| rdfs:comment | - Space is huge, and the distances involved are far beyond normal human experience. On Earth, if your car breaks down on a country road, you can reasonably expect a rest stop or a gas station within 50 km (ca. 30 miles). Space, however, is not like that country road. If you set your space RV in a randomly-selected trajectory and continue going straight until you get within 50 million kilometers of a star, the chances are astronomically high that you will reach the edge of the galaxy, keep going, and never enter another galaxy... ever. On the off chance you do stumble across a star system, the sheer amount of fuel required to correct your course, match the speed of the star system (since it, too, moves through space), find a safe planet to land on, enter its orbit, and touch down safely would
|
| abstract | - Space is huge, and the distances involved are far beyond normal human experience. On Earth, if your car breaks down on a country road, you can reasonably expect a rest stop or a gas station within 50 km (ca. 30 miles). Space, however, is not like that country road. If you set your space RV in a randomly-selected trajectory and continue going straight until you get within 50 million kilometers of a star, the chances are astronomically high that you will reach the edge of the galaxy, keep going, and never enter another galaxy... ever. On the off chance you do stumble across a star system, the sheer amount of fuel required to correct your course, match the speed of the star system (since it, too, moves through space), find a safe planet to land on, enter its orbit, and touch down safely would be far too great for your jalopy of a ship to handle. This problem exists even for space travel restricted to within a solar system. Planets do not occupy the same place all the time - they orbit their sun. If they don't orbit the sun itself then they orbit something else that orbits that sun. A planet does not occupy its entire orbit at once, either. For example, the position of the Earth during June and the position during December is a difference of 300 million kilometers. A space traveler who doesn't check his Earth calendar might be in for an unpleasant surprise. Add to this the fact that the sun itself is in orbit around the center of the galaxy, and the galaxy is also in motion, and things become rather complicated very quickly. Of course, you could also just find a nearby spaceport, but those tend to be around planets and stars, too - not out in open space - and they are in an orbit you need to get to and then match speed with, just like a planet. A typical low-earth-orbit spot such as the one the International Space Station occupies takes 90 minutes to go around the earth at 27,743 km/h (17,239 mph), but if you're going a little too fast or a little too slow you're going to overshoot/hit or trail it. If you have matched the orbit you could wait until your orbits sync back up, but this could take many, many 90 minute orbits. The above in a nutshell: Nothing in space is ever close, convenient, or in the same place it was a minute ago. This does not deter sci-fi writers, though! A chance to visit a Single Biome Planet or a planet with a dark secret offers far more story options than a spacecraft silently cruising for eternity, running out of power and with a group of mummifying bodies on board. A subtrope of Space Does Not Work That Way and Artistic License Astronomy. A common side effect of Sci-Fi Writers Have No Sense of Scale. A sort of Artistic License Geography, though the term "Geography" isn't usually applied to space because it's so big and different. If characters not only find a planet but land next to what they're looking for see It's a Small World After All. Keep in mind that having Faster-Than-Light Travel would make things conveniently closer, but carries a laundry list of issues of its own. When asteroids are frustratingly close to each other, it's an Asteroid Thicket. Examples of Conveniently Close Planet include:
|
