How Long Is A Year On The Other Planets? - Universe Today Universe Today How Long Is A Year On The Other Planets? Article Updated: 29 Jan , 2016 by Matt Williams Here on Earth, we to end to not give our measurements of time much thought. Unless we’re griping about Time Zones, enjoying the extra day of a Leap Year, or contemplating the rationality of Daylight Savings Time, we tend to take it all for granted. But when you consider the fact that increments like a year are entirely relative, dependent on a specific space and place, you begin to see how time really works. Here on Earth, we consider a year to be 365 days. Unless of course it’s a Leap Year, which takes place every four years (in which it is 366). But the actual definition of a year is the time it takes our planet to complete a single orbit around the Sun. So if you were to put yourself in another frame of reference – say, another planet – a year would work out to something else. Let’s see just how long a year is on the other planets, shall we?

A Year On Mercury: To put it simply, Mercury has an orbital period of 88 days (87.969 to be exact), which means a single year is 88 Earth days – or the equivalent of about 0.241 Earth years. But here’s the thing. Because of Mercury’s slow rotation (once every 58.646 days) and its rapid orbital speed (47.362 km/s), one day on Mercury actually works out to 175.96 Earth days. MESSENGER maps of Mercury – a monochrome map at 250 m/pixel and an eight-color (left), 1-km/pixel color map. Small gaps will be filled in during the next solar day (right). Credit: NASA/Johns Hopkins University APL/Carnegie Institution of Washington So basically, a single year on Mercury is half as long as a Mercurian (aka. Hermian) day. This is due to Mercury being the closest planet to the Sun, ranging from 46,001,200 km at perihelion to 69,816,900 km at aphelion.

At that distance, the planet shoots around the Sun faster than any other in our Solar System and has the shortest year. In the course of a year, Mercury experiences intense variations in surface temperature – ranging from 80 °K (-193.15 °C;-315.67 °F) to 700 °K (426.85 °C; 800.33 °F). However, this is due to the planet’s varying distance from the Sun and its spin, which subjects one side to extended periods of extremely hot temperatures and one side to extended periods of night. Mercury’s low axial tilt (0.034°) and its rapid orbital period means that there really is no seasonal variation on Mercury. Basically, one part of the year is as hellishly hot, or horribly cold, as any other. A Year On Venus: The second closest planet to our Sun, Venus completes a single orbit once ever 224.7 days. This means that a single year on Venus works out to about 0.6152 Earth years. But, once again, things are complicated by the fact that Venus has an unusual rotation period.

In fact, Venus takes 243 Earth days to rotate once on its axis – the slowest rotation of any planet – and its rotation is retrograde to its orbital path. The planet Venus, as imagined by the Magellan 10 mission. Credit: NASA/JPL Combined with its orbital period, this means that a single solar day on Venus (the time between one sunup to the next) is 117 Earth days. So basically, a single year on Venus is lasts 1.92 Venusian (aka. Cytherean) days. Again, this would make for some confusing time-cycles for any humans trying to make a go of it on Venus! Also, Venus has a very small axial tilt – 3° compared to Earth’s 23.5° – and its proximity to the Sun makes for a much shorter seasonal cycle – 55-58 days compared to Earth’s 90-93 days. Add to that its unusual day-night cycle, variations are very slight. In fact, the temperate on Venus is almost always a brutal 736 K (463 °C ; 865 degrees °F), which is hot enough to melt lead!

A Year On Earth: Comparatively speaking, a year on Earth is pretty predictable, which is probably one of the reasons why life is able to thrive here. In short, our planet takes 365.2564 solar days to complete a single orbit of the Sun, which is why we add an extra day to the calendar every four years (i.e. a Leap Year, which 2016 happens to be). But because our axis is tilted, there is considerable variation in the seasons during the course of a year. During the winter, when one hemisphere is pointed away from the Sun, the Sun’s distance from the equator changes by up to 23.5°. As a result, between the summer and winter, the length of days and nights, temperatures, and seasons will go through significant changes. Above the Arctic Circle, an extreme case is reached where there is no daylight at all for part of the year – up to six months at the North Pole itself, in what is known as a “polar night”. In the southern hemisphere the situation is exactly reversed, with the South Pole experiencing a midnight sun, a day of 24 hours, again reversing with the South Pole.

