Mercury

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Mercury is the closest planet to the sun. It is also the smallest. Mercury takes 88 Earth days to revolve around the sun. Mercury formed about 4.5 billion years ago. No people have ever gone to Mercury, but the first robotic spacecraft to go to there was called Mariner 10. Mercury is named after the Roman messenger god because it is the fastest moving planet in the solar system. Mercury is sometimes called the "Morning star" because it can be seen in the late evening and early morning. Mercury's core makes up 75% of the planet. Its orbit is 57,910,000 km from the sun. Its diameter is 4,880 km. It is similar to the moon because it is old, heavily cratered, and has no plate tectonics. Mercury has no moons. Mercury is a greyish color that highly resembles the moon. Mercury is not the hottest planet in the sun, Venus is. Mercury's diameter is 40% larger than the moon's and 40% smaller than Earth's. It is smaller than Jupiter's moon Ganymede and Saturn's moon Titan.

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**Works Cited** **Sources** : Include the source information for all of the magazine articles, reference sources (encyclopedias) and web site pages that were used to complete your project. The source information for encyclopedias may be found at the end or beginning of each entry in iCONN. When using periodicals, the publication information will be at the beginning or end of the article. This needs to be formatted for MLA standards. If it is not labeled 'Source Citation' it can be formatted appropriately by using EasyBib.com. You should use EasyBib for the web sites. The final Works Cited should be listed in alphabetical order by the first word of the source citation. "Milky Way." //Kids InfoBits Presents: Astronomy//. Gale, 2008. Reproduced in Kids InfoBits. Detroit: Gale, 2012. "The Milky Way." //WMAP's Universe//. NASA, 28 June 2010. Web. 06 Mar. 2012. . Vergano, Dan. "Galaxy Bracketed by Big Bubbles." //USA Today// 10 Nov. 2010: 05A. Web. 6 Mar. 2012.
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**Topic: Research Focus**
 * What is your topic? Mercury**
 * State the focus of your research: Physical facts about mercury**

**Notes** Include notes, statistics and facts that you will use to write your final paper. You may want to label sections of your notes to help you be more organized as you write. As you take notes from a source, you should list the source citation in the Works Cited section above. > > Mercury is the smallest and fastest planet in the solar system. It is also the closest planet to the sun. It is named after the Roman messenger god Mercury, the fastest Roman god. The planet Mercury was known by ancient people thousands of years ago. It has no moons. What Is the Planet Mercury?03.30.11 > > This picture of Mercury was taken by NASA's MESSENGER spacecraft. Image Credit: NASA > > > Mercury is the smallest and fastest planet in the solar system. It is also the closest planet to the sun. It is named after the Roman messenger god Mercury, the fastest Roman god. The planet Mercury was known by ancient people thousands of years ago. It has no moons. > > > How Big Is Mercury? > > Mercury is the smallest of the eight planets in our solar system. It is only a little bigger than Earth's moon. It would take more than 18 Mercurys to be as big as Earth. If you could weigh Mercury and the moon, Mercury would weigh much more. Mercury has a rocky surface, but deep inside is a heavier material, probably iron. > > > Where Is Mercury? > > Mercury is the closest planet to the sun. On average, it is a little more than one-third the distance from the sun than Earth is. Mercury orbits the sun once every 88 Earth days. So one year on Mercury is 88 Earth days. A day on Mercury lasts even longer than a Mercury year. One Mercury day lasts for 176 Earth days. > > > MESSENGER has given scientists a better look at Mercury than they've ever had. Image Credit: NASA > What Is Mercury Like? > > The surface of Mercury looks much like Earth's moon. It has a lot of impact craters. Mercury has almost no atmosphere. Because it is so close to the sun, it can be very hot. On its sunny side, Mercury can reach a scorching 800 degrees Fahrenheit! (But Mercury is not the hottest planet in the solar system. The hottest planet is Venus.) On its dark side, Mercury gets very cold because it has almost no atmosphere to hold in heat and keep