We now leave the inner, rocky, terrestrial planets (generally not called all of the adjectives at once). Did you know there is more than one asteroid belt? Neither did I. Wonderful what we can find strolling through articles. Anyway, the inner belt is located between Mars and Jupiter. The entire mass of this belt is only about 4% of the Earth’s moon. In reel life (think Hollywood), the asteroid belt is chock full of lumpy, bumpy rocks, wavering in and out of their pathways. In reel life, a lot of the detritus is about dust or sand size, going all the way up to the largest asteroids, Ceres, Vesta, Pallas, and Hygiea., which hold about half of the mass of the belt. Many unmanned space craft have safely passed through the belt. There have been some bumping between some of the asteroids, with the smaller ones being entrained into mini-clusters.
Inner Astroid Belt
The gas giants are next. They are sometimes called Jovian planets (Jove is another name for Jupiter). The inner planets are referred to as rocky, as opposed to the gas planets, which are not big bags of gas (that would be my ex-husband). They do have a (very small) rocky core, but there isn’t a clear cut difference from the atmosphere and the planet - it just get more dense the deeper towards the core one goes. You couldn’t really land on them. So, here is Jupiter, named for the king of the gods, the biggest of the gas planets. It is 1 thousandth of the mass of the sun, but 2.5 times the mass of all of the other planets combined. The bulk of Jupiter is hydrogen, with some helium and traces of other gases. A day on Jupiter is only 9 hours and 50 minutes, but the Jupiter year is equal to 12 Earth years. Multiple moons (at least 63), most named after the Roman gods & persons of more. The biggest moons, Io, Europa, Ganymede, and Callisto, were discovered by Galileo Galilei, so they are also known as Galilein moons. Despite how fast the planet whips around, there is a persistent Great Red Spot, in just about the same place year after year.
Saturn now steps up to the plate. Saturn was a Roman god of agriculture and harvest. He was the father of Ceres, Jupiter, Veritas and others. Saturn’s claim to fame is the huge ring system around it. Oh, and actually ALL of the gas planets have rings, they’re just harder to see. Saturn is the least dense of the planets. If we had a huge pool of water, big enough to drop Saturn in, Saturn would float. Saturn has at least 62 moons, the largest named Titan. Titan is the only moon in our system that has a an atmosphere, but it’s composed of methane & nitrogen. If Titan wasn’t circling Saturn, it would be a planet. It’s the second largest moon (Jupiter’s Ganymede is the largest). A Saturn day is 10.5 Earth hours, & a year is 29.6 years.
On to Uranus! OK, kids, stop snickering. I grew up saying “Your anus” (*giggle) but apparently “Your In us” is preferred. It was named for the Greek primal god of the sky. Both Ūranus and Neptune have been reclassified as “ice planets”. It has 27 known moons, named after Some hakespeare’s & Pope’s characters. Uranus’s year is 30,688.5 Earth years, a day is 17 hours & 14 minutes. It orbits on its side, and is the coldest planet in the system. Uranus was actually seen in ancient times, but thought to be a star. It was discovered as a planet in 1791 by Herschel.
Finally the last planet, Neptune! (God of the sea). Neptune wasn’t discovered until telescopes were available. Just like Earth & Mars are similar, so are Uranus & Neptune. It has the highest sustained winds of the planets - as high as 1300 mph. Whoosh! A day on Neptune is about 16 Earth hours; a year is 164.8 Earth years. There are 14 known moons. One of the moons, Titan, was likely captured by Neptune. It’s probably the coldest world in the solar system. It’s very active, spewing ice and dust.
Tomorrow, the downgraded Pluto, & other stuffs!