Activity for Ilmari Karonen‭

Type	On...	Excerpt	Status	Date
Answer	—	A: Can there be plants on the dark side of a tidally locked world? One possibility could be wind-powered plants. A tidally locked planet with a stable atmosphere must necessarily have powerful winds transporting heat from the day side to the night side. (Ocean currents can also contribute to the heat transport, but you're still going to have a significant temperat... (more)	—	over 4 years ago
Answer	—	A: Blue Cryovolcanic Planet As anyone who's studied inorganic chemistry knows, many salts of copper in the +2 oxidization state have colors ranging from green to a nearly black dark blue, including some remarkably intense shades of sky blue like those of copper(II) sulfate and copper(II) nitrate: Images from Wikimedia Common... (more)	—	about 8 years ago
Answer	—	A: What effects could a hole in a planet have? The Earth is round because it is in hydrostatic equilibrium: its gravity is strong enough, and the material comprising most of its bulk fluid enough, to make it flow into the shape that minimizes its gravitational potential energy: a sphere. As a fairly reasonable analogy, you can think of the Earth... (more)	—	over 9 years ago
Answer	—	A: Suddenly, you live in the dark! The orbit you describe is typical for (moderately) long-period comets. Given the desired orbital period, we can calculate the semi-major axis of the orbit (which, for a highly elliptical orbit like this, is approximately half its maximum distance from the star) using the formula $$T^2 = \frac{4\pi^2... (more)	—	over 9 years ago
Answer	—	A: How far can a time traveller go into the past before his electrical equipment becomes unchargeable? I'm going to take a shot at near-term technology forecasting, and say that your time traveller's near future smartphone and laptop are probably charged over some version of USB (unless they're Apple devices, in which case they'll probably use some more-or-less equivalent proprietary system). The com... (more)	—	over 9 years ago
Answer	—	A: How would two ships travelling at light speed communicate with one another? If the ships really are travelling at the speed of light, using known physics (which is possible, sort of — see below), then they cannot communicate. The reason for this is time dilation: the closer to the speed of light the ship moves, the slower its proper time passes. At the limit of a shi... (more)	—	over 9 years ago
Answer	—	A: Dietary Requirements of Giant Spiders As far as dietary requirements go, there's absolutely no problem with giant spiders. They'd have essentially the same dietary needs as any other large predator, and so any environment able to support, say, wolves or bears or tigers could also potentially support giant spiders of similar size. (In f... (more)	—	over 9 years ago
Answer	—	A: Why aren't animals photosynthetic? From the viewpoint of evolutionary dynamics, the reason why very few species are both autotrophic (photosynthesizing) and heterotrophic (hunting / foraging on other living organism) at the same times is that these two lifestyles tend to require quite different adaptations. One notable example is mot... (more)	—	over 9 years ago
Answer	—	A: What kind of event, if any, would knock the moon off its orbit, without destroying it? Hit it with a rock. A big rock. Something like Ceres might do, if you could somehow get it into an orbit that hits the moon with sufficient relative velocity. Alas, moving Ceres significantly from its current orbit is likely itself a non-trivial task. A stray Kuiper belt object might be more prac... (more)	—	over 9 years ago
Answer	—	A: What efficiencies make a realistic food chain? The 10% conversion efficiency mentioned in other answers is a decent rule of thumb — there's a lot of variation in the real world, but if you assume that the total prey biomass equals somewhere around 10 times the total predator biomass, you'll get a fairly plausible-looking food chain. Tim B ... (more)	—	over 9 years ago