Mercury is one of The five classical planets and an easy naked eye object. The planets stood out from the other stars to our ancestors because of the way they all moved in regular patterns against the night sky, but Mercury was unique in its rapid motion and the way it never strayed far from the sun. If the planets were to be named for gods, then it was only natural that the flighty mercurial one should be their messenger. … Continue reading →
Jupiter has a mass of about 1.9 x 1027kg – 1900 trillion Trillion kilogrammes. That’s more than double all the other planets, asteroids, comets and dust of the entire Solar System put together. Jupiter is BIG, yet still manages to not weigh anything at all. How? Because it is in orbit around the Sun, just like an astronaut orbits the Earth, and so experiences zero gravity. That’s not to say there is no gravity around Jupiter – it has plenty gravity … Continue reading →
Some time ago, we featured a poster created by the Planerary Society’s Emily Lakdawalla which showed all of the Sun’s largest satellites (or at least, everything we know of that’s bigger than 400km across), to scale. She has since refined the image to correct perspective effects that made Saturn look bigger than Jupiter, and you can see the result to the right. Gas giants, rocky planets, minor planets, asteroids, moons, they’re all there. Click the image to see it in … Continue reading →
As the Earth revolves around the Sun, and the Moon revolves around the Earth, it happens sometimes that all three fall into alignment. When this happens at New Moon, the Moon covers up the Sun in our skies, and we have a Solar Eclipse. It is an interesting coincidence that both the Moon and the Sun appear to be the same size in the sky, since both their actual sizes and their distances from earth are radically different, but this … Continue reading →
