Ask Tsana

Confused about something I blogged about? Want to know more about a particular topic? Wondering just how long that colony spiralling into the black hole will last?

You've come to the right place!

Just use the comment form below to ask me any questions, be they scientific, fictional or science fictional (or just maths you can't get your head around). I will answer them on the blog first chance I get. If I don't know the answer, I'll try to find out or point you in the right direction.

37 comments:

  1. Hi, there.

    I'm new to your blog and unsure if you've covered this before. I did try going through your tags and stuff but couldn't seem to find anything on the topic.

    I'm trying to come up with a simple (haha) and plausible way to destroy a planet to kick things off for a story but am having trouble getting the science right.

    One of the first sites I visited to figure this out was this Geocide site: http://qntm.org/geocide

    Under the Geocide in fiction page (http://qntm.org/fictional), the author says, "The Sun Crusher is a relatively small ship which carries a small number of missiles, each of which is tough enough to shoot into the centre of a star and cause it to go nova, which would certainly annihilate any nearby Earthlike planet."

    My question is, don't stars that get massive enough to go nova have brief lives and thus not live long enough for a habitable planet to develop? I'm just basing that on Wikipedia (http://en.wikipedia.org/wiki/Planetary_habitability#Massive_stars), though, so I was wondering if you could tell me more. Can the habitable zones of massive stars ever actually be inhabited (and then later die in a supernova)?

    Thanks so much, and more power to you and your writing.

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    1. Ah, after rereading, I see you on this in "The Galactic Habitable Zone," under "The parent star." (http://tsanad.blogspot.com/2011/07/galactic-habitable-zone.html) Should I just delete these comments? :s

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    2. Oh no, don't delete your comments! There are lots of ways to destroy a planet, for various definitions of "destroy". It's definitely worth writing a dedicated blog post, especially since planet-destruction is such a staple of SF. I'll try and get a blog post done soon, within a couple of days.

      Thanks for your question. :-)

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    3. In case you haven't seen it, I posted an answering blog. http://tsanad.blogspot.com/2012/03/destroying-earth.html

      As well as answering your questions, it's about destroying the Earth/a planet generally. Hope it's helpful and feel free to ask more questions :-)

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  2. I love that you have an Ask Tsana section. I don't have a question (right now) but I've been telling everyone that they better check their facts with you before making sci-fi jokes of themselves! xx

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    1. Thanks! :-) And tell them that just because I haven't been updating frequently (life too busy to think of what to post about) I will still answer questions promptly.

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  3. Love the views of Jupiter from Ganymede and Io. How large would it appear from Europa or Callisto? And how large exactly would the sun appear? (I know tiny as hell, but another lovely picture would be amazing.)

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    1. Great question! Give me a few days to photoshop some images -- life's a bit hectic at the moment ;-) In the meantime, you can read about how to calculate those sizes on this post: http://tsanad.blogspot.se/2011/02/foreign-skies.html

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    2. Thanks for the fast reply and link. That math is beyond me haha.

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  4. I actually have another question too that you may be able to help with. It has to do with time and travel. If we could travel at 10% the speed of light throughout the solar system, would that have any real noticeable effects on aging? And would people living on other planets/moons age differently due to differences in their host world's gravity and velocity?

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    1. I've posted an answer to your first question here: http://tsanad.blogspot.se/2012/06/other-foreign-skies.html.

      As for your second question, see this post: http://tsanad.blogspot.se/2012/02/relatively-faster.html. Doing the maths, at 10% the speed of light, time would pass at 99.4% the speed it does for someone not moving at the sped of light. So for every 1000 years that passed for you in your 10% speed-of-light spaceship, 1005 years would pass on Earth.

      There are no appreciable slow-aging effects from living on different planets/moons. For there to be a significant difference, you'd pretty much need to live near a black hole which has a bunch of other problems associated with it.

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    2. Greatly appreciated. The first link doesn't work. Your site is so helpful with mounds of information. I love it.

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    3. Sorry, had some technical difficulties. It should be working now (same link). Glad you like the blog.

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  5. Aloha from Hawai'i again Tsana! I have a hypothetical question. If in the very distant future we had the technology to terraform, would it be best to terraform Callisto and Ganymede or set up domed bases? Ganymede is suppose to have an ocean similar to Europa, but I'm not sure if that's "world wide". Your thoughts on terraforming!

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    1. Hi again Sam. Sorry it's taken me a little while to respond to your question. I've been too busy to sit down and do it properly.

      I've written a post in answer to your question: tsanad.blogspot.com/2012/07/quick-note-on-terraforming-galilean.html. Hope that helps!

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  6. Hi Tsana.

    I love your blog! It's one of the most wonderful things I've ever accidentally stumbled upon.

    I was wondering... with planets like Europa and possibly Ganymede, who possible have oceans, if humans made future settlements under said oceans, would the pressure from the water above counteract the effects of reduced gravity on the human body?

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    1. Hi Brookelin, great question. I've written a (somewhat lengthy) answer here: http://tsanad.blogspot.se/2012/09/gravity-and-atmospheric-pressure.html. Hope that answers your question!

