In our Solar System, astronomers frequently divide the planets into two groups — the inner planets and the outer planets. The within planets room closer to the Sun and also are smaller and rockier. The external planets are further away, larger and made up greatly of gas.
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The within planets (in bespeak of distance from the sun, closest to furthest) space Mercury, Venus, Earth and Mars. After an asteroid belt comes the external planets, Jupiter, Saturn, Uranus and also Neptune. The interesting thing is, in some various other planetary solution discovered, the gas giants are actually quite close come the sun.
This renders predicting how our Solar System formed an amazing exercise because that astronomers. Conventional wisdom is that the young sun blew the gases into the outer fringes of the Solar System and also that is why there space such large gas giants there. However, part extrasolar systems have “hot Jupiters” the orbit near to your Sun.
The within Planets:
The 4 inner planets are called terrestrial planets due to the fact that their surfaces space solid (and, together the name implies, somewhat similar to planet — back the term deserve to be misleading since each the the four has vastly various environments). They’re comprised mostly of hefty metals such together iron and also nickel, and have either no moons or few moons. Below are brief descriptions of each of these planets based upon this details from NASA.
Mercury: Mercury is the smallest planet in our Solar mechanism and also the closest. It rotates slowly (59 planet days) family member to the moment it takes come rotate around the sunlight (88 days). The planet has no moons, however has a tenuous setting (exosphere) containing oxygen, sodium, hydrogen, helium and potassium. The NASA MESSENGER (MErcury Surface, space ENvironment, GEochemistry, and also Ranging) spacecraft is currently orbiting the planet.
Venus: Venus was once thought about a twin planet to Earth, until astronomers uncovered its surface ar is at a lead-melting temperature that 900 degrees Fahrenheit (480 degrees Celsius). The earth is likewise a slow-moving rotator, through a 243-day long Venusian day and an orbit approximately the sun at 225 days. Its atmosphere is thick and also contains carbon dioxide and also nitrogen. The planet has no ring or moons and also is right now being checked out by the European an are Agency’s Venus to express spacecraft.
Earth: Earth is the only planet v life together we recognize it, however astronomers have uncovered some virtually Earth-sized planets outside of our solar system in what might be habitable areas of their corresponding stars. It consists of an atmosphere of nitrogen and also oxygen, and also has one moon and also no rings. Countless spacecraft one our planet to provide telecommunications, weather information and also other services.
Mars: Mars is a planet under intense study because it shows indicators of liquid water flowing on its surface ar in the ancient past. Today, however, its environment is a wispy mix the carbon dioxide, nitrogen and argon. It has actually two tiny moons (Phobos and Deimos) and no rings. A Mars job is slightly longer than 24 planet hours and also it takes the planet about 687 planet days to circle the Sun. There’s a small fleet that orbiters and also rovers at Mars ideal now, including the huge NASA Curiosity rover that landed in 2012.
The outer Planets:
The outer planets (sometimes referred to as Jovian planets or gas giants) are large planets swaddled in gas. Lock all have actually rings and all of plenty the moons each. In spite of their size, only two the them space visible without telescopes: Jupiter and also Saturn. Uranus and Neptune were the first planets discovered since antiquity, and showed astronomers the solar device was larger than previously thought. Below are short descriptions of each of these planets based ~ above this information from NASA.
Jupiter: Jupiter is the biggest planet in ours Solar System and spins very rapidly (10 earth hours) family member to that is orbit the the sun (12 planet years). The thick atmosphere is mostly consisted of of hydrogen and helium, perhaps neighboring a terrestrial core that is about Earth’s size. The planet has actually dozens the moons, part faint rings and also a great Red clues — a raging storm happening for the past 400 year at the very least (since us were able to see it with telescopes). NASA’s Juno spacecraft is en route and will visit there in 2016.
Saturn: Saturn is finest known for its influential ring device — seven known rings through well-defined divisions and gaps between them. Exactly how the rings acquired there is one subject under investigation. It likewise has dozens of moons. Its setting is greatly hydrogen and also helium, and also it also rotates conveniently (10.7 earth hours) relative to its time to circle the sunlight (29 planet years). Saturn is right now being checked out by the Cassini spacecraft, which will fly closer come the planet’s rings in the comes years.
Uranus: Uranus was an initial discovered by william Herschel in 1781. The planet’s job takes about 17 earth hours and also one orbit around the sun takes 84 planet years. The mass includes water, methane, ammonia, hydrogen and helium neighboring a rocky core. It has dozens of moons and also a pass out ring system. There room no spacecraft slated come visit Uranus appropriate now; the critical visitor to be Voyager 2 in 1986.
Neptune: Neptune is a remote planet that has water, ammmonia, methane, hydrogen and also helium and also a feasible Earth-sized core. That has more than a dozen moons and also six rings. The only spacecraft to ever before visit it to be NASA’s Voyager 2 in 1989.
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To learn more about the planets and missions, check out these links:
Solar system Exploration: Planets (NASA)NASA Photojournal (NASA)Missions (NASA)Space science (European space Agency)USGS Astrogeology (U.S. Geological Survey)The Solar System and also Its Planets (European space Agency)
CategoriesAstronomy, overview to an are TagsEarth, within planets, Jupiter, Mars, Mercury, Neptune, external planets, Saturn, Uranus, Venus