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Earth and Moon From an Alien's Perspective
krygny writes "NASA's Deep Impact spacecraft (whose extended mission is called EPOXI) has created a video of the moon transiting Earth as seen from 31 million miles away. Scientists are using the video to develop techniques to study alien worlds. 'Our video shows some specific features that are important for observations of Earth-like planets orbiting other stars,' said Drake Deming of NASA's Goddard Space Flight Center... 'A "sun glint'" can be seen in the movie, caused by light reflected from Earth's oceans, and similar glints to be observed from extrasolar planets could indicate alien oceans. Also, we used infrared light instead of the normal red light to make the color composite images, and that makes the land masses much more visible.'" Here are links to the two videos, one red-green-blue and the other infrared-green-blue.
I wish Sagan could be here to see this.
Edward@Tomato - /home/Edward/ man woman
man: no entry for woman in the manual.
"Qua!?"
Space is largely empty so you can turn off most things and just leave your spaceship alone for the majority of the journey. A few microcalibrations along the way will see you right. Taking off is a lot harder but it's the sort of thing you can practise a lot too so you should be ok with that as well.
Doing something in the alien environment at the other end though, such as a solar system or a planet ... that's really hard. You have to design your craft to be able to deal with thousands of unknown, or known-at-an-extreme-distance, factors. That could well put a travelling alien off coming the last 0.0001% of the journey.
http://twitter.com/onion2k
Huh? Did he just say that habitable planets must have large moons? (I've heard a similar argument before - something about two widely spaced bodies keeping the big one from wobbling too much.)
I'm sorry, I think you're underestimating the survival problems imposed by such vast distances...
A gedanken experiment: Assuming you're right, and the distance isn't that much of a problem, *we* have launched spacecraft which have travelled to and landed on different (far closer) planet(oid)s, I have difficulty believing an alien civilisation that can navigate the truly immense gulf between planetary systems having any difficulty at all with a landing or navigation of a solar system (which is also pretty empty, btw)
You do get to make a billion or so observations of the destination as you're travelling towards it, after all. It's not going to be a complete unknown or anything...
Simon
Physicists get Hadrons!
You're correct that the distances are wildly different, but for some observation techniques that really doesn't matter much. The distance between the earth and the moon compared to the distance to the spacecraft is small enough to be just as negligible. There's no reason why something that works 30 million miles away shouldn't work 30 trillion miles away. The only real differences are the brightness and resolution (well...perhaps some of the spectrum may be reduced by the interstellar medium, but that's a pretty specific factor).
You can't resolve objects at the separation of the moon and earth from 30 trillion miles away, not even with the Hubble or Keck telescopes, and especially not with spectroscopes that can give you clues to what chemicals are present on those bodies. By studying star wobbles an astronomer might infer the presence and mass of a "planet," but that won't tell him if it's really a single planet or a planet-moon system. Look at the video and notice that as the moon crosses the earth, the total reflected light from the earth and moon would be decreased by the ratio of the area covered (about 7%) because the moon is blocking part of it. From that, the astronomer can infer not just the presence of the moon, but the relative sizes of the planet and moon.
Assuming the Space Interferometry Mission goes forward as planned, the astronomer might eventually be able to get a spectrum from the planet without being washed out by the parent star. By watching how the spectrum changes during such transits, they can figure out what elements and compounds (like water) are likely present on the planet, and what ones are present on the moon.
It may sound far out, but it's already being done with exoplanets and their stars, and transits of Pluto and it's moon are how we got a lot of our information so far about those two bodies.
I saw Sunshine and I know what you mean, but this is different. This is REAL. That is what the Earth and the Moon actually look like, it's not a CG simulation.
http://twitter.com/OLDTELEGRAM
My point of view is the exact opposite of yours. I'm not something insignificant. Without me, my world wouldn't be the same - it wouldn't even exist. For me, there's no other world but my world, to you, there are no worlds but the one you're living in, etc.
