Why can't we see Venus at night but at dawn and dusk?
Welcome to Physics Forum, touqra!
Well, sometimes you can see Venus later than dusk earlier than dawn, but you are correct that, when visible, Venus is always pretty close to those times.
This is because Venus is closer to the sun than Earth. Try this...draw 2 concentric circles...the inner circle is Venus' orbit, the outer circle is Earth's orbit and the sun is a dot in the middle. Now imagine yourself on a dot (the Earth) on the outer circle. Night time is when you are facing outward from the circles (facing away from the sun). Since Venus is on the inner circle, it's harder for you to catch a glimpse of it because it's hidden behind the other side of the Earth that you're standing on.
Mercury is even closer to the sun than Venus and as you would now expect, it's even harder to catch a glimpse of than Venus. Mercury pretty much rises/sets right before/after the sun.
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