Planets | Scholastic Grades 3–5, 6–8, 9–12 The following questions were answered by astronomer Dr. Cathy Imhoff of the Space Telescope Science Institute. Do all the planets have seasons? What causes seasons? Earth is tilted with respect to its orbit around the sun. So when our North Pole is tilted toward the sun, we get summer in the Northern Hemisphere (winter in the south). When the South Pole is tilted toward the sun, we get winter. So if a planet is tilted with respect to its orbit around the sun, it should have seasons. Here are the numbers that I was able to find this morning (as of September 1994) Venus — 23 degrees tilt, Earth — 23.5, Mars — 24, Jupiter — 3, Saturn — 27, Uranus — 98, Neptune — 29. But you can see that most of the planets have tilts like Earth, so they must have seasons. As I noted above, we definitely see seasons on Mars. In winter its ice caps grow, in summer they shrink. Jupiter has very little tilt, so it doesn't experience noticeable seasons.

But Neptune is turned all the way over on its side! It must have very strange seasons! How did the planets get their names? Five of the planets were known to people thousands of years ago. They are bright enough to be seen with the naked eye and they move with respect to the stars. The name planet comes from the Greek word for "wanderer." I'm sure that people in different lands had various names for them, but the names we use come from the ancient Greeks and Romans. They named the planets for some of their gods. Mercury was the Roman god of commerce and cunning, and also messenger to the gods. Venus was the goddess of love. Mars was the god of war. Jupiter was the chief god. Saturn was the god of agriculture. When the next planet was found by Sir William Herschel in 1781, there was quite a debate about what to name it. Finally everyone decided to stay with the Roman names from mythology. So the new planet was finally named Uranus, for the father of the Titans. The next planet was named Neptune, for the god of the seas. And Pluto was named for the god of the underworld.

Most of the moons and some asteroids are also named from Roman mythology. What was the first planet discovered? Who discovered it? What kind of equipment did they use? 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. Herschel was one of the first modern astronomers. His patron was King George III of England (the same King George from the time of the American Revolution!). Herschel wanted to name the planet after King George, but nobody else liked that so they gave it the name Uranus. Herschel and his sister Charlotte (who was an astronomer in her own right) used several reflecting telescopes, some of the first based on a design invented by Sir Isaac Newton. The largest was over 40 feet long and had a mirror 48 inches across. It was held up with a framework of wood, and they had to have helpers move it around using ropes and pulleys. It was the largest telescope in the world until over 100 years later. Which planet was formed first and how was it formed?

We think that the planets all formed pretty much at the same time. However the sun probably formed first. The leftover gas and dust remained in a disk around the sun. In this disk, stuff began to clump and form "planetesimals" (pronounced pla-ne-TE-si-mals). These are small rocky bodies, something like asteroids. They crashed into each other and eventually formed the inner planets. At the same time, planetesimals formed the cores of the outer planets Jupiter and Saturn. Because of their strong gravity, they swept up a lot of gas. Uranus and Neptune did this too, but there was less gas around because Jupiter and Saturn got it first. The asteroid belt may be left-over planetesimals that never formed a planet because Jupiter's strong gravity nearby kept it from forming. Are there any living things on any of the planets? So far we know of only one planet with life — Earth! In 1976, we landed probes on Mars that looked carefully for evidence of life. But they couldn't find any. The other planets are less likely to have life (at least life like that on Earth) because they are too cold, too hot, don't have water or air.

So as far as we know, Earth is alone in this solar system in having life. Why are all planets round? Planets and stars are round because of gravity. Gravity pulls equally in all directions. Suppose you had a great big, tall mountain. As time goes by, rocks and dirt loosen up and fall down the mountain side. Eventually the mountain is worn down. Similarly a deep, deep valley will fill up. Of course a planet is not perfectly round — look at the mountains and valleys on the Earth and on Mars! Also the bigger the planet, the stronger the gravity. So bigger planets will be rounder. Tiny planets may not be very round. For instance, some of the moons around Jupiter are not very big and are not round — sort of oblong and irregular. Asteroids, which may be only a few miles long, are also irregular. Why does every planet have gravity? Every planet has gravity, because EVERYTHING has gravity! Even you do! All matter in the universe has gravity. The bigger something is, the more gravity it has. The earth has strong gravity, but the sun is much bigger and has much stronger gravity.