Every six months, the order of this is reversed. A Year On Mars: Mars has one of the highest eccentricities of any planet in the Solar System, ranging from 206,700,000 km at perihelion and 249,200,000 km at aphelion. This large variation and its greater distance from the Sun, leads to a rather long year. Basically, Mars takes the equivalent of 687 (Earth) days to complete a single orbit around the Sun, which works out to to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours. On the other hand, Mars has a rotation period that is very similar to Earth’s – 24 hours, 39 minutes, and 35.244 seconds. So while the days on Mars are only slightly longer, the seasons are generally twice as long. But this is mitigated by the fact that seasonal changes are far greater on Mars, owing to its eccentricity and greater axial tilt (25.19°).

During the winter, the global atmospheric pressure on Mars is 25% lower than during summer. This is due to temperature variations and the complex exchange of carbon dioxide between the Martian dry-ice polar caps and its CO2 atmosphere. As a result, Martian seasons vary greatly in duration than those on Earth, change roughly every six months, and do not start on the same Earth day every Martian year. Mars 2001 Global Dust Storm, as captured by the Hubble Space Telescope. Credit: NASA/J. Bell (Cornell)/M. Wolff (SSI)/Hubble Heritage Team (STScI/AURA) A Year On Jupiter: Jupiter is another interesting case. Whereas the gas giant only takes 9 hours 55 minutes and 30 seconds to rotate once on its axis, it also takes alson 11.8618 Earth years to complete an orbit around the Sun. This means that a year on Jupiter is not only the equivalent of 4,332.59 Earth days, but 10,475.8 Jovian days. That’s a lot of sunrises!

Much like Venus, Jupiter has an axial tilt of only 3 degrees, so there is literally no seasonal variation between the hemispheres. In addition, temperature variations are due to chemical compositions and depths rather than seasonal cycles. So while it does have “seasons”, which change very slowly due to its distance from the Sun – each season lasts 3 years – they are not similar to what terrestrial planets experience. A Year On Saturn: Much like its fellow gas giant Jupiter, Saturn takes it time completing a single orbit of the Sun, but rotates on its axis very rapidly. All told, a year on the planet lasts the equivalent of 10,759 Earth days (or about 29 1?2 years). But since it only takes 10 hours, and 33 minutes to complete a single rotation on its axis, a year on Saturn works out to 24,491.07 Saturnian (aka. Cronian) days. This portrait looking down on Saturn and its rings was created from images obtained by NASA’s Cassini spacecraft on Oct. 10, 2013. Credit: NASA/JPL-Caltech/Space Science Institute/G.

Ugarkovic Due to its axial tilt of almost 27 degrees (slightly more than Mars), Saturn experiences some rather long seasonal changes. But due to it being a gas giant, this does not result in variations in temperature. Combined with its distance from the Sun (at an average distance of 1,429.39 million km or 9.5 AU), a single season lasts more than seven years. A Year On Uranus: Uranus has some of the strangest annual and seasonal variations of any planet in the Solar System. For one, the gas/ice giant takes about 84 Earth years (or 30,688.5 Earth days) to rotate once around the Sun. But since the planet takes 17 hours, 14 minutes and 24 seconds to complete a single rotation on its axis, a year on Uranus lasts 42,718 Uranian days. However, this is confounded due to Uranus’ axial tilt, which is inclined at 97.77° towards the Sun. This results in seasonal changes that are quite extreme, and unique to Uranus. In short, when one hemisphere is pointed towards the Sun (i.e.

in summer), it will experience 42 years of continuous light. In winter, the situation is reversed, with this same hemisphere experiencing 42 years of continuous darkness. A Year On Neptune: Given its distance from the Sun, Neptune has the longest orbital period of any planet in the Solar System. As such, a year on Neptune is the longest of any planet, lasting the equivalent of 164.8 years (or 60,182 Earth days). But since Neptune also takes comparatively little time to rotate once on its axis (16 hours, 6 minutes and 36 seconds), a single year lasts a staggering 89,666 Neptunian days. Reconstruction of Voyager 2 images showing the Great Black spot (top left), Scooter (middle), and the Small Black Spot (lower right). Credit: NASA/JPL What’s more, with an axial tilt close to Earth and Mars’ (28.5 degrees), there is some seasonal variation on the planet. Essentially, a single season lasts more than 40 years. But like all gas/ice giants, this does not result in noticeable temperature variations.

