The Transit of Venus

Yesterday, a rare astronomical event happened: Venus crossed in front of the sun. I was able to see this personally, and several interesting facts occurred to me. First, watch this 3 minute video from NASA. It was recorded by the Solar Dynamics Observatory in orbit above the Earth. Watch in HD if you can.

Let’s start with the sun. In this video, one can easily make out the boiling surface of the sun and the magnetic storms that brighten it with loops of plasma many times larger than the Earth. One can also notice the slow rotation of the sun, as the transit took place over 7 hours. The sun is huge compared to Venus, so Venus must be tiny, right?

Actually, no. Venus is only 5% smaller than Earth and it is the closest planet to us. That’s how big the sun is. Venus and Earth’s orbits differ in their tilt as they go around the sun, so the math works out that this line up will not happen again for 105 years, which is part of what makes this so cool.