- Our solar system is divided into two sections, the first section being the inner planets consisting of Mercury, Venus, Earth, and Mars.
- The inner planets have rocky crusts, dense mantle layers, and very dense cores.
- The second section consists of Jupiter, Saturn, Uranus, Neptune, and Pluto.
- Except for Pluto, the outer planets are gaseous with the outer most layer of gas being hydrogen, they have ring systems, and are much less dense than earth.
- The main differences between the two sections are distance from the sun and the facts that the inner planets are contained by the asteroid belt, where as the outer planets are not.
- With the exception of Pluto, All outer planets are massive in comparison to the inner planets. The smallest outer planet, being Neptune.
- The inner planets are also called terrestrial planets, and the outer planets (excluding Pluto) are Jovian planets. Pluto is excluded because it does not fit the properties of either the Terrestrial or Jovian planets
- All Jovian planets have three layers, and the temperature increases as the depth increases.
- As mentioned before, All Jovian planets have a ring system composed of many little particles that orbit around the planet (very hard to see on some planets). The rings orbit closer to the planet than the planet’s moons. The rings all orbit over the planet’s equators.
- Jupiter is the fifth planet from the sun and is also the largest planet in our solar system and weighs more than twice as much as all the other planets combined. It revolves around the sun every 11.9 earth years but has the fast rotation time of any planet at about 10 hours. Jupiter is about 5 times farther from the sun than Earth.
- As well as being the biggest planet, Jupiter also has the strongest magnetic field in our solar system. Just like on earth interactions between the magnetic field and the planet’s winds cause auroras.
- Jupiter radiates about twice as much heat back out into space as it takes in from the sun. this is thought to be because of the original heat of formation and from concentration due to gravity.
- Jupiter’s Atmosphere is made up of zones and belts. Dark belts are areas of sinking gasses, and bright zones are areas of rising gasses. Between the zones and belts, high-speed winds blow parallel to the equator.
- The most famous feature of Jupiter is the great red spot and is part of Jupiter’s atmosphere. Although Jupiter also has other spots, they appear and disappear frequently, with the great red spot being more permanent. These spots are areas of the atmosphere that are relatively calm compared to the rest of Jupiter’s turbulent atmosphere.
- The first spacecraft to enter Jupiter’s atmosphere was the Galileo probe on December 7th, 1995.
- Saturn is the 6th planet from the sun, has the most visible ring system, and takes nearly 30 earth years for the planet to revolve around the sun. It takes a bit longer than 10 hours to rotate once. Saturn is about 8 times farther from the sun than earth.
- The planet has an oblate shape, which means it’s flattened at the poles and bulges at the equator.
- Similar to Jupiter, Saturn has dark belts of sinking gases and light zones of rising gases, just not as many zones and belts as Jupiter. Also like Jupiter, Saturn gives off more heat back into space than it receives from the sun because it has internal heating.
- Unlike Jupiter, wind speeds on Saturn can reach up to 1,800 km/h
- Saturn the least dense of all the planets and even less dense than water. The planet has 61 know moons orbiting it not including hundreds of moonlets in the moon system.
- Saturn’s magnetic field isn’t as strong as Jupiter’s but is much stronger than the Earth’s.
- Uranus is the seventh planet from the sun and takes a period of 84 earth years to make one revolution around the sun and17.2 hours to rotate once.
- Uranus is close to 19 times farther from the sun than Earth which causes the sunlight the planet receives to be 300 times fainter than earth.
- This resulting in the average temperature on the planet being -200 degrees Celcius.
- Uranus has a weird axis of rotation and orbits the sun on its side. Many scientists believe the planet collided with an Earth-size object in the early history of our solar system.
- In 1986 Voyager two flew past Uranus and noticed that although the planet’s axis of rotation is on its side, its magnetic field is not. This was surprising because, with most other planets, the magnetic field and axis of rotation vary by only a few degrees, in the case of Uranus the variance is 60 degrees. This causes the magnetic field to create a spiral pattern in the solar wind as the planet rotates.
- Neptune is the 8th planet from the sun and is the farthest of the Jovian planets. It takes Neptune about 165 Earth years to rotate the sun and 16.1 Earth hours to rotate once. It is 30 times farther from the sun than Earth.
- Like Uranus, Neptune’s magnetic field is tipped 47 degrees and offset 13, 500 km from its center in relation to its axis of rotation.
- Scientist believes there is a conductive material in Neptune’s center which creates its magnetic field.
- Neptune’s atmosphere is very turbulent with winds over 2000 km/h and a temperature of -225 degrees and is made up of 74% hydrogen, 25% helium, and 1% methane.
Pluto and Charon
- Pluto used to be the smallest planet in our solar system at a diameter of 2700 km (smaller than 7 of the solar system’s moons, including Earths) and the farthest away. Although every 248 years Pluto’s weird orbit brings it closer to the sun than Neptune, making it the eighth planet from the sun for about 20 years.
- Because of Pluto’s odd orbit, its distance from the sun varies.
- Pluto has only one moon, called Charon, which is about half the of Pluto with a diameter of 1200 km. Pluto and Charon as so similar in their mass and properties that scientists consider them a double planet rather than a planet and moon.
- It is believed Pluto’s temperature varies from -210 degrees Celcius to 235 degrees Celcius, and although no spacecraft has ever reached the planet scientist hypothesize it is composed of 70% rock and 30% water.