This began with finding massive planets many times larger than Jupiter, and then eventually finding planets that are rocky - even a few that are close to EarthвЂ™s size itself. Scientists discovered exoplanets, or planets that are outside of our solar system. As telescope technology improved, however, two things happened. Until the 1990s, scientists only knew of planets in our own Solar System and at that point accepted there were nine planets. Since much of the gas ended up in the outer parts of the system, this may explain why there are gas giants - although this presumption may not be true for other solar systems discovered in the universe. That led to the birth of Earth and the other eight planets in our Solar System. As larger balls of matter formed, they swept the smaller particles away and eventually cleared their orbits. Over millions and millions of years, the gas and dust particles became attracted to each other by their mutual gravities and began to combine or crash. ArtistвЂ™s conception of a solar system in formation. Some theories say that the young SunвЂ™s energy began pushing the lighter particles of gas away, while larger, more solid particles such as dust remained closer in. Gravitational attraction at its center eventually collapsed to form the Sun. Today, scientists believe the Solar System began with a spinning gas and dust cloud. As more information comes in, some of our theories of the Solar System must change to suit the new evidence. No human was around 4.5 billion years ago when the Solar System was formed, so what we know about its birth comes from several sources: examining rocks on Earth and other places, looking at other solar systems in formation and doing computer models, among other methods. This article explores the planets in order of size, with a bit of context as to how they got that way. While humans think of Earth as a large planet, in reality it is dwarfed by the massive gas giants lurking at the outer edges of our Solar System. What also is amazing is the sheer size difference of planets. Technological advances in terms of operating aircraft on Mars and propulsion systems provide useful commentary regarding future innovations that will enhance upcoming space missions and the search for life.If youвЂ™re interested in planets, the good news is thereвЂ™s plenty of variety to choose from in our own Solar System.В From the ringed beauty of Saturn, to the massive hulk of Jupiter, to the lead-melting temperatures on Venus, each planet in our solar system is unique - with its own environment and own story to tell about the history of our Solar System. Space probe data related to the Asteroid Belt is also presented.

Key to the existence of life is the evolution of the radiation output of the Sun that is discussed and projected into the future. The search for life on Mars is one of the main objectives of space missions, and it is an ongoing theme of this book. Of particular interest are data that suggest the possibility that life could have existed on the planetвЂ™s surface during its past when MarsвЂ™ atmosphere was wetter and denser.

Recent Mars data and associated observations are addressed in several chapters. The solar systemвЂ™s planets and exoplanets are addressed in an overview manner, and specific space probe data are used to provide a current state of knowledge of Venus and Mars. Solar System Planets and Exoplanets provides a current viewpoint of planetary systems. Of particular interest are data that suggest the.

Solar walk planets