the surface warm. The temperature can drop down to minus 300 degrees Fahrenheit. Sunlight never reaches into the bottoms of some craters near Mercury’s poles. That could mean that ice may be inside those craters, because they always stay cold. > > > How Has NASA Studied Mercury? > > Because it is so close to the sun, Mercury is hard to study from Earth. No people have ever gone to Mercury, but the first robotic spacecraft to visit Mercury was Mariner 10. It flew by Mercury in 1974 and 1975. Mariner 10 was able to take pictures of less than half of Mercury's surface. No spacecraft visited Mercury for more than 30 years. Then NASA's MESSENGER flew by Mercury in 2008 and 2009. On March 17, 2011, it began its orbit of Mercury. MESSENGER will map Mercury by taking pictures of the planet’s surface, including some areas that have not been seen before. It will also collect data on the composition of the surface rocks, and measure the heights of mountains and depths of craters and valleys. Some data collected by MESSENGER will help scientists to understand what the inside of Mercury is like. MESSENGER will let people learn more about Mercury than they ever have before. > **How Big Is Mercury?** Mercury is the smallest of the eight planets in our solar system. It is only a little bigger than Earth's moon. It would take more than 18 to be as big as Earth. If you could weigh Mercury and the moon, Mercury would weigh much more. Mercury has a rocky surface, but deep inside is a heavier material, probably iron. **Where Is Mercury?** Mercury is the closest planet to the sun. On average, it is a little more than one-third the distance from the sun than Earth is. Mercury orbits the sun once every 88 Earth days. So one year on Mercury is 88 Earth days. A day on Mercury lasts even longer than a Mercury year. One Mercury day lasts for 176 Earth days. > ** What Is Mercury Like? ** The surface of Mercury looks much like Earth's moon. It has a lot of impact craters. Mercury has almost no atmosphere. Because it is so close to the sun, it can be very hot. On its sunny side, Mercury can reach a scorching 800 degrees Fahrenheit! (But Mercury is not the hottest planet in the solar system. The hottest planet is Venus.) On its dark side, Mercury gets very cold because it has almost no atmosphere to hold in heat and keep the surface warm. The temperature can drop down to minus 300 degrees Fahrenheit. Sunlight never reaches into the bottoms of some craters near Mercury’s poles. That could mean that ice may be inside those craters, because they always stay cold. **How Has NASA Studied Mercury?** Because it is so close to the sun, Mercury is hard to study from Earth. No people have ever gone to Mercury, but the first robotic spacecraft to visit Mercury was Mariner 10. It flew by Mercury in 1974 and 1975. Mariner 10 was able to take pictures of less than half of Mercury's surface. No spacecraft visited Mercury for more than 30 years. Then NASA's MESSENGER flew by Mercury in 2008 and 2009. On March 17, 2011, it began its orbit of Mercury. MESSENGER will map Mercury by taking pictures of the planet’s surface, including some areas that have not been seen before. It will also collect data on the composition of the surface rocks, and measure the heights of mountains and depths of craters and valleys. Some data collected by MESSENGER will help scientists to understand what the inside of Mercury is like. MESSENGER will let people learn more about Mercury than they ever have oman messenger god Mercury, the fastest Roman god. The planet Mercury was known by ancient people thousands of years ago. It has no moons. **How Big Is Mercury?** Mercury is the smallest of the eight planets in our solar system. It is only a little bigger than Earth's moon. It would take more than be as big as Earth. If you could weigh Mercury and the moon, Mercury would weigh much more. Mercury has a rocky surface, but deep inside is a heavier material, probably iron. **Where Is Mercury?