You also have gravity much, much, much smaller than the earth, so your gravity is very small. That's good or else things would be sticking to you! Why do some planets have more gravity than others? The strength of gravity depends on two things, the mass of the planet and how far we are from the center of the planet. So the gravity we would experience standing on the surface of a planet depends on how massive the planet is (the heavier the planet, the more gravity) and how big the planet is (the bigger the planet, the further we are standing from the center, and thus the gravity is less). Most of the planets in our solar system are more massive than Earth, but they are also larger, so you have to do the calculations to figure out how the surface gravity compares. How did the planets get the energy to rotate? Actually in space it is hard to get something to NOT rotate! The planets were formed from the same big cloud of gas and dust that formed the sun. That cloud, as it collapsed and started to form the sun, spun faster and faster as it got smaller. That is the way spin works — something that scientists call "conservation of angular momentum." A familiar example is an ice skater.

The ice skater starts to spin, and when she pulls her arms close around her the spin goes faster. You can do the same thing on a chair that lets you spin. Push yourself into a spin with your arms and legs stuck out. Then pull your arms and legs in to your body. Your chair will spin faster! Well the same thing happened to the cloud that formed the sun (which is spinning) and to the portions of the cloud that formed the planets. As their smaller clouds collapsed, they spun faster and faster. Could planets come together to form one large planet? When our solar system was forming, many small "planets" did collide to make bigger planets. But this stopped and as a result we have our current collection of planets. Their orbits are all very stable and they can't collide now. What are the relative distances of each of the planets from the sun? How long does it take for each of the planets to orbit the sun? Also, please provide any other data regarding the weight and such. Let's see if I can put the information into a table to help you to better understand: 0.06 NOTES: MASS, RADIUS, and SURFACE GRAVITY are all compared to Earth.

Earth's radius is about 3,800 miles. If you could weigh Earth, it would weigh13,000,000,000,000,000,000..... (24 zeros) pounds! Whoa! That's heavy! Do the weights of planets stay the same? Pretty much. Over millions of years, they pick up some space dust but that's very little compared to how much they weigh to start with. Can you tell if a comet crash is going to hit a planet before it happens? If we know about the comet and observe it, we can compute its orbit. Some astronomers specialize in big computer programs that can predict the orbits of the planets, comets, etc. So they can predict such a comet crash. That is what they did when Comet Shoemaker-Levy 9 was discovered — they showed that it was going to hit Jupiter. Small asteroids are harder, because they aren't as bright as comets. They are just "rocks," not glowing gases like the comets.

About once every 10 years we hear about some small asteroid that whizzed by the Earth and no one knew about it until just before or after it whizzed by. But the chance of one actually hitting Earth is still very very small. Thank goodness! Why are there nine planets? Instead of eight or ten? As far as I know, there is no special reason. Do the planets ever get smaller by melting and erosion? Melting and erosion must occur on other planets. For instance, Mars has ice caps, and the surface shows channels where water or something once flowed. Also we see dust storms. But do planets get smaller? I don't think so. Think about Earth — ice may melt and rocks erode, but that just moves stuff (water, sand) around on the surface. To make the planet get smaller, stuff would actually have to leave the planet! Gravity makes sure that it doesn't. Is there pollution on any of the planets? By pollution, we usually mean something man-made that doesn't belong there. I guess you could say that we have polluted the moon, Mars, and Venus, because we sent satellites and probes to them and just left them there when we were done with them!

Hopefully when the astronauts visited the moon, they cleaned up their Coke cans and orange peels before they flew back to Earth. Have scientists found any microscopic organisms that live on any (other) planet? The only place we have looked thoroughly is Mars, and nothing was found. Some people think that if we check closer to the ice caps, where there is more water, there might be a better chance. Hopefully some day we will do that. Do you have any new information on the new planets? Actually, there are now several stars that we know are planets. The first to be discovered was 51 Pegasi, but there are now five more stars similar to our sun that have at least one planet. The biggest planets are the easiest to find, so it's not surprising that all the planets found so far are around the size of Jupiter, our biggest planet. If you would like to read more details about these new planets around other stars, you can try the planet search Web page at ~gmarcy/planetsearch/planetsearch.html . Why do planets rotate on their axes? Well, it turns out that there is a lot of "spin" in the universe (a scientist would call it "angular momentum").

