happen during an asteroid strike, but not as specific on the length of the aftermath. With that in mind, here are my questions.

My project is a YA novel wherein our protagonist (a 16-year-old girl) witnesses the events surrounding an asteroid strike on the Earth. There's no Bruce Willis around to bomb the thing to oblivion, so it's going to hit, and it's as large as the one that did in the dinosaurs.

Let's say that our protagonist is one of a select group that gets swept up and evacuated to a large underground bunker somewhere up north. This bunker has everything they need to survive the coming nuclear winter. With that in mind:

1) How long would they have to wait before enough dust settled out of the atmosphere for them to come out of their bunkers and start some semblance of farming?
2) I have heard it suggested that an asteroid strike in the ocean could seriously deplete Earth's ozone layer, allowing more of the sun's harmful UV rays to hit the surface. How long would it take for the ozone layer to repair itself (I'm assuming much longer than it would take the dust to settle out)?
3) How harmful would the UV radiation be? I know it's cited as a possible factor in the mass extinction, negatively affecting both plant and animal life. Would this make farming impossible, or are there ways to get around this (canvas sheets, perhaps?). Likewise, could the people get by by wearing cloaks with hoods (which I think would be a good effect, having seen "Threads")

I look forward to your responses, and thank you again for being one of the most useful websites on the Internet.

(Update, 12:08): At the mods' request, I've added a subject title like I originally should have [sorry about that], and I should tell you more about the setting of the story. First of all, it's Canada. The protagonist (named Victoria) is a high school student living in small town Ontario, and the bunker is in the north of the province, deep in the Canadian Shield. Probably Sudbury (which has that deep neutrino detector, which, now that I think of it, could be useful in repurposing). The closest asteroid strike (there are multiple ones), is 1000 km south, probably in Pennsylvania.

According to a couple of asteroid impact simulators I checked, the fireball could be seen and felt pretty well instantly, the ground shock waves arrive in around three minutes (but aren't sufficient to do real damage this far out), and the air blast follows around 50 minutes later (strong enough to knock over trees and blow down buildings). So, right now, I'm having the protagonists close the door on the bunker and hunker down for fifteen years.

Thinking this over, I'm wondering if a new ice age might be a pressing issue after that time. In which case, the immediate task upon getting out could be to get to warmer climes, and fast...

Moon problems
pale is the new tan
Hi. It's me again, back with more astronomy questions. This is for a different story, though!

The Backstory

So we're on a planet. Insofar as it supports life, it's earth-like, but I don't care about size or distance from the sun or any of that jazz. (At least not directly.) There's one sun. There're two moons.

The Questions

I need to know what types of configurations these two moons could get themselves into. That is, one of my cultures is very heavily inspired by the moons, and so I need to know how the two moons relate to each other -- do they orbit close together, so they can always both be seen in the sky? Do their phases stay in sync? Does one revolve around the planet much faster, so half the time the moons are both there and the other half it's one or the other?

You're going to ask me for details, and the details don't really matter. I mean, I'd like one moon to be marginally larger than the other (i.e., noticably larger from a planet's perspective), but that's really all I care about. I can make up colors as I go. But I need to know how the phases will work with each other and how the orbits will work.

Also, please keep in mind this is for a fantasy novel, so there will be no space travel or any of that jazz, so specific numbers and fancy words aren't important. (Also, I'm not a math major, but I can handle an equation or two, so if you want to throw a few of those at me, go for it. But remember, I'm NOT a math major, so... )

The Searches

I've searched for various permutations of the words 'orbit,' 'moon,' 'simulation,' and their derivatives. I looked through the astronomy posts here in this community, and while I found a few interesting ones about moons, nothing too specific.

The Plea

Help, basically. Ideally, I'd like to find some sort of lunar simulator, so that I could type in, say, the mass and distance of these moons (which I'd pick arbitrarily) and then see where they are in relation to each other and what they look like to an observer on the planet. I've found things like this for Earth, but the second moon thing kinda effs that simulation for me.

But if such a thing doesn't exist, any sort of generic info would be wonderful. I know virtually nothing about astronomy, besides the bit I've picked up trying to figure all this jazz (and my planetary ring jazz) out. I apologize in advance for being vague and indeterminate... but that comes with not having a clue about any of this. If I need to tell you anything else, let me know and I'll make it up as best I can.


Recovery from thigh injury and a second 'sun'
naughty nice

I attempted to work my way through all of the relevant past posts that might have answered my questions, but may well have missed something in my search, so forgive me if I have! 

Setting: Earth, post apocalypse, so all modern technology etc is gone and has been for generations.

First question!
One male character is stabbed through the thigh by a yari (type of spear), which he survives (no major blood vessels are punctured and the bone is missed), but as the medicine is pretty basic stuff (herbal etc) he isn't going to fully recover all mobility.  The person caring for him knows what he's doing though.  The character is mid-20s, fit and active.
-- My question is how long it would take for him to be mobile enough to walk, with the aid of crutches, and not be in too much pain to do so.  I researched 'thigh stab injuries recovery time' on google but was basically presented with information on thigh muscle strain injuries, the most serious of which, Grade 3, takes several months to recover from.

Second question!
Is is possible to have a second orbiting body around the Earth, far enough away that it doesn't risk colliding with the moon or do too much to make the earth geographically unstable, but big enough to reflect the sun's light during the day?  During winter months we can see the moon in the day, but is it possible to have this all year round with another 'moon' without it being a star in its own right?  My knowledge of physics is pretty basic.  I don't need to know the ins and outs of the actual science, just whether it is possible or not.

