Our solar system consists of an average star we call the Sun, the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

It includes: the satellites of the planets; numerous comets, asteroids, and meteoroids, and the interplanetary medium. The Sun is the richest source of electromagnetic energy mostly in the form of heat and light in the solar system.

The whole solar system, together with the local stars visible on a clear night, orbits the centre of our home galaxy, a spiral disk of 200 billion stars called the Milky Way galaxy. The planets, most of the satellites of the planets and the asteroids revolve around the Sun in the same direction, in nearly circular orbits.

According to scientific calculations, the Sun contains 99.85% of all the matter in the Solar System. The planets, which condensed out of the same disk of material that formed the Sun, contain only 0.135% of the mass of the solar system.

Jupiter contains more than twice the matter of all the other planets combined. Satellites of the planets, comets, asteroids, meteoroids, and the interplanetary medium constitute the remaining 0.015%.

The following is an estimated list of the mass distribution within our Solar System. Sun: 99.85%, Planets: 0.135%, Comets : 0.01%, Satellites: 0.00005%, Minor Planets : 0.0000002%, Meteoroids: 0.0000001% and Interplanetary Medium: 0.0000001%.

What is the Interplanetary Space/medium?
Nearly all the solar system by volume appears to be an empty void. Far from being nothingness, this vacuum of "space” comprises the interplanetary medium. It includes various forms of energy and at least two material components: interplanetary dust and interplanetary gas.

Interplanetary dust is said to consist of microscopic solid particles. Interplanetary gas is a tenuous flow of gas and charged particles, mostly protons and electrons which stream from the Sun, and are called the solar wind.

The speed of the solar wind can be measured by spacecrafts and is said to be about 400 kilometres per second in the vicinity of Earth’s orbit.

The solar magnetic field extends outward into interplanetary space; it can be measured on Earth by spacecrafts. The solar magnetic field is the dominating magnetic field throughout the interplanetary regions of the solar system, except in the immediate environment of planets because every planet also has its own magnetic field.

The United States designates people who travel above an altitude of 50 miles (80 km) as astronauts. NASA’s mission control uses 76 miles (122 km) as their re-entry altitude, which roughly marks the boundary where atmospheric pressure becomes noticeable.

In 2009, scientists at the University of Calgary reported detailed measurements with an instrument called the Supra-Thermal Ion Imager (an instrument that measures the direction and speed of ions), which allowed them to determine that space begins 118 kilometres above Earth.

The boundary represents the midpoint of a gradual transition over tens of kilometers from the relatively gentle winds of the Earth’s atmosphere to the more violent flows of charged particles in space, which can reach speeds over (1,000 km/h).

This was only the second time that direct measurements of charged particle flows have been conducted at this region, which is too high for balloons and too low for satellites. It was however the first study to include all the relevant elements for this kind of determination – for example, the upper atmospheric winds.

The instrument was carried by the JOULE-II rocket on January 19, 2007, and traveled to an altitude of about 200 km. From there it collected data while it was moving through the "edge of space”.

The Outer Space Treaty provides the basic framework for international space law. This treaty covers the legal use of outer space by nation states, and includes in its definition of outer space the Moon and other celestial bodies.

The treaty states that outer space is free for all nation states to explore and is not subject to claims of national sovereignty. It also prohibits the deployment of nuclear weapons in outer space.

The treaty was passed by the United Nations General Assembly in 1963 and signed in 1967 by the USSR, the United States of America and the United Kingdom. As of January 1, 2008 the treaty has been signed by 98 states and ratified by an additional 27 states.

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