Also, as soon as you're a part of some system, the system is never the same as it would be without you. And you can't even observe a system without being a part of it and having an impact on it.
When we look up at the moon, it moon looks like a pretty bright, reflective object. But in images containing both the earth and moon, you can see that the moon looks positively dim and dingy compared to the cloud-covered portions of Earth.
That that is is that that that that is not is not.
If you get close enough to lightspeed your time slows down so it becomes feasible to live through the journey. The hard part is the acceleration and deceleration (even if you can produce the necessary thrust you have to consider the maximum force the crew can survive vs the time needed to accelerate at that force). I think once SciFi implementation of regular travel with time dilation has been used in Soukou no Strain (anime), a central theme was the time that passed while the spaceships were travelling at near lightspeed though the implementation of physics wasn't that consistent IIRC.
Justice is the sheep getting arrested while an impartial judge declares the vote void.
That was the stupidest movie since Red Planet [imdb.com].
http://www.sci-fi-online.50megs.com/2006_Interviews/07-08-27_brian-cox.htm
http://en.wikipedia.org/wiki/Brian_Cox_(physicist)
"I've discovered this whole new set of people - science fan boys - that I didn't know existed, really. They're interesting. Their almost fundamentalists, in a way. They are much more pedantic than professional scientists. I just interact with professional scientists most of the time and I must say, I've said this a couple of times now, but I've found the scientists that I like to work with particularly - there's a particular type of person I enjoy working with in science - all those went to see Sunshine and loved it. They thought that the portrayal of the physicist was wonderful and the emotional impact that science can have on you - the real reason you want to be a scientist - they found that really vivid in the film and enjoyed it a lot.
But then I see scientists that I think are dull - w*nkers you could call them [laughs] - who have seen it and didn't like it. I can almost use it as a way of working out who I want to work with. I'd say: "Watch this, and tell me what you think of it". If they don't like it, then I don't want to work with them [laughs].
It's very interesting. These guys that get really pedantic are really, I think, missing the point about what science is all about. It's about precision, when you're doing it. So when you're doing research it's all about precision and attention to detail and that's the difficult bit, and that's what you learn how to do. But deciding what research field you want to do, and having really good ideas about what to go and measure, and what to try and find out, that's a creative process. I think a lot of the pedants kinda miss that.
Like you say, Sunshine is not a documentary. It's trying to just, in an hour and forty minutes, get across a feeling of what it's like - not only to be a scientist, because obviously there's much more in it than that. So, I found it interesting to watch the kind of people that get upset because the gravity is wrong."
With the first link, the chain is forged.
Using simple, non-relativistic math, you would surpass the speed of light by accelerating at a constant 9.8m/sec in just under a year. That means you get to live on your spaceship with simulated earth gravity due to your constant acceleration. That means we don't need to turn the inside of our spaceships into pink goo to accelerate to relativistic speeds within a reasonable amount of time.
The only problem is fuel. How do you power a ship at 9.8m/s^2, or any other 'sizable' acceleration? for that long? And don't forget you also have to slow down, or you won't enter orbit around your target--although in the case of New Horizons, it's designed to blow by Pluto because it's not feasible to conduct a mission that *eventually* puts a probe into orbit around the minor pluplanetoid.
You would be right except relativity is an important factor and cannot be simply excluded. Your example makes the assumption that there are no relativistic effects, which is not correct, hence your conclusion is way off too. D-
Relativity is pretty weak up to very close to c. Even at 98% of light speed, the Lorentz factor (mass increase, time dilation, etc.) is only somewhere around 5. So, allowing for a decent fudge factor, classical physics isn't a half bad assumption.
So, making it to such speeds is not extremely unfeasible (fuel required would be around the same order of magnitude and such). The trade off is really the amount of fuel required to attain a certain speed, and the benefits in terms of time dilation you get.
GAAH! MY PRINTER IS ON FIRE!!! PUT IT OUT! PUT IT OUT!