Everywhere you look planets, stars, and galaxies are spinning. It's hard to find something that isn't spinning! The planets are rotating because when they were formed, the cloud of gas and dust surrounding the young sun was circling it in orbit. Small icy, rocky "lumps" formed in this cloud and swept up smaller particles and gas. These clumps began to form planets. As the rocks, ice, and such fell onto these new planets they helped to keep them spinning. The planets closest to the sun, however, don't rotate as fast as they did when they were formed. The sun's gravity has slowed them down. Mercury and Venus both rotate rather slowly. Earth's gravity slowed the rotation of the moon, which is why now it always keeps one side to Earth. When do you think that humans will be starting to live on other planets? In your lifetime, we should be able to start small colonies on the moon and on Mars. It will be hard for them to be entirely self-sufficient though. It would be very hard to live on any of the other planets in our solar system. We might put small scientific stations on one of Jupiter's moons or in orbit around Jupiter or Saturn.

But good old Earth is the only place where life can prosper. Have there been any newly discovered planets? Recently there has been a planet discovered around a star named 51 Pegasi. This is a naked-eye star in the constellation Pegasus. We are particularly excited about this because the star is fairly similar to our sun. But the planet is nothing like the planets in our solar system. It is big — about half the size of Jupiter — but VERY close to the star. It must be very hot on that planet, and it must be made of rock and metal (not gases like Jupiter) in order to survive so close to the star. Some people have suggested that we name the planet Vulcan! Why do different planets have more moons? For planets, the bigger you are, the bigger your gravity is. If you have stronger gravity, then you can grab onto more moons. Jupiter and Saturn are the biggest planets, so they have the most moons. How many moons do each of the planets in our solar system have? Here are the moons that we know of. There may be more small moons around Jupiter, Saturn, Uranus, and Neptune that haven't been seen yet.

Mercury — 0 moons Pluto — 1 Do scientists think there might be a tenth planet in our solar system? For some time, astronomers have tried various ways to search for a tenth planet. But we now think that there are no new planets. One big reason is that the Infrared Astronomy Satellite, known as IRAS, did a very good map of the sky in infrared light. If any new planet were out there, IRAS should have found it. But it didn't. So we think that there are no more planets in our solar system. Are there any more planets in the galaxy? We think so. Our sun is a pretty typical star, and we are guessing that many stars have planets. So far we have found only a handful of planets around other stars. Planets are small and dim compared to their stars, and that makes them hard to find. Is there another planet like ours? The planet (which we know of) that is most similar to Earth is Mars. As you probably know, Mars is smaller, colder, and has less atmosphere. But it does seem to have some water (mostly ice) and on a really hot day can get to 80° Fahrenheit.

Have there ever been any other planets that dinosaurs could have survived on? I don't think so, at least for any of the planets in our solar system. Mars may have had some liquid water millions of years ago, and life might have started. But the atmosphere is too thin and too cold for life to have evolved very far. Venus is a horrible hothouse with acid rain. Mercury is terribly hot. Jupiter and the other planets are way too cold. Of course there could be another planet circling another star where life exists. But we don't know enough about those other planets yet to even say how many there are, much less whether dinosaurs (or people) could live there. But the universe is a very big place. I believe that there are living creatures out there somewhere! How do planets stay in orbit? The sun's gravity holds all the planets in orbit. Their orbits are a balance between gravity and the motion of the planet (if the planet wasn't moving, it would fall into the sun!). If the planets all lined up what would it be called? We would call it a planetary alignment.

When a planet lines up with the sun and Earth, and the planet is closer to the sun than Earth is, we call it a conjunction. If a planet lines up with the sun and Earth and the planet is farther from the sun than Earth, we call it opposition. There is also a cool word that isn't used very often except in crossword puzzles — syzygy (siz-i-gee) — which means any alignment of three bodies (sun, earth, moon, planet, whatever). How many words do you know that have three Y's in them? Will we ever be able to travel to another planet? Astronauts have walked on the moon. We have sent out spacecraft all over our solar system. So I think that within the next 20 or so years we will have people visit Mars. NASA has been working on how to do that for many years. But it is a big, difficult undertaking. Why doesn't gravity pull the planets into the sun? One approach is to go back to Sir Isaac Newton's reasoning — the famous apple falling from a tree event. This story may not be true but it is probably not far from how he came up with the ideas of gravity and motion.

Newton asked himself — why doesn't the moon fall to Earth, the way the apple falls from the tree? He reasoned that the motion of the moon around Earth had something to do with it. Suppose you threw the apple very hard. It would fall to earth, but not at the same spot. Suppose you could throw the apple so hard that it never fell to earth. It would keep circling Earth, just as the moon does. Similarly Earth's motion in its orbit keeps it from falling into the sun. On the other hand, the moon can't escape from Earth (or Earth from the sun) because of gravity. I haven't tried it but you could try magnets. Two magnets at rest will pull together, but if you slide one past the other fast enough they won't stick. It would probably be hard to get them to "orbit" each other! Have people found other solar systems with life on the planets? So far no, we have not found life anywhere but on Earth. We are also having a hard time finding planets around other stars. The problems are first, distances are so great. Second, the star is very much brighter than any planet would be. How do the gaseous planets get their gases?

