Planets in the Solar System
Our solar system consists of an average star we call the Sun, the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. It includes: the satellites of the planets; numerous comets, asteroids, and meteoroids; the interplanetary medium; and the kuiper belt and oort cloud. The Sun is the richest source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun's nearest known stellar neighbour is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years away. 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 we call the Milky Way. The Milky Way has two small galaxies orbiting it nearby, which are visible from the southern hemisphere. They are called the Large Magellanic Cloud and the Small Magellanic Cloud. The nearest large galaxy is the Andromeda Galaxy. It is a spiral galaxy like the Milky Way but is 4 times as massive and is 2 million light years away. Our galaxy, one of billions of galaxies known, is travelling through intergalactic space.
The planets, most of the satellites of the planets and the asteroids revolve around the Sun in the same direction, in nearly circular orbits. When looking down from above the Sun's north pole, the planets orbit in a counter-clockwise direction. The planets orbit the Sun in or near the same plane, called the ecliptic. The former planet Pluto, and many of its Kuiper Belt neighbours are a special cases in that their orbits are highly inclined and highly elliptical. The axis of rotation for most of the planets is nearly perpendicular to the ecliptic. The exception is Uranus, which is tipped on its side.
The SUN
The Sun is the Major energy source of all the Planets in the Solar System, without the sun there is no life.
| "Mankind will not remain on Earth forever, but in its quest for light and space will at first timidly penetrate beyond the confines of the atmosphere, and later will conquer for itself all the space near the Sun". - Konstantin E. Tsiolkovsky |
The 8 Planets
Venus is the second planet in the Solar System, and it’s an almost virtual twin of Earth in terms of size and mass. Venus orbits at an average distance of 108 million km, and completes an orbit around the Sun every 224 days.
Earth is our home; the third planet from the Sun. It orbits the Sun at an average distance of 150 million km. Earth is the only planet in the Solar System known to support life.No planet in the Solar System has been studied as well as Earth, both on the ground and from space. Thousands of spacecraft have been launched to study the planet, measuring its atmosphere, land masses, vegetation, water, and human impact.
Earth has only a single moon… the Moon.
Mars the 4th planet from the Sun is Mars, the second smallest planet in the Solar System. It orbits the Sun at an distance of 228 million km. You might think Mars is large, but it’s a tiny world, with about half the diameter of Earth, and just 1/10th the Mass.
Jupiter is the biggest planet. It’s so large, in fact, that it has 2.5 times the mass of all the rest of the planets in the Solar System combined.
Saturn is the 6th planet from the Sun, and the second largest planet in the Solar System. It orbits the Sun at an average distance of 1.4 billion km. Saturn measures 120,000 km across; only a little less than Jupiter.
Uranus, the 7th planet from the Sun. It orbits the Sun at an average distance of 2.9 billion km. Uranus measures 51,000 km across, and is the 3rd largest planet in the Solar System.
Neptune is the 8th and final planet in the Solar System, orbiting at an average distance of 4.5 billion km from the Sun. It’s the 4th largest planet, measuring about 49,000 km across.
