This is the "Transit of Venus." Venus and Earth are comparable in size, so the transit of Venus is a good comparison in some ways to the size of Earth in relation to the Sun. Now, realize Earth is further away from the Sun in a place called, "The Habitable Zone" of our Solar System, so the size is actually smaller because of distance.
Venus, the second planet from the Sun, lies, on average, 108 million km from the Sun, about 30% closer than the Earth. Venus is often referred to as our sister planet because of similarities in size, mass, density and volume. It is believed that both planets share a common origin forming at the same time out of a condensing nebulosity around 4.5 billion years ago.