Most of the "stuff" in the universe is gas. When our solar system formed, it was mostly gas with some dust. Earth was probably surrounded by gases. But Mercury, Venus, Earth, and Mars were all too close to the sun to hang onto most of their gases. The gases were heated or blown away. So those planets are rocky, with only thin gas atmospheres. The outer planets were far enough away from the sun that they held onto their gases. Even so they lost most of their lightest gases like hydrogen. How do gas planets stay together? How can gas have gravity? All matter, whether it is solid, liquid, or gas, has gravity. So the gas planets stay together because of the planets'gravity. How did planets get their rings? We think that small moons, or maybe comets, get too close to the planet. Then its gravity tears them apart. The bits of rock and ice then go into orbit around the planet and make rings. Some people think that Earth may have rings at one time! The ringed planets are next to each other. Is there a reason for that? A very good question!

I think that the planets that are closest to the sun, Mercury and Venus, don't have rings (or moons!) in part because the sun's gravity would pull them apart. Earth may have had rings in the past, but I think our moon's gravity would pull them apart. Mars might have had rings but the big planet Jupiter would probably pull them apart. The big outer planets — Jupiter, Saturn, Uranus, Neptune — all are big enough to have strong gravity to hold onto their rings. Also they are further from the sun and from each other. Pluto has a big moon, Charon, that would probably pull apart rings. What are the colors of all the planets? This is a really good question! Most of the planets don't have bright colors, so often the pictures have been "enhanced" or shown in "false colors" using computers to bring out the details. So in some of the pictures the colors you see are not be real. Here are the planets'colors as I understand them. Mercury is bare rock, a light gray color, like the moon. Venus'clouds are yellowish-white.

(There is a famous picture of Venus that looks dark blue and white — it is a "false color" picture that was actually taken in ultraviolet light to show the cloud patterns. I've also seen the same picture showing the clouds as light tan!) Earth is largely covered by water and there are lots of clouds, so it looks mostly blue and white. Mars really is red, a rusty orange-red color. Jupiter's clouds look yellowish white if you just look at it in the sky or through a telescope. True color pictures from Voyager show that some of the clouds look light brown and light orange. Many of the published pictures of Jupiter have been color enhanced to show the details in the clouds and the Red Spot (which is orangish-red). Saturn also looks yellowish-white. Its colors are similar to Jupiter's but not as strong. Uranus and Neptune look pale greenish-blue. Many of the pictures I have seen of them have the colors made stronger (bluer) than they really are. There aren't any detailed photos of Pluto yet, but it looks pretty much just white. This is reasonable since its surface is mostly ice.

If it were possible to put a colony of people on a planet with greater gravitational pull than Earth's, would there be a way to compensate for the greater force by using mechanical means? I wonder about the physical strain of living under 2 g (two times earth gravity) for example. We know that jet pilots who undergo high gravity experience certain physiological effects, including problems with blood pooling in their feet and away from their brains, and thus sometimes falling unconscious. They wear special pressure suits to help counteract that effect. These are sort of like elastic pants that help force the blood back up into the upper body. What planet is brightest in the skies in the morning? Venus is the bright object closest to the horizon in the east at dawn. It is brighter than any star, so it's pretty recognizable. Jupiter is also in the east, not quite as bright as Venus and further from the horizon. In late January early February Jupiter lies fairly close to a bright red star, Antares. Antares is the brightest star in the constellation. By the way, Saturn is low in the west in the evening sky. Mars is near opposition (i.e. opposite the sun) so it rises in the east around sunset.

It is noticeably red and lies near the sickle shape part of the constellation Leo. Are there planets around Vega? There is a disk of dusty material around Vega. I don't think anyone has found planets there. But planets are hard to find, so there might be planets that we can't see. × Life on other Planets and Moons in the Solar System - Universe Guide Home / Facts Life on other Planets and Moons in the Solar System At present the only planet or moon that is known to support life in the solar system is Earth. It is not to say that life can`t and doesn`t exist on other planets and moons, its just we`ve not finished checking everywhere yet. There are eight planets and an untold number of moons that have to be checked. Mercury Mercury, the closest planet to the Sun , is far too hot to support any life. It may have a thin atmosphere of oxygen but the heat from the Sun would vapourise and prevent any life forms from forming. It is safe to say that there is no life on the planet. There might be life forms deep under ground but that is highly unlikely.

