I'm sitting here looking at my can of Dr Pepper on my computer table and I finally had a glimpse of just how large astronomical distances are - and at the same time, how unimaginably huge the Andromeda galaxy is. Let me explain this strange mental link...
The Andromeda Galaxy (M31) is one of our closest galactic neighbors and a member of the Local Group of galaxies. All the stars you see in this photo are actually in the foreground (in our own galaxy), while the dust-like material you see is actually the combined light of billions of individual stars and nebula within Andromeda.
Now let's go back to my Dr. Pepper on the table.
If I move my soda can to the far side of the table, and hold my arm out straight, the can is now just three fingers wide to my eyes. Thats just about how wide Andromeda is in the sky. Now I move the soda to the far end of the room, about 8 feet away and it is now only one finger width across. I can easily imagine how much bigger that can must be if I want it three fingers across. It would have to be 3 times larger. That would be a big can of Dr. Pepper and would certainly keep me awake all night!
Now what if I moved that soda to my neighbors house across the street, and if it was still 3 fingers across it would be a can almost 9 feet wide - and it's just across the street.
What if I moved the can a mile away? Imagine how huge that can would be if it was three fingers across. What about if it was on the horizon, 60 miles away and still three fingers wide? You can start to see how huge things can get with distance.
The sun is 1 finger wide, and lies just under 150,000,000 km away! At that distance, my Dr. Pepper can would have to be 2 1/2 million miles across if it were three fingers wide in the sky!
Now go back to Andromeda. It's width in the sky is three fingers wide, just like my Dr. Pepper but it lies 13,048,795,032,000,000,000 miles away! Anyone want to guess how wide my Dr Pepper would have to be if it was that distance and still three fingers wide?
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