100% sure it is just an optical illusion. Just like when you see the moon rise vs. The moon overhead. Most people will say the moon at moon rise is bigger. Both are exactly the same size. Try it sometime, hold out a ruler at arms length and measure the moon's width at "moon rise" and then again when it is overhead. Both will measure the same, your brain just makes some false assumptions when the moon is up against the monochrome background of the overhead sky ( appearing smaller, like your 04 coin) vs. when it is near a point of reference like the horizon ( appearing larger, like your 2010 coin)