Question

If a galaxy is located 200 million light years from Earth, what can you conclude about the light from that galaxy?

The light will take 200 million years to reach Earth.

The light will travel 200 million kilometers per second to reach Earth.

The light will travel a total of 300,000 kilometers to reach Earth.

The light will travel a total of 200 million kilometers to reach Earth.

Answer 1

what do you think ?

Answer 2

Well it's not C or D because 1 light year alone is 300,000 kilometers. And I don't think it's A, BUT B doesn't sound right either. So I have no idea.

Answer 3

First of all, 1 light year is not 300,000 km, it is about 10 trillion km.

B definition, a light year refers to distance taking by a light in one year. For example, the closest star' distance (beyond the sun) is approximately 4.3 light years. That means, its light will reach to the earth 4,3 year later.

So what do you think now ?

Answer 4

Oh, I read my notes wrong! Light travels at 300,000 km per second (is what I meant.)
So you say the star is 4.3 light years away and so it takes 4.3 regular years to reach Earth?
Then a galaxy that is 200 million light years away will take 200 million regular years to reach Earth. So it would be A?

Answer 5

yes it is.

Answer 6

Thanks so much! I'm really glad that I got someone who didn't just tell me A, B, C, or D. The explanation is MUCH better.

Answer 7

You are welcome! if i had told the answer directly, i would not have learnt something. it is better for me too.