Depends on the planet. Mercury is made of mostly iron and nickel (70%/30% I think) Jupiter is gassous - and has no hard surface like Earth.

All sorts of things, but generally speaking there are rocky planets (like Mercury, Venus, Earth and Mars) and gaseous planets like Saturn, Jupiter and Uranus. The rocky ones have some kind of solid core and surface. They may or may not have a molten region like the earth does. The gaseous ones might have some kind of solid core, but predominantly they are made of clouds of gas. Jupiter, for example is just a mass of gasses of varying densities...

Most of the planets in our solar system consist primarily of hydrogen and then helium. The larger gas planets are mostly those elements, but might have sparse, very low precentages, of other elements. The smaller 4 inner planets are made up of many many different elements. Our planet of course has all the elements with some more in abudant then others. Such as large amounts of hydrogen, oxygen, carbon, silicon, helium, etc. I believe Mecrucry Is hugely iron in compesistion. You can refrence http://en.wikipedia.org/wiki/Planets to seek out more in depth on what each planet is made of.

Detritus from the big bang

Mercury - Has a dense iron core that comprises the majority of the planet with a silicate mantle and crust. (Subject to debate: very little iron has been found on Mercury's surface, meaning there would have to be a great deal of differentiation between the core and the rest of the planet) Venus - Probably has a mostly nickel and iron interior, though this is unproven because of difficulties in collecting data from the planet. This is assumption is based on Venus' similarities to Earth. Its atmosphere is made almost entirely (around 95%) of Carbon Dioxide. Earth - Composed mostly of iron (roughly 30%, largely concentrated in the core), oxygen (around 30%) and magnesium (around 14%). Mars - Like the rest of the inner planets, made mostly of iron, with around 16% sulfur in the core and a silicate mantle. Jupiter - 90% Hydrogen and 10% Helium (75%/25% by weight). It is speculated to have a rocky core, but the pressures that far into the planet prevent testing at this point in time. The main bulk of the planet probably consists of liquid metallic hydrogen Saturn - Roughly similar percentages to Jupiter, but its interior is hot and gives off more radiation than it receives from the Sun. Why is still open to speculation. Uranus - atmosphere is 83% hydrogen, but this is only 15% of the planet's total make up. Primarily, it is made of rock and ice (ice usually being a mixture of water, methane and ammonia). Neptune - Also made up mostly of rock and ice, with only around 15% hydrogen. Very little is known about Pluto's over all composition -- and it's technically no longer a planet. See http://www.nineplanets.org/ for a good resource.

Parian Marble (the Venus de Milo, that is...)

Venus is made up of hard rock, like earth, and the core of the planet Venus is made of nickel-iron. At this website, you can find more information on Venus. http://en.wikibooks.org/wiki/Wikijunior_Solar_System/Venus#What_is_the_surface_like_on_this_planet.3F I hope this helps you!!

Some planets are made of rock and metal (like Earth), some are made of liquid and gas (like Jupiter), but Pluto is the only planet made of ice and rock.

Atoms of known and perhaps unknown elements.

Mercury, Venus, Earth and Mars are rocky planets. Im not sure of the composition of the rocks on the first 4 rocky planets but I know that Earth is geologically active so is made up of countless rocks and minerals, mars is made up mainly of an iron oxide based rock. Going back to Mercury, Mercury has a large iron core (electromagnetic waves from the iron core should protect Mercurys atmosphere) but Mercury lost its atmosphere due to being so close to the sun. Venus probably has an iron core like earth. The earths iron core emits a very large electro magnetic shield around the planet which deflects the harmful solar wind from the sun. Sadly, Mars doesnt have an iron core, but a rocky one, so Mars doesnt have this electro magnetic protection. This means that Mars has had its atmosphere stripped away over millions of years by the suns solar winds. Jupiter and Saturn are gas giants with atmospheres of similar compositon to each other. Jupiter consists of 90% hydrogen and 10% helium. Neptune and Uranius the outer gas giants) are probably around half the size of Jupiter but their atmospheres may consist mainly of helium (Im not sure?) pluto is a very small rocky planet and these days, scientists regard pluto as being too small to be called a planet so now scientists or some astronomers regard Uranus as the last planet in our solar system. Hope this helps!

Mercury, Venus, Earth, Mars are made of rock and metal. Jupiter, Saturn, Neptune, and Uranus are made of helium, hydrogen, and water - called the gas giants. Pluto the dwarf planet is made of rocks and metals too. Joy =)

Earth and the other three inner planets of our solar system (Mercury, Venus and Mars) are made of rock, containing common minerals like feldspars and metals like magnesium and aluminum. So is Pluto. The other planets are not solid. Jupiter, for instance, is made up mostly of trapped helium, hydrogen, and water. In our solar system, the four "gas giants" are Jupiter, Saturn, Neptune, and Uranus.

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yoyyoyoyoyoyoyoyoyoy i like earth