Distance

distance is mesured in 3 differant units kilometers, astronomical units, and light years. kilometers are used mostly to mesure smaller things like the diamiter of bodies. astronomical units (AU) are useually used to find the distance between two planets. light years are mostly to find out biger ranges for an example how long it takes to get from one galixy to another. The basic ratio of light years are 1 light year is equal to 9,460,730,472,580.8 kilometers or sumed up in signtific notation; 9.4605284 × 1015 kilometers

halleys comet as of now is 4,740,000,000 km away from hearth and that would take about 20 years to reach halleys comet from where it is now. Although i don,t think humans would get there because at the rate a comet is moving its distance always will change. So i don't think that humans will ever be able to land non the less go to halleys comet, but we are able to see it from earth every few years.


http://www.youtube.com/watch?v=L1SycRpYH3k