Venus Venus was once thought to contain life especially as it was near our planet and within the goldilocks zone which Earth is also in. The goldilocks zone is the area of space that not too far and not too near the Sun for life to exist. Eagle comics in United Kingdom had a race of alien s known as the Treen in the Dan Dare stories that hid under the thick atmosphere. When space probes primarily from Russia or as it was known then, the Soviet Union sent Venera probes to the planet, they discovered that the planet was hot and a sulphuric atmosphere, one in which no life could exist because it was too toxic. However, on Earth, life has been known to exist in the most extreme of locations, near hot spurs under water but the atmosphere it too toxic at ground level. The pressure in the atmosphere would prevent anything from starting. There is a possibility that life forms, bacterial could life high in the atmosphere, at the very edge where the atmosphere is may just be right to support life. Niether Venus nor Mercury have any moons which could support life. Earth This, the third planet from the Sun, our home in the Solar System is the only planet that can at present support life naturally.

Earth has the right ingredients and is sufficiently far away from the Sun to be able to just the right temperature to support life. At present there are seven billion humans and an untold number of less intelligent animals and possibly trillions of other lifeforms including dogs, cats and micro-organism s. Micro-organisms include viruses and bacteria, however it depends on whether you class them as life. the moon has no atmosphere and therefore no life could ever exist on the planet. Whilst the moon was created by a planetoid smashing into the early Earth, life was not thought to have existed at the time of the smash and so no viral pollution would`ve ended up on the Moon. Mars There has always been speculation as to whether there is life on Mars or whether there had and no longer is life on Mars. The planet has featured as the home of a warrior race for hundred of years who wish to conquer the Earth such as in War of the Worlds by H.G. Wells. In Mars Attacks, the Martians lived underground whilst they plotted their conquest of our planet. We`ve been sending probes to the planet for tens of years but haven`t found any concrete evidence. The best evidence of life that scientists are hoping for is bacterial life forms.

As mentioned previously, bacteria on Earth have been found in the most extreme of locations. Even though the probes that are sent to outer space are sterialised to ensure that they don`t contain hitch-hiking bacteria, it is not 100% fail proof and Earth bacteria could in the most extremely rare case survive on the planet. The planet has ice caps on its north and south poles, bacterial could be encassed inside them. One theory is that life did take off on Mars but lost its ability to support life. On Earth, we have a magnetic field that protects us from the Sun`s radiation however on Mars, its shielding has disappeared and therefore advanced life would be killed off on the planet. There is a new race between the nations to get a community on Mars but we would need to build living quarters that would shield us from the Suns power, not an easy thing to do. Kim Stanley Robinson wrote about a trilogy of books (Red Mars, Green Mars, Blue Mars) about setting up on Mars and terraforming the planet. Terraforming the planet would be hinhibitively expensive and whether it could be done would need to be answered.

iMars is not in the goldilocks zone but one day, the Sun will start to expand and the goldilocks zone will move out further than it is and Mars will one day be in that zone. Humans wishing to survive will move to that planet before having to move again when the Sun expands further. Hopefully before we have to move from Earth or Mars, we will have created faster than light travel and have left the Solar System, having set up on an Extrasolar Planet. An extrasolar planet is a planet doesn`t orbit our Sun but orbits a star somewhere else in the galaxy . The two moons of Mars, Deimos and Phobos are thought to be two asteroid s that flew too close to Mars and were forced into orbit around the red planet. Asteroid Belt The asteroid belt contains hundreds and hundreds of rocky object, none of which could contain life. The rocks are belived to have been debris that couldn`t form into a rocky planet because of the influence of Jupiter, the largest planet in our solar system. The largest object is Ceres, now classified as a dwarf planet. Scientists now believe there is water vapour on the planetoid but not life. 1.

The chances of any life on any object within the asteroid belt is low, next to zero. Jupiter Jupiter is the largest planet in the solar system, some theorized it is a failed star that didn`t have enough energy or mass to become a star. It is thought to have a small rocky core but nothing able to support life. The atmosphere has high pressure and anything would be crushed to a pea by the strength of the gravity on the planet. The best chance of life existing here would be on a moon that is in orbit around the planet. Ganymede Ganymede is the biggest moon in the solar system, it is even bigger than the planet Mercury. Oxygen has been discovered in the atmosphere on the planet. It like Europa has an icy exteior but underneath the ice could be water if the planet core is hot enough to allow water to free flow. 2 Europa Europa is long seen as being a possibly moon that could support life forms. It has a icy crust which plumes of steam have been seen shooting out of its exterior. In 2001, a space odyssey, Europa is the planet where Earth is told to avoid but they could visit every other planet and moon in the solar system.

