The main reason is due to gravity. Just to stay in orbit around the Sun, the Earth and other ...
http://en.allexperts.com/q/Space-Astronomy-Kids-3252/Ga...
We have actually already sent a spacecraft to Halley's comet. During the mid 1980s Halley made one of its visits to the inner solar system and five spacecraft were sent to intercept it. The most famous was called Giotto Since then, we have ...
http://curious.astro.cornell.edu/question.php?number=22...
I guess ``space'' can be considered anywhere there's not a lot of stuff. There's ``space'' at all scales, between planets, stars, galaxies and clusters of galaxies. Most matter objects are part of clustered structures like galaxies (or plan...
http://phy.duke.edu/courses/055/faqs/faq12
Yes,Comets And Meteors are Both In Space.
http://www.blurtit.com/q2556259.html
The comets are particularly important because they, or rather others more or less like them, may have originally provided most of the water and organic chemicals to Earth 4 billion years ago.They provide a key record of what conditions were...
http://stardustnext.jpl.nasa.gov/science/ahearn_inter2....
There are lots of cool hard SF stories along those lines. I remember one (possibly by Asimov or Clarke) about a team of asteroid-miners from Mars who, wanting to make Mars self-sufficient and break away from Earth's water-based dominance, f...
http://www.space.com/common/forums/viewtopic.php?t=1759...
Astronomers know which comets and asteroids pass by us by observing the path or orbit these objects take around the sun. Just like the planets and moons, asteroids and comets have orbits which can be mathematically calculated based on obser...
http://deepimpact.umd.edu/faq4.html#q2