** Mercury is the closest planet to the sun. On average, it is a little more than one-third the distance from the sun than Earth is. Mercury orbits the sun once every 88 Earth days. So one year on Mercury is 88 Earth days. A day on Mercury lasts even longer than a Mercury year. One Mercury day lasts for 176 Earth days. > ** What Is Mercury Like? ** The surface of Mercury looks much like Earth's moon. It has a lot of impact craters. Mercury has almost no atmosphere. Because it is so close to the sun, it can be very hot. On its sunny side, Mercury can reach a scorching 800 degrees Fahrenheit! (But Mercury is not the hottest planet in the solar system. The hottest planet is Venus.) On its dark side, Mercury gets very cold because it has almost no atmosphere to hold in heat and keep the surface warm. The temperature can drop down to minus 300 degrees Fahrenheit. Sunlight never reaches into the bottoms of some craters near Mercury’s poles. That could mean that ice may be inside those craters, because they always stay cold. **How Has NASA Studied Mercury?** Because it is so close to the sun, Mercury is hard to study from Earth. No people have ever gone to Mercury, but the first robotic spacecraft to visit Mercury was Mariner 10. It flew by Mercury in 1974 and 1975. Mariner 10 was able to take pictures of less than half of Mercury's surface. No spacecraft visited Mercury for more than 30 years. Then NASA's MESSENGER flew by Mercury in 2008 and 2009. On March 17, 2011, it began its orbit of Mercury. MESSENGER will map Mercury by taking pictures of the planet’s surface, including some areas that have not been seen before. It will also collect data on the composition of the surface rocks, and measure the heights of mountains and depths of craters and valleys. Some data collected by MESSENGER will help scientists to understand what the inside of Mercury is like. MESSENGER will let people learn more about Mercury than they ever have before.
 * Mercury is the closest planet to the sun
 * It is the smallest planet
 * Its orbit is 57,910,000 km from the sun
 * Its diameter is 4,880 km
 * Mercury has been visited by two spacecraft, mariner 10 and MESSENGER
 * It is similar to the moon because its surface is heavily cratered, it is very old, and it has no plate tectonics

Mercury is the closest planet to the [|Sun] and the eighth largest. Mercury is slightly smaller in diameter than the moons [|Ganymede] and [|Titan] but more than twice as massive. [|orbit]: 57,910,000 km (0.38 [|AU]) from Sun [|diameter]: 4,880 km [|mass]: 3.30e23 k

In Roman mythology [|Mercury] is the god of commerce, travel and thievery, the Roman counterpart of the Greek god [|Hermes], the messenger of the Gods. The planet probably received this name because it moves so quickly across the sky. Mercury has been known since at least the time of the Sumerians (3rd millennium BC). It was sometimes given separate names for its apparitions as a morning star and as an evening star. Greek astronomers knew, however, that the two names referred to the same body. Heraclitus even believed that Mercury and Venus orbit the Sun, not the Earth. Since it is closer to the Sun than the Earth, the illumination of Mercury's disk varies when viewed with a telescope from our perspective. [|Galileo]'s telescope was too small to see Mercury's phases but he did see the phases of [|Venus]. Mercury has been now been visited by two spacecraft, [|Mariner 10] and [|MESSENGER]. Marriner 10 flew by three times in 1974 and 1975. Only 45% of the surface was mapped (and, unfortunately, it is too close to the Sun to be safely imaged by [|HST]). [|MESSENGER] was launched by NASA in 2004 and will orbit Mercury starting in 2011 after several flybys. Its first flyby in Jan 2008 provided new high quality [|images]of some of the terrain not seen by Marriner 10. Mercury's orbit is highly **eccentric**; at [|perihelion] it is only 46 million km from the Sun but at [|aphelion] it is 70 million. The position of the perihelion precesses around the Sun at a very slow rate. 19th century astronomers made very careful observations of Mercury's orbital parameters but could not adequately explain them using [|Newtonian] mechanics. The tiny differences between the observed and predicted values were a minor but nagging problem for many decades. It was thought that another planet (sometimes called [|Vulcan]) slightly closer to the Sun than Mercury might account for the discrepancy. But despite much effort, no such planet was found. The real answer turned out to be much more dramatic: [|Einstein]'s [|General Theory of Relativity]! Its correct prediction of the motions of Mercury was an important factor in the early acceptance of the theory. Until 1962 it was thought that Mercury's "day" was the same length as its "year" so as to keep that same face to the Sun much as the [|Moon] does to the [|Earth]. But this was shown to be false in 1965 by doppler radar