The planet is covered in a thick icy crust but under the crust, it is believed there could be free flowing water. it is one of the most likely candidates for life to exist on other than the Earth. Future N.A.S.A. science missions are being planned to visit the moon to study it. The first voyage to the planet would be to survey the planet from a satiellite with ice penetrators. Later missions would be to break the crust and send down a probe. Sending a probe into the ice crust does open possible ethical questions as we might be introducing a virus to their ecosystem which would klll the life forms off. An example of this is that when Europeans went to the Americas, they introduced unwittingly diseases which the natives had no natural resistence to. One of the things that life needs is heat and heat is generated on Europa by the gravity of Jupiter which causes the planet to expand and contract.3 Saturn Saturn is the second largest planet in the solar system, the first being Jupiter. Saturn is famous for its rings which all four gas giants have but the rings on Saturn are more prominent than the other planets. Like Jupiter, being a gas planet, it is unlikely to have a rocky core.

It doesn`t have a breathable atmosphere unlike Bespin, the gas giant in Star Wars. The rings are made up of rocks and ice and neither of those would be sufficient to support life. The most likey place to find life is on the atmospheric moon of Titan. Titan Although its name might create the impression it is the biggest, Ganymede is still bigger than Titan. The moon is the only moon in the solar system with an atmosphere. NASA/ESA/Italian Space Agency sent cassini-huygens spacecraft to the moon in the nineties to investigate the planet. The space probe was two parts, one was parachuted down to the planet. The project is still in progress but no reports of life has been reported yet. Cassini mission was not equiped with equipment to search for organic compounds so it is unlikely anything will be found as part of the mission. 4. According to ESA, there has been methane discovered in the atmosphere which is destroyed by sunlight but the quantities of methane that exists on the planet must indicate it is being regenerated by something else. Methane on Earth is a byproduct of organic life. 5 Enceladus Enceladus is the sixth largest moon orbiting Saturn.

Even though its the sixth largest, its not much bigger than the United Kingdom in size. It has a large ice shelf covering the planet and it is believed that somewhere under that ice could be an ocean. Where`s theres water, there`s possibility of life partly based on the fact that life came from basic life in the water. Uranus Uranus is a gas giant with like the other planets has a large number of moons. The planet itself would not be able to support life as there is no surface and it has a high pressure atmosphere. It would also been too far from the Sun. According to universe Today, life could possibly but unlikely exist on the planet. The planet has an atmosphere of Hydrogen and Helium but more importantly Methane. 6. Methane would have needed to have been produced somehow but probably not through the same way as it is on Earth. Uranus is also cold and well outside the Goldilocks Zone. Neptune At present due to the International Astronomical Union (IAU) downgrading the planet Pluto to dwarf planet, Neptune is currently the furthest planet from the Sun and the Earth for that matter as well.

Neptune is a large gas giant, blue in colour and with an untold number of moons. Whilst this site might detail 14 of its moons, they`ll be quite a few more, some undiscovered. Back to the planet at hand, the planet won`t have a solid sturface like that of Earth or Mars, it will most likely have a rocky core, not one on which life could exist on. The atmosphere would be heavy pressure and anthing if anything would need to have a strong body to withstand. The atmosphere contains methane which on Earth is a by-product of organic material so extremely possible something living could have created it. Like with all the other gas giants, if anything does live there, it would be microscopic organisms. 7 Pluto Up until the mid-noughties, Pluto was classified as a planet, it was downgraded after a vote by the I.A.U. What prompted the downgrading was the discovery of Eris, an object that was bigger than Pluto. Unlike the other outer planets, Pluto is a rocky planet like Mercury. Not much is known about Pluto as it is so far away. N.A.S.A. sent the New Horizons space probe out to study it for the first time.

