1 light year is the time taken by light to travel the distance in 1 year (julian or Gregorian whatever). So if a particular planet / star is 100 light years away from earth, does that mean that light travels 100 years to reach earth. In other words whatever I see here from earth now is something that was or happened 100 years before.
A light year is a measurement of distance like a yard or a mile. A light year is the distance light travels in one year. in miles it is about six and a half trillion miles. And yes if a star is 100 light years away it means it took the light 100 years to get here. Any thing you observe is something that happened 100 years ago.
Yup, you are always looking into the past. The speed of light is that slow. 8 light minutes to the sun, 4 light years to the next nearest star, nearly 4 million light years to the next big galaxy over. Light travels at 1 foot per nanosecond.
One year, as you stated. Yes, and yes.
If you see the object on that distance in kilometers even then it would be on line.There are the table with all future eclipse that will be on line of course.Just as comets.
Some of the oldest stars we look at are thousands of light years away Often they have already died