observations. It is now known that Mercury rotates three times in two of its years. Mercury is the only body in the solar system known to have an orbital/rotational [|resonance]with a ratio other than 1:1 (though many have no resonances at all). This fact and the high eccentricity of Mercury's orbit would produce very strange effects for an observer on Mercury's surface. At some longitudes the observer would see the Sun rise and then gradually increase in apparent size as it slowly moved toward the zenith. At that point the Sun would stop, briefly reverse course, and stop again before resuming its path toward the horizon and decreasing in apparent size. All the while the stars would be moving three times faster across the sky. Observers at other points on Mercury's surface would see different but equally bizarre motions. Temperature variations on Mercury are the most extreme in the solar system ranging from 90 K to 700 K. The temperature on [|Venus] is slightly hotter but very stable. Read more about [|Mercury l Mercury facts, pictures and information.] by [|nineplanets.org] Mercury was named by the Romans after the fleet-footed messenger of the gods because it seemed to move more quickly than any other planet. It is the closest planet to the [|Sun], and second smallest planet in the [|solar system]. Its diameter is 40% smaller than [|Earth] and 40% larger than the [|Moon]. It is even smaller than [|Jupiter's] moon [|Ganymede] and [|Saturn's] moon [|Titan]. If an explorer were to step onto the surface of Mercury, he would discover a world resembling lunar terrain. Mercury's rolling, dust-covered hills have been eroded from the constant bombardment of [|meteorites]. Fault-cliffs rise for several kilometers in height and extend for hundreds of kilometers. Craters dot the surface. The explorer would notice that the Sun appears two and a half times larger than on Earth; however, the sky is always black because Mercury has virtually no atmosphere to cause scattering of light. As the explorer gazes out into space, he might see two bright stars. One appearing as cream colored [|Venus] and the other as blue colored [|Earth]. Until [|Mariner 10], little was known about Mercury because of the difficulty in observing it from Earth telescopes. At maximum elongation it is only 28 degrees from the Sun as seen from Earth. Because of this, it can only be viewed during daylight hours or just prior to sunrise or after sunset. When observed at dawn or dusk, Mercury is so low on the horizon that the light must pass through 10 times the amount of Earth's atmosphere than it would if Mercury was directly overhead. During the 1880's, Giovanni Schiaparelli drew a sketch showing faint features on Mercury. He determined that Mercury must be tidally locked to the Sun, just as the Moon is tidally locked to Earth. In 1962, radio astronomers looked at radio emissions from Mercury and determined that the dark side was too warm to be tidally locked. It was expected to be much colder if it always faced away from the Sun. In 1965, Pettengill and Dyce determined Mercury's period of rotation to be 59 +- 5 days based upon radar observations. Later in 1971, Goldstein refined the rotation period to be 58.65 +- 0.25 days using radar observations. After close observation by the Mariner 10 spacecraft, the period was determined to be 58.646 +- 0.005 days. Although Mercury is not tidally locked to the Sun, its rotational period is tidally coupled to its orbital period. Mercury rotates one and a half times during each orbit. Because of this 3:2 resonance, a day on Mercury (sun rise to sun rise) is 176 Earth days long as shown by the following diagram. The pictures returned from the Mariner 10 spacecraft showed a world that resembles the moon. It is pocked with craters, contains hugh multi-ring basins, and many lava flows. The craters range in size from 100 meters (the smallest resolvable feature on Mariner 10 images) to 1,300 kilometers. They are in various stages of preservation. Some are young with sharp rims and bright rays extending from them. Others are highly degraded, with rims that have been smoothed from the bombardment of meteorites. The largest crater on Mercury is the [|Caloris basin]. A basin was defined by Hartmann and Kuiper (1962) as a "large circular depression with distinctive concentric rings and radial lineaments." Others consider any crater larger than 200 kilometers a basin. The Caloris basin is 1,300 