Axial Tilt, a Very Long Day and a Short, Short Night
 Setting: an alien planet orbiting a very bright star.

I am working on a science fiction novel set on an alien planet where people can't stand in bright sunlight without suffering horrible burns, and so the society has to exist in shadow. I want the planet's day to be extremely long, so that the time that the sun finally sets becomes a tremendous festival (Nocturne) that lasts the equivalent of two or three Earth days. Solar Maximum -- the equivalent of the planet's noon -- takes place the equivalent of seven Earth months later.

My wife and I are having some difficulty wrapping our head around how (or if) this is possible. We've already established that the colonial cities are polar and are fiddling around with axial tilts to try and produce a long day with a short night. Is this possible? Or should we be fiddling around with something else, making this a seasonal rather than a rotational issue?

I've looked at some papers online and have learned a bit about axial tilt, periodic variations and the effects on climate. What I really need is for someone to update SimEarth to operate on a Macbook, so I can design my planet, tilt its axis and see what day and night become over the course of one rotation.

Any and all comments are greatly appreciated.

Sciences on exploration mission? NOW UPDATED

ETA: Updated with new list, based on comments


I’m currently working on a plot for an Stargate Atlantis fic (set in 2004) and for the plot to work it is important that I know exactly what skills the people that are on the original (season 1) expedition have. I’ve been working on the scientists and other civilians. The expedition consists of 120 people, 40 military and 80 scientists

I’ve been wracking my brain about what kind of skill set would be taken on a scientific mission to an alien city with advanced technique, knowing it will most likely be a one-way trip. They also know they will have to deal with alien cultures. So for I’ve got:

Number of people – specialism (subdived specialisms)



Cut for lenghtCollapse )


The problem:

I have 7 people with some kind of technical PhD, knowing enough about alien technology they can contribute to helping out with serious technical issues. I don’t want to make them astrophysicists as well, but have no idea what kind of technical PhD they can be given


I also have 31 open places for scientists. I am sure I am missing certain fields that would be taken on such an expedition, and perhaps there are too few people in the fields already mentioned.


So, the questions are: what kind of field would the 7 ‘unidentified’ technical PhD’s be in (ANSWERED), and what fields am I missing or do I have too few people for?


The point of the whole exercise is to make the expedition as self-sufficient as possible when they are stranded on an uninhabited world, but keeping in mind they were sent to Atlantis as a scientific exploration mission composed of the best and brightest.

Any help would be greatly appreciated, as I have no idea how to even start googling for something like this, since it’s such a surreal situation.


How good are children's telescopes?
Setting: present day, unspecified location
Previous research: googling, but I seem to come across mostly ebay auctions and really good telescope photos. Not what I'm looking for.

My MC is a young child whose parents bought him a telescope for Christmas, presumably of the kind you buy in Toys 'R' Us for children and not something particularly powerful. He's looking at a strange light (which happens to be an alien spaceship) through it. How well would he see this light? Would he figure out it's a spaceship, or would he be just able to see the light more up-close? It's a silly fic I'm writing so it doesn't need to be extremely accurate, and I can work with the plot either way, but I'd like this to be at least feasible. What if he were looking through a slightly bit better, but still domestic, telescope? Thank you!

Weatherbuilding and Moonsmithing
Of Legend

Right now I'm writing about a habitable planet that is about Earth sized, with one main landmass roughly the size of the Eurasian continent and two small chains of islands roughly the size of the Hawaiian Islands, one just off the southern coast and another several miles east and north. There are two main mountain ranges, both on the western side of the continent, though I'm currently planning on the eastern shore have some cool sheer cliffs to build fortresses on. The continent itself runs from the equivalent of the Tropic of Cancer down to just above the equivalent of the Antartic Circle. There is another continent on this planet at the north pole, which is about as habitable as Antartica. There is one moon, about moon sized.

What I want to know is: what's the weather going to be like? I'm assuming that, with all that water, and very little chance that any storm heading in from the east will hit a big mountain range and break up, that coastline is going to be pretty battered, but let's talk about my background in meteorology!

*cricket chirps, before being run over by a tumbleweed*

Also, I have no idea whether or not it's even possible, but what would cause a moon to be sideways? By which I mean that, rather than have a sickle-shape, it would be more of a smile-shape? I kind of want to say that polar orbit would do it, but let's talk about my background in astronomy!

*crickets mob the tumbleweed, chriping pointedly*


constellations above new york city, and their rotations
all you need is chocolate
setting: new york city, present day (specifically, october/november 2006 to about may 2007, I think? Haven't quite worked out the precise dates yet.)

situation: my character goes to work in a magical store/home(the business is run from the front parlour), located in New York City (Greenwich, I think). Some of the decorating changes automatically with the seasons, ie the trees printed on the hallway wallpaper have their leaves turn, fall, and grow again in the spring. My character's personal room in the house has the ceiling showing the night sky showing directly overhead.

Question: what constellations are highly visible in the night sky above new york city, and do any of them shift position over the course of the year? I basically want my character to look up at the ceiling when she starts work in november, and marvel how easily she can pick out a constellation. Then look up six or seven months later and note that the same constellation has shifted position. Light pollution isn't a factor, and my character's not interested in astronomy at all (though this job might change that), so the more commonly known and easily recognised constellation, the better.

searched: several astronomy books (which only show skymaps for my country), and searched 'constellations+new york city+visible from' - there were a couple of ideas, but nothing specific enough. I found some free skymaps, but they only show the general US continent (nothing specific about NYC), and only this year.

DTA: thanks, everyone! Very helpful, and I think I might see if I can work the Leonid meteor showers in somewhere, too.