The list of Astronomy planets can be very long indeed. We have many more to discover, including extrasolar planets. The Solar System is still one that astro-greens can appreciate. In fact, it can be fun to learn more about the different outer solar system bodies, and what they are made up of, and which ones are not.
For example, we now know there are two main groups of planets in the Solar System. They are gas planets like our own, and rocky planets like Earth, and each group has many moons. The list of Astronomy planets for this system is quite long indeed. There are extrasolar planets too, but only one – Halley’s Comet – has actually been seen with the naked eye by amateur astronomers.
The first group of planets is the gas planets. They include our own Sun. The second category is rocky planets. These include the planets of the asteroid belt, the icy worlds of the outer solar system, and the rockier worlds like Jupiter and Saturn. One of the first exomoons discovered was the “Galileo” moon, which was found circling Jupiter.
Now, if we take the list of Astronomy planets for our own solar system and extend it out beyond the system of the Sun to include other planetary bodies, we will see a lot of water-bearing planets. This includes Venus, Earth, and Juparana. The “icy” planets (Neptune, Pluto, Uranus, and Pluto) also feature a large number of water-bearing planets.
The second list of Astronomy planets is the rocky planet system. There are no oceans within this system, so all the water is bound to be solid. The list does not include comets, as they are extremely small and do not feature significant gravity. Therefore, none of the objects in this system are capable of having gases pulled from the solar wind. They would not feature a gaseous content at all.
In fact, many of the gas planets in the list of Astronomy planets might be classified as Trojan Planets. A Trojan planet can have a liquid outer atmosphere. These objects can be very similar to Earth’s moons. However, Trojan Planets cannot hold a massive enough moon to receive a gaseous content. Thus, none of the objects in this system could have a substantial amount of an atmosphere.
The third category is made up of rocky “mini-planets”. These objects could be relatively small rocky gas planets in their own solar system or relatively larger rocky gas planets orbiting close to a star in the Solar System. Regardless of the size, these objects would be within the region of the Asteroids. The only way to determine the nature of any such rocky planet is to study it in detail using a telescope.
Even though there is a list of seven specific classes of objects within our solar system, it would be difficult to actually categorize them all. It would also be difficult to determine how many of the objects actually qualify as a gas giant. In any case, the list does serve an important purpose. It allows astronomers to classify and study space closely. It is also useful for teaching kids about space and the laws of our universe.
Of course, the list of planets within the Solar System is not complete without a reference to extrasolar planets. They too are included in the Asteroid category. Although these objects are not classified as gas giants, many of them are likely tidally locked i.e. locked in a stable orbit around a star very similar to the Sun. This means that they will probably not be disturbed by any collisions with rocky debris.
One of the biggest problems when it comes to classifying the planets is making a list that is comprehensive. Although many stars are likely to have many such small objects, it is quite possible that many of the list of potential planets could be wrong. For example, if an asteroid is found to be circling around a star very close to the system it was discovered to be orbiting, the list of potentially terrestrial planets in the Solar System would be very long. Nevertheless, by using the right techniques and software, it is possible to refine the list and give an accurate value for each planet. Astronomy software can make the job of creating a list of planets much easier. Many amateur astronomers and planetarium owners are using this type of software and it has proved to make the job much easier and quicker. It is especially useful for people who may only be able to see a particular star or system a few nights each year. Such individuals would need to check their list of potentially habitable planets each year and then choose which ones to observe based on their relative proximity to the star or system.