SOLUTION: The Great Galaxy in Andromeda (also known as the Andromeda Galaxy or M31) is about 2.5 million light years from Earth. When we look at this galaxy today, we see light that has been

Question 181893: The Great Galaxy in Andromeda (also known as the Andromeda Galaxy or M31) is about 2.5 million light years from Earth. When we look at this galaxy today, we see light that has been traveling through space for 2.5 million years; i.e. when we look at the Andromeda Galaxy, we are seeing it as it was about 2.5 million years ago! Think about this, we are looking back in time.

1 light year is the distance that light travels in 1 year. Speed of light is 300,000 kilometers/second, find the distance that light travels from the Andromeda Galaxy to Earth in kilometers and express it in scientific notation.
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
The Great Galaxy in Andromeda (also known as the Andromeda Galaxy or M31) is about 2.5 million light years from Earth. When we look at this galaxy today, we see light that has been traveling through space for 2.5 million years; i.e. when we look at the Andromeda Galaxy, we are seeing it as it was about 2.5 million years ago! Think about this, we are looking back in time.
1 light year is the distance that light travels in 1 year. Speed of light is 300,000 kilometers/second, find the distance that light travels from the Andromeda Galaxy to Earth in kilometers and express it in scientific notation.
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The distance is 2.5 million light years.
The speed of light is 300,000 km/sec = 3E5 km/sec (3E5 = 3*10^5)
3E5 km/sec * 60 sec/min * 60 min/hr * 24 hr/day * 365 day/year
= 3E5*60*60*24*365 km/year (notice all the other units cancel)
= 3E5*9.4608E7 km/yr
= 2.83824E11 km/yr (this is 1 light-year)
To Andromeda:
2.83824E11 km/ly * 2.5E6 ly = 7.0956E17 kms, or 7.0956*10^17 kms
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Actually, I think it's 2.2 million light years, but it doesn't matter.
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