kilometers in diameter, and was probably caused by a projectile larger than 100 kilometers in size. The impact produced concentric mountain rings three kilometers high and sent ejecta 600 to 800 kilometers across the planet. (Another good example of a basin showing concentric rings is the [|Valhalla region] on [|Jupiter's] moon [|Callisto].) The seismic waves produced from the Caloris impact focused onto the other side of the planet and produced a region of chaotic terrain. After the impact the crater was partially filled with lava flows. Mercury is marked with great curved cliffs or lobate scarps that were apparently formed as Mercury cooled and shrank a few kilometers in size. This shrinking produced a wrinkled crust with scarps kilometers high and hundreds of kilometers long. The majority of Mercury's surface is covered by plains. Much of it is old and heavily cratered, but some of the plains are less heavily cratered. Scientists have classified these plains as intercrater plains and smooth plains. Intercrater plains are less saturated with craters and the craters are less than 15 kilometers in diameter. These plains were probably formed as lava flows buried the older terrain. The smooth plains are younger still with fewer craters. Smooth plains can be found around the Caloris basin. In some areas patches of smooth lava can be seen filling craters. Mercury's history of formation is similar to that of Earth's. About 4.5 billion years ago the planets formed. This was a time of intense bombardment for the planets as they scooped up matter and debris left around from the nebula that formed them. Early during this formation, Mercury probably differentiated into a dense metallic core, and a silicate crust. After the intense bombardment period, lava flowed across the surface and covered the older crust. By this time much of the debris had been swept up and Mercury entered a lighter bombardment period. During this period the intercrater plains formed. Then Mercury cooled. Its core contracted which in turn broke the crust and produced the prominent lobate scarps. During the third stage, lava flooded the lowlands and produced the smooth plains. During the fourth stage micrometeorite bombardment created a dusty surface also known as regolith. A few larger meteorites impacted the surface and left bright rayed craters. Other than the occasional collisions of a meteorites, Mercury's surface is no longer active and remains the same as it has for millions of years. How much would you weigh on Mercury? If you moved to Mercury you would not weigh as much as you do on Earth. Not because you would lose weight on the spaceship, but because Mercury is smaller, and so has less gravity. If you weigh 70 pounds (32 kg) on Earth, you would weigh only about 27 pounds (12 kg) on Mercury.

The Planet The planet Mercury is the closest of the planets to the Sun. Because this planet lies so close to the Sun, and as a result somewhat near to Earth, it is visible to observers on Earth in the late evening or early morning sky. Because of this, Mercury has become a part of the mythology and legend of almost every culture throughout the history of the Earth. This planet is often called a morning star. This is because Mercury shines brightly in the early morning just before the sun rises. It has also been called an evening star for the same reason. Mercury is often visible for a brief period of time just after the Sun sets. Mercury is Heavy Because of its proximity to the Sun, Mercury's evolution took a slightly different course than that of the other planets. As the Sun formed, it pushed much of the lighter gas and dust out of the inner Solar System, leaving behind only heavier elements. As a result, Mercury is made out of a large percentage of heavier elements, mainly iron. It is essentially a large metal ball of iron with a very thin silicate crust. Mercury's core makes up about 75% of the planet. Its thin mantle, or crust, is only about 300 to 400 miles thick (500 to 600 km). Next to Earth, Mercury is the second most dense planet in our Solar System. Mercury Has Wrinkles As Mercury's iron core cooled it contracted, or shrunk. This caused its rocky crust to become wrinkled. Scientists call these wrinkles Lobate Scarps. This scarps can be hundreds of miles long and even up to a mile high. Mercury's core has not cooled completely, however. Researcher recently found evidence that Mercury has a molten core. Mercury is Scarred