Summary

• The four inner planets have slower orbits, slower spin, no rings, and they are made of rock and metal.
• The four outer planets have faster orbits and spins, a composition of gases and liquids, numerous moons, and rings.
• The outer planets are made of hydrogen and helium, so they are called gas giants.

The Inner Planets All are solid, dense, and rocky. None of the inner planets has rings. Compared to the outer planets, the inner planets are small. They have shorter orbits around the Sun and they spin more slowly.

The main similarities are that they all have solid surfaces, are fairly similar in size, especially when compared with the Outer Planets, possess a small number of moons and take a relatively short length of time to complete an orbit around the Sun. In space terms, they are also quite close to each other.

The inner planets of the solar system are also called terrestrial planets, and include Mercury, Venus, Earth and Mars. They are mostly made up of silicate rock and metals and have solid surfaces. Earth is the only one of the inner planets to liquid oceans but some believe that Mars once did as well.

The planets Mercury, Venus, Earth, and Mars, are called terrestrial because they have a compact, rocky surface like Earth’s terra firma. The terrestrial planets are the four innermost planets in the solar system.

The inner planets are closer to the Sun and are smaller and rockier. The outer planets are further away, larger and made up mostly of gas. The inner planets (in order of distance from the sun, closest to furthest) are Mercury, Venus, Earth and Mars.

All of the inner planets are solid, dense, rocky planets. The inner planets either do not have moons or have just one (Earth) or two (Mars). None of the inner planets have rings. Compared to the outer planets, the inner planets have shorter orbits around the Sun, but all the inner planets spin more slowly.

Mercury, Venus, Earth, and Mars are the planets closest to the Sun. They are called the inner planets. The inner planets are made up mostly of rock. The outer planets are Jupiter, Saturn, Uranus, and Neptune.

In the inner Solar System, we find the “Inner Planets” – Mercury, Venus, Earth, and Mars – which are so named because they orbit closest to the Sun. In fact, the radius of the entire region is less than the distance between the orbits of Jupiter and Saturn.

Five planets have been known since ancient times — Mercury, Venus, Mars, Jupiter, and Saturn. The first new planet discovered was Uranus. It was discovered by the English astronomer Sir William Herschel in 1781….

PLANET	Mercury
MASS	0.0558
RADIUS	0.381
SURFACE GRAVITY (g)	0.38

Jupiter, Saturn, Uranus and Neptune collectively make up the group known as the jovian planets. The general structures of the jovian planets are opposite those of the terrestrial planets.

The gas giants of our solar system are Jupiter, Saturn, Uranus and Neptune. These four large planets, also called jovian planets after Jupiter, reside in the outer part of the solar system past the orbits of Mars and the asteroid belt.

four planets

Humans could land at the poles of Mercury – Mercury doesn’t have a dark side – but it has regions at the poles of eternal darkness inside craters in the polar regions. Also could dig tunnels below the surface of Mercury – indeed live almost anywhere there if you build a shelter.

Saturn

Saturn has 82 moons. Fifty-three moons are confirmed and named and another 29 moons are awaiting confirmation of discovery and official naming. Saturn’s moons range in size from larger than the planet Mercury — the giant moon Titan — to as small as a sports arena.

Neptune

Scientists have observed four rings around Jupiter. They are made of small bits of dust, which makes them very faint and difficult to see unless they are backlit by the Sun. In fact, they were first discovered only fairly recently, by the Voyager I spacecraft in 1979.

Ceres, the closest dwarf planet to the Sun, has no moons.

Saturn’s

Sadly, the Earth doesn’t have rings like Saturn, and it probably never did. It might have had rings of rock and dust for periods, but they weren’t that majestic to look at. In fact, seeing rings around the planet would mean we’d lost a moon, and our planet was about go through a period of bombardment. I’ll pass.

The consequences of a second moon orbiting the Earth depend on how massive that moon is and how far from the Earth it orbits. The most obvious effect would be that the ocean tides would be altered. Tides could be either smaller or higher and there could be more than two high tides per day.

Earth’s hypothetical rings would differ in one key way from Saturn’s; they wouldn’t have ice. Earth lies much closer to the sun than Saturn does, so radiation from our star would cause any ice in Earth’s rings to sublime away. Still, even if Earth’s rings were made of rock, that might not mean they would look dark.

No sunscreen would prevent you from getting toasted by two suns. The Earth’s orbit could be stable if the planet rotated around the two stars. The stars would have to be close together, and the Earth’s orbit would be further away.

This diagram compares our own solar system to Kepler-47, a double-star system containing two planets, one orbiting in the so-called “habitable zone.” This is the sweet spot in a planetary system where liquid water might exist on the surface of a planet.

First planet with three suns may have been discovered. A wobbly ring of dust around a triple solar system 1,300 light-years away may have helped astronomers find a rare planet. Forget about Luke Skywalker’s fictional “Star Wars” home planet Tatooine and its two suns.

Meanwhile, the orbits of the planets in our solar system would be thrown into complete chaos. Our planets have stable orbits because they orbit a single massive body, the sun. With three suns, and three massive points in space constantly changing their positions, all of these orbits would be disrupted.

The doctrine of the Three Suns (Chinese: 三阳; pinyin: sānyáng) or three stages of the end-time (Chinese: 三期末劫; pinyin: sānqímòjié), or Three Ages, is a teleological and eschatological doctrine found in some Chinese salvationist religions and schools of Confucianism.

After more than half a century of speculation, it has now been confirmed that Earth has two dust ‘moons’ orbiting it which are nine times wider than our planet. Earth doesn’t have just one moon, it has three.

That’s just how many we’ve found so far. There are likely to be many more planetary systems out there waiting to be discovered! Our Sun is just one of about 200 billion stars in our galaxy. That gives scientists plenty of places to hunt for exoplanets, or planets outside our solar system.