Thanks to a rare alignment of planets 250 years ago, we were able to learn for the first time just how large our solar system really is.
Looking for Lava in All the Wrong Places
In 1979 Linda Morabito was processing an image taken by the Voyager 1 spacecraft. It was an image of Io, one of Jupiter’s moons. She discovered what appeared to be a plume of material erupting from Io’s surface. Upon further analysis it was found to be due to a volcanic eruption, as was the first evidence of active volcanism on a body other than Earth. We now know that Io is the most geologically active body in our solar system.
Guardian of the Galaxy
Many people have an emotional attachment to the planet, and feel somewhat offended that the mean astronomers have declared the tiny world to be not a planet. So what about Pluto? Well, it turns out we now know a great deal more about the planet than we did when you were little, and we’ll soon know even more.
Neptune All Night
In some ways, associating Neptune with the night is rather fitting. Neptune is 30 times farther from the Sun than Earth, which means the Sun appears about 1/30th the width of Earth’s sun, and about 1/1000th as bright. That is 400 times brighter than the Moon, but it is hardly what we might consider daylight bright.
Funny
Uranus is often considered the funny planet. Pronounce its name in a particular way and you are reminded of a particular portion of your posterior. But even when given a more civilized pronunciation, Uranus remains a funny planet. Its characteristics are somewhat different from the others, which reveals a violent past.
Biden Time
There’s a newly discovered dwarf planet in our solar system, which was recently announced in Nature. It doesn’t even have a name beyond its designation of 2012 VP113, though it has been nicknamed Biden (after the U.S. Vice President) by its discoverers.
Lord of the Rings
All of the outer planets (and at least one asteroid) have ring systems, but none are nearly so bright and extensive as those of Saturn. Saturn will always be known as the ringed planet.
Good to be the King
Jupiter is sometimes said to be a failed star, with a mass just a bit too small to fuse elements in its core. This isn’t really an accurate description, since the it takes at least 13 times the mass of Jupiter to initiate fusion. However, when compared to the other planets in the solar system, Jupiter is king. Jupiter is 2.5 times the mass of all the other planets combined.
Against the Grain
Yesterday I mentioned that Mars will sometimes reverse its direction of motion in the sky, a phenomenon known as retrograde motion. While Mars has the biggest example of retrograde motion, other planets also undergo retrograde motion. Such a strange variation in motion posed quite a challenge for early astronomers looking for a simple geometric model of the Universe.