Universe Fact: Solar System

Who Had "Discovered" planets outside our solar system ?

Marc Rayman At Age 14 meets astronomer peter van de kamp(center),who had "Discovered" planets outside our solar system .On the right is radio astronomer grote reber.(image from sky and Telescop,aug.1971.) So although scientists, philosophers, writers, and people like you who have been fascinated by the universe have thought about other solar systems for centuries, they haven't had any to study. When I was young, this was one of many topics that I spent a great deal of time wondering about. In fact, when I was in the ninth grade, I was lucky enough to meet an astronomer who thought he had detected two planets around Barnard's Star, one of the closest stars to our solar system. It was quite a thrill for me to meet someone involved in such exciting work. Alas, later evidence suggested his conclusions were incorrect, but I learned a great deal about the subject, as well as about the scientific method, by studying what this impressive astronomer had accomplished.

The Solar System

Solar System

The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury.

The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest planets, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.

Structure Of Solar System

The order and arrangement of the planets and other bodies in our solar system is due to the way the solar system formed. Nearest the Sun, only rocky material could withstand the heat when the solar system was young. For this reason, the first four planets-Mercury, Venus, Earth and Mars-are terrestrial planets. They're small with solid, rocky surfaces.

Meanwhile, materials we are used to seeing as ice, liquid or gas settled in the outer regions of the young solar system. Gravity pulled these materials together, and that is where we find gas giants Jupiter and Saturn and ice giants Uranus and Neptune.

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