It is so far from the Sun, the Sun is nothing more than a dot. Pluto is far too cold to allow for water to be free flowing on the planet. Unlike one of its moons Charon, it next to zero of finding life on the planet. Since we`ve been getting back data from Pluto, some scientists are beginning to think that there might be life on Pluto or under the surface. There won`t be intelligent or complex like us but microbial lifeforms like viruses. ref: Express Charon Charon is the biggest moon of the dwarf planet Pluto. According to NASA scientists, there is a remote chance that the moon could contain life under its icy crust. According to scientists analyzing the moon, they have said that cracks on the surface of the frozen moon say it points to the existence of strong, warm, tidal oceans beneath. As the discovery is new, the New Horizons craft would not have been kitted out with equipment to check for any possible life on the moon. 8 Eris The one time tenth planet provisionally called Xena after the Warrior Princess television character is so far away from Earth that we don`t know much about the dwarf planet. The only thing we do know is that its about the same size of the planet Pluto.

The only observations we have of the planet and its moon is from Earth based telescopes. At the moment, nothing is being sent out towards the planet. It is too far away from Pluto for the New Horizons to be redirected to it. The atmosphere at present is said to contain methane which could indicate a slight chance. The inner core of the planet could be heated from the core. 9. Sedna Sedna is one of the furthest objects in our solar system. Technically it is not part of the Solar System because it is so far from Pluto that it is intergalactic space. For any life to exist, the life would need to be not dependant on solar power and the planetoid must be able to generate its own heat source from within. Unless we get faster than light travel, there is no change of any space probe visiting the planet. Conclusion There is only one confirmed location at the moment that contains life presently and that is our home, planet Earth. Unless there is free flowing underwater activity on some of the moons in our solar system, the only life forms that we could possibly find elsewhere is bacterial. One day, we might get to Mars and discover that life once did exist but when the planet died, life died toon.

On Earth, high in the sky, talking cloud levels, micro-bacterial life has been discovered to exist which raises the possibility that life could exist on gas giants and Venus. The most likely place for life existing is on extrasolar planets. What Are the Two Planets That Don't Get Solar or Lunar Eclipses? | The Classroom | Synonym What Are the Two Planets That Don't Get Solar or Lunar Eclipses? by Chris Deziel The interplay of Earth and the moon causes eclipses on Earth. Related Articles The Ordinal Position of the Planets As Earth and the moon revolve around the sun, they periodically align with the sun in such a way that Earth moves into the moon's shadow and vice versa. Known as eclipses, these are spectacular events for observers on Earth. But they cannot occur on Mercury or Venus: Neither planet has a moon. Eclipses on the other planets in our solar system are possible but probably different than those on Earth. Mercury The first planet in the solar system, Mercury, is closer to the sun than Earth by more than half. From Mercury's surface, the sun appears three times as large as it does from Earth.

If Mercury had a moon, it would have to be large enough to cover that disk for observers on the planet's surface to experience a solar eclipse. Such a moon, unless it were very close to the planet, would probably have to be larger than Mercury itself. Thirteen times every century, Earth falls into Mercury's shadow as it transits the sun and creates a tiny partial solar eclipse. Venus Venus, unlike Mercury, is closer to the Earth than it is to the sun and more closely resembles Earth in size and composition. There are no eclipses on Venus, but if a moon similar to the Earth's was placed at a similar distance as our moon, there probably would be. These eclipses might not be as spectacular as they are on Earth, however, because Venus is covered with a thick atmosphere. Like Mercury, Venus periodically transits the face of the sun to create a tiny eclipse on Earth. These transits occur much less frequently than on Mercury, only twice every century. In the 21st century, these transits occurred on June 8, 2004, and June 6, 2012. Mars Mars is Earth's nearest neighbor that lies beyond Earth's orbit.

It is smaller than Earth, but has two moons, Phobos and Deimos. These moons are very small, so small that they both lack the mass necessary for gravity to form them into spheres. Phobos is very close to the Martian surface -- only 6000 kilometers (3728 miles) away -- and is often in the shadow of the planet. Deimos is a little less than one-tenth the distance from Earth to our moon. But Deimos is only 15 kilometers (9 miles) wide, so although it can easily disappear in the shadow of Mars, it can't produce an eclipse. Eclipses from Phobos are also only partial and because the moon moves so quickly, last no longer than 30 seconds. Other Planets The planets that lie beyond Mars are gas giants except for Pluto, which planetary scientists recently reclassified as a dwarf planet. All planets beyond Mars, including Pluto, have moons. Some of them, such as Jupiter's Ganymede, are larger than Earth's moon, and photos taken by NASA's Voyager and Cassini spacecraft reveal shadows of moons on the surfaces of Jupiter and Saturn. This indicates the occurrence of solar eclipses as these bodies transit the sun.

