Final answer:
The image of a galaxy 1 million light years away is how it appeared 1,000,000 years ago because light travels a distance of one light year in one year. This embodies the concept that observing distant objects is akin to looking back in time, which is fundamental in the study of cosmology.
Step-by-step explanation:
The answer to the question 'If a galaxy is 1 million light years away, the image that we take today is a picture of the galaxy when it was how much younger?' is 1,000,000 years. This is because a light-year is the distance light travels in one year through space. The concept of light travel time allows us to see celestial objects as they were in the past. So, the image we see of a galaxy that is 1 million light years away is the image of that galaxy as it was 1 million years ago.
For instance, the Andromeda galaxy, which is about 2 million light years away, is seen as it was 2 million years in the past. Likewise, the most distant known galaxy, being 14 billion light years away, reveals to us the universe as it was 14 billion years ago. This aspect of cosmology opens up immense possibilities for understanding the evolution of galaxies. Through careful observation and study, scientists have the opportunity to explore the universe over vast expanses of time, though such studies come with significant uncertainties.