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    2. Tsana,

      Thank you so much for your response!

      It was the exact opposite of what I wanted to hear, but I think it's so wonderful what you do. Whatever gave you the idea? It's amazing.

      Brookelin.

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    3. What gave me the idea? Lots of poorly researched SF movies and my friends telling me to shut up in the cinema ;-)

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  7. How hard would it be to turn around in space... Say for some reason, Curiosity needed to turn around midflight and return to earth. Would BURNING fuel on some sort of reverse thruster work or would it have to make the trip to Mars, orbit the planet and break orbit to return?

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    1. This is for a picture book that I feel impelled to be at least somewhat based in reality... which may be dumb.

      Thanks so much. :) Love your site, been a lurker for some time.

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    2. Hi Anon. Thanks for the question! In case you check here and don't see it on the front page, I've answered your question here.

      Glad you like the site :-)

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  8. Hi again, Tsana.

    I was wondering - in an alternate universe, what would it take for a species to survive on Mars?

    I know that it has some atmosphere, but not a whole lot. With the pressure being below the Armstrong limit, could there feasibly be large creatures (between collie and bear size) that could survive would have higher thresholds and what would they need to do so?

    If the water on a human's tongue boils in space, would an alien creature in these environments be able to have eyes and mouths?

    What might these species' need to overcome the intense radiation caused by Mars' weak magnetosphere?

    Could bio-genetically enhanced humans ever survive these conditions outside a space suit for periods of time upwards of an hour, but less than a day?

    Are these too many questions? Do you know the answers to any of them, or is this more of a medical thing?

    As always, love your blog! There's so much information here.

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    1. Hi Brookelin,

      Sorry for the delay in replying but I'm in a bit of an internet black hole at the moment. I can't answer all of your questions but I'll have a go in a few days when I have a chance to internetify in more than ten minute bursts.

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    2. Hi again Brookelin. I finally got a chance to sit down and write a response. If you haven't already seen it, you can find it here: http://tsanad.blogspot.se/2012/10/atmospherically-speaking.html. Hope it helps!

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  9. Hi again, Tsana. You are the absolute best. Thank you so much!

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  10. Hi! I'm writing a story which isn't exactly science-fiction, but one of my main characters is an astronomer. I took a couple of introductory astronomy classes several years ago, but as I mostly study language, my knowledge of the profession is limited. Do you know where I can find detailed, accurate information about what astronomers do on a day to day basis? (Extra points if it contains information about how the profession has changed over the course of the last few decades, such as with respect to new technology, and/or is not too technical, but these aspects are less important.)
    Thanks!

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    1. Hi Melissa!

      I just googled "A day in the life of an astronomer" and came up with a few links which pass muster. If you want to ask me some specific questions (I'm an astrophysicist, which isn't very different to an astronomer) I'd be happy to do an interview style post for you. You can either post them here or email me at tsana dot dolichva at gmail dot com and I'll answer them in a blog post.

      Day in the life elsewhere online:
      http://www.iopireland.org/careers/life/page_49343.html
      http://wwdis2010.didymodesigns.com.au/?p=scientist&id=1137&v=pub&pg=1 (gets a bit technical towards the end)
      http://curious.astro.cornell.edu/question.php?number=657
      http://www.ucolick.org/~mountain/AAA/aaa_old/astronomer.html
      http://astrobites.org/2011/07/11/a-day-in-the-lives-of-astronomy-grad-students/

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    2. Thanks a million!

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  11. Hi Tsana,

    My son is constructing a solar system for a science project. He asked me what the weather would be like on his innermost planet, and due to the unusual nature of it, I was at a loss. The planet is about 80% the volume of Earth, about the same density, and orbits its sunlike star at a distance that would place it somewhere between the orbits of Mercury and Venus. It rotates once every 8.22 Earth days...slow, but not tidally locked. So my question is, would such a slow rotation allow for extreme cooling on its far side, or would the extreme heat be dissipated throughout the planet? We surmised it would have an atmosphere heavy in CO2 and maybe SO2? Violent winds due to the movement of atmosphere? And if so, would they be high altitude winds? I think he's hoping for a roasting, perpetually windswept day side and a frozen night side, but I had no idea what the thermal inertia would be like on such a slowly rotating world. I have no idea what the transition zone would be like.
    I suggested he name the planet "Rotisserie".
    Thanks for your thoughts.

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    1. Hi!

      We don't really have a large enough sample of real planets to look at to guess this and the planets we do have (in our solar system) don't necessarily fulfil expectations that calculations suggest. It sounds like this planet could be based on Venus more than anything else. Venus actually rotates very slowly (much slower than you've suggested for Fotisserie) but has very very fast winds. (We usually expect fast winds to be a result of fast rotation.)

      Most of what you've said sounds good except for one little thing. If you have a thick-ish atmosphere (which Venus does and which you sort of need for fast winds to matter), where by thick-ish I mean like Earth's or more, and high winds, then the warmth the day side gets from the sun will be fairly evenly distributed around the whole planet. You can have some variation in temperature but probably nothing as extreme as you've suggested. Venus, to keep using it as an example, has a pretty even temperature all around on the day and the night side.