Shadows of these planets are so large that the moons are in total eclipse for extended periods, up to eight days at a time in the case of Callisto, one of Jupiter's moons. References The Solar System The Solar System Our Solar System is an amazing place. Not only is it home to eight planets, it also hold several dwarf planets, hundreds of moons, and thousands of stars and asteroids. The eight planets in our Solar System are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. These planets orbit the Sun. Here is a funny song to help you remember the planets The Sun The Sun is the center of our Solar System. It is because of the Sun that our solar system gets its name. Sol is the Roman name for Sun. The Sun is the largest object within the Solar System - it makes up more than 95% of all the matter! It is because of the Sun's large size that the rest of the objects within the Solar System orbit around it. The Sun is very, very hot. It is 10,000 degrees Fahrenheit on its surface. Mercury Mercury is the closest planet to the Sun, making it the first planet in the Solar System.

It is named after the Roman messenger god. In mythology, the god was known for being quick - Mercury is the fastest of all the planets to orbit the Sun, because it has the smallest route it has to take! Mercury can occasionally be seen from Earth Mercury is the second densest planet in the Solar System It is mainly made up of iron There is no atmosphere on Mercury Despite its fast trip around the Sun, Mercury's revolution is very slow - one day on Mercury equals about 59 days on Earth! Venus Venus is the second planet from the Sun. It is named after the Roman goddess of beauty and love. Venus is almost the same size as Earth, but other than size the two planets are very different! Fun Facts about Venus Venus appears to be the brightest planet in the sky due to the reflection of the Sun from its clouds, and its closeness to Earth Venus has an incredibly thick atmosphere. This makes it the hottest of the inner planets Venus rotates East to West Venus is covered in volcanoes Venus does not have any moons Earth Earth is the only known planet that has any life forms in the Solar System. It is the third planet from the Sun. It is the only planet that is not named after a god.

Most of the Earth is covered in water - 70%! Earth has a thin atmosphere, that protects us from dangerous gasses and heat in space Earth is the largest of the inner planets Air, water, and land make up the Earth Earth's axis is tilted at 23.5 degrees This a video showing the many different life forms that Earth has Mars Mars is the fourth planet from the Sun. Named for the Roman god of war, it is also known as the "Red Planet". It is the last of the inner planets. Temperatures on Mars are very similar to temperatures on Earth It is believed that Mars once had water on its surface Mars is called the red planet because its surface is covered in red dust The largest volcano in the Solar System is on Mars. It is called Olympus Mons Mars has two small moons Jupiter Jupiter is the first of the outer planets, and the fifth planet from the Sun. It is named for the king of the Roman gods. It is the largest of all of the planets. Fun Facts about Jupiter Jupiter is best known for its "Great Red Spot" - a mass of hurricanes that have been storming for hundreds of years.

The spot is larger in size than that of Earth Jupiter is made up of gasses - there is no solid surface on it Jupiter is so big; Earth could fit inside of it more than 1,000 times! Jupiter has over 50 moons. Four of these moons are as big as planets Jupiter has the most active volcanic activity in the Solar System Learn more about the Great Red Spot! Saturn Saturn is the sixth planet from the Sun. It is named for the Roman god of agriculture. It is most well known for its highly visible rings. Other Features of the Solar System There are many other exciting elements in the Solar System. Here are a few. Asteroids Asteroids are rocky bodies in the Solar System that are too small to be considered actual planets. In between Mars and Jupiter lies the Asteroid Belt, containing well over 90,000 asteroids. Comets Comets are ice and rock that grow tails the closer they get to the sun. The hotter they get, the longer this "tail" becomes. The sunlight makes comets glow, which causes them to be visible on Earth. Dwarf Planets Dwarf planets are bodies that orbit the sun that are not considered large enough to be actual planets.

The most famous dwarf planet is Pluto, which was considered an actual planet up until 2006. Satellites Satellites are machines put into the Solar System by scientists in order to find out more about the Solar System, and what is in it. These machines take pictures, perform experiments, take data, and much, much more. Without them, we wouldn't have the vast amount of information that we have today. Summary The Solar System is a fascinating place. Each of the eight planets have their own unique features, but are also similar in some ways - much like people! It is amazing to think that the Solar System has been around for more than 4.6 billions years. Each of the eight planets orbits the sun in the same direction, and in their own time. We have so much more we can learn about the Solar System, and so much we have learned already today. sit this page to learn more interesting facts about the Solar System! Want to get an idea of how far apart the planets are? Click here! Resources Our Solar System. Retrieved from Solar System. Retrieved from

Question: Two of the planets in our Solar system don't have moons: Venus - and which other ?
Answer: MERCURY