While the video of Mercury’s transit across the Sun is breathtaking. The small planet even appears as a black disk silhouetted against the bright solar star that our solar system is centered around.

Mercury has the shortest and fastest orbit around the Sun and experiences dramatic temperature changes as it rotates. It is a world of extremes. Explore facts about our solar system's fastest planet.

January is a good month for interesting planetary alignment. You will have a lot going on in the night sky. For most of the month, six out of the eight planets will be visible in the heavens. Mercury ...