      I hope that's helpful!

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  12. Hi Tsana,
    What a great blog! I am writing a story set on an extrasolar moon. Please tell me if my assumptions are accurate. I am imagining a system with one big gas giant or brown dwarf orbiting a sun-like star. The big planet is the only one in the system, but it has several moons. I figure that if Jupiter could have four Galilean moons, then a planet 15 times as big could easily have 7 big moons, including one or more that was the size of Earth. The moon is tidally locked to the planet. The planet's year is 6-8 Earth years. Its axial tilt and moon plane of rotation is 20 degrees, so there would be seasons (2-Earth-year-long seasons). If the planet is that big, would there be eclipses every day? Would there be problems with the planet's magnetosphere impacting the moon's atmosphere? Is there a reasonable way to explain how it might not? Thank you!

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    1. Hi! Sorry for my delay in replying, but I've been travelling and subsequently playing catch-up.

      I'm going to break your question up into parts to answer.

      Firstly, there's nothing obviously wrong with your set up. You might want to consider that the main star would have other planets as well (other than your gas giant/brown dwarf, I mean) but that might not affect your story at all.

      If the planet is that big, would there be eclipses every day?
      I assume you mean eclipses from the planet passing between your inhabited moon and the sun? That would depend on how fast your moon is orbiting and how close to the gas giant it is. If it passes "behind" the gas giant, relative to the sun, there will be an eclipse. Whether that happens every time it's on the far side of the gas giant depends on the gas giant's size as well since your axial tilt will mess with alignment a bit. (Basically, that's why eclipses on Earth aren't more common. But the good news (for ease of world building) is that Jupiter (and hence bigger gas giants) is pretty big and even at the distance of the outer Galilean moons Jupiter wouldn't always cause an eclipse, depending on how it lined up. It would on Europa and Io because they're much close and hence Jupiter is bigger in their skies. But you probably don't want to put your inhabited moon quite that close because some weird/dangerous things would happen with the interactions with Jupiter, like volcanoes.

      Would there be problems with the planet's magnetosphere impacting the moon's atmosphere?
      The biggest problems would be if the moon was too close to the gas giant. Io is the the most catastrophic of Jupiter's moons in that respect. But as already discussed you wouldn't want to put an inhabited moon that close. So long as it's far enough away it should be fine. Also magnetic fields depend on a lot of things like the moon's interior composition. Compare (on wiki) the difference between Ganymede and Callisto or Europa.

      A final note, if you're making the planet bigger than Jupiter, keep in mind that the more massive the planet is, the faster the moons will have to orbit. Something to consider with respect to the length of your days.

      I hope this is helpful! Feel free to ask for more clarification if needed :-)

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  13. Hello Tsana,

    I've been reading about cataclysmic vacuum decay in the hopes of finding science that would help me to better understand and describe the theoretical implosion of the universe. I'm wondering about a civilization advanced enough located many light years away from here, who might have observed the Voyager mission, analyzed the data and decided to contact and warn us (in our own language) of our own impending doom. Could a bridge in time and space allow for a gap in time and space hundreds of light years long enough for our civilization to hear the dying screams of another in real time? Could it be possible for communication between two worlds to be two-sided? I am enjoying exploring my ideas on this subject, but I was hoping or your thoughts on what the experience of the impending and certain collapse of our universe might feel like or look like from our perspective on earth.

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    1. Hi Mike,

      Sorry for the delay in replying to your comment, but life has been a bit busy of late.

      I'm not sure what you mean by "a bridge in time and space". Could this be similar to a wormhole? The existence of wormholes at all is currently purely theoretical so connecting two different places in time for instantaneous(ish) travel/communication is no less plausible than connecting two different places in space. Basically, once you've got a wormhole you're probably going to put a location outside of your "light cone" at the other end of it. (Your light cone is everything in the past that you can see and everything in the future that will be able to see you, loosely speaking. Two sufficiently distant places in the same time are already not in each other's light cones.)

      I'm not quite sure what your question (if any) about cataclysmic vacuum decay/the collapse of the universe is, though.

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    2. Hi Tasan, thank you for your response. I have been busy moving across the country and so I am fianlly able to read your response. Thank you! It's a delight to hear back from you.
      Regarding the implosion of the universe, if there was life elsewhere, say on one of those new exo-planets like Kelper 452B for example, and the universe were to implode/collapse or "reel itself back in", what might we be able to observe through a theoretical wormhole. How long might it take for the "collapse of the universe" to be observed by this planet if we could view it destroy the region of space 140 light years away?

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    3. The first thing to remember is that all the exoplanets we've found are actually relatively close by. All of them are inside our own galaxy and not on the other side of the universe. And 140 light years isn't very far away at all, on a cosmological scale. Aside from having different stars and constellations in the night sky, the destruction of the universe would look pretty much the same from Kepler 452b as it would from Earth.

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