How Long it Takes for Each Planet to Orbit the Sun How Long it Takes for Each Planet to Orbit the Sun How Long it Takes for Each Planet to Orbit the Sun If one was asked the questions, οΏ½How long is a day?οΏ½ and οΏ½How long is a year?οΏ½ they would probably be very offended by such a simple question. A day is 24 hours, while a year is 365 days long, 366 during a leap year. In the basic sense, this answer would be correct, but the answer really only applies to Earth. On different planets, there are very different times of what constitutes a οΏ½day,οΏ½ which is the time it takes for a planet to complete one turn of its axis and a οΏ½year,οΏ½ which equivocates to the time it takes a planet to completely orbit around the sun. Planets that are closer to the sun do not take as long to complete their orbit and subsequently have shorter years than our planet. Alternatively, planets that are far away, such as Neptune or Saturn, take a very long time to completely orbit around the sun.

Interestingly enough however, it seems to be the farther a planet is away from the sun, the faster they can complete a turn of their access. This means that although far reaching planets have longer years, their days are actually shorter than EarthοΏ½s. In terms of the four closest planets to the sun, excluding Earth, it can be seen how distance from the planet effects the time it takes for each planet to orbit the sun. Mercury, the first planet in our solar system can completely orbit around the sun in a mere 88 Earth Days, but nearly takes 60 days to complete a turn of its axis. Venus, which is the closet planet to Earth, takes 224 days to orbit around the sun. Oddly enough Venus takes longer to complete a rotation of its axis, 243 days, than it does to completely orbit the sun. Mars, one of the closest planets to Earth in size takes around 686.97 days to orbit around the earth and has a nearly identical day of 24.3 hours. The last four planets of the sun, demonstrate the immense effect of distance on the time it takes for a planet to rotate around the sun.

Jupiter, the solar systemοΏ½s largest planet, takes 4,331.572 days to orbit around the sun, but the fast turning planet only takes 9.8 hours to completely rotate on its axis. Saturn takes more than double the time of Jupiter to orbit the sun with a time of 10,832.33 days, but has nearly an identical time to rotate on its axis with 10.2 hours. Uranus and Neptune are the two farthest planets from the sun and the time it takes for them to orbit around the sun reflects this. Uranus takes 30,7999.09 days to orbit around the sun, which is impressive but cannot compare to the 60,190 days it takes Neptune to complete the same task. However, Uranus and Neptune have comparable rotation times of 17.14 and 16 hours respectively. Next time youοΏ½re asked about how long a year or a day is, make sure to not fall into the boring perspective of only thinking about your planet.

Giving the answer that a year on Neptune is more than 60,000 days or a day on Jupiter is less than 10 hours is a lot more interesting. 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 Planets - Zoom Astronomy Your age on the Planets The Planets (plus the Dwarf Planet Pluto) Our solar system consists of the sun, eight planets, moons, many dwarf planets (or plutoids), an asteroid belt, comets, meteors, and others. The sun is the center of our solar system ; the planets, their moons, a belt of asteroids , comets , and other rocks and gas orbit the sun. The eight planets that orbit the sun are (in order from the sun): Mercury , Venus , Earth , Mars , Jupiter , Saturn , Uranus , Neptune . Another large body is Pluto , now classified as a dwarf planet or plutoid. A belt of asteroids (minor planets made of rock and metal) lies between Mars and Jupiter. These objects all orbit the sun in roughly circular orbits that lie in the same plane, the ecliptic (Pluto is an exception; it has an elliptical orbit tilted over 17° from the ecliptic).

Easy ways to remember the order of the planets (plus Pluto) are the mnemonics: "My Very Excellent Mother Just Sent Us Nine Pizzas" and "My Very Easy Method Just Simplifies Us Naming Planets" The first letter of each of these words represents a planet - in the correct order. The largest planet is Jupiter. It is followed by Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury, and finally, tiny Pluto (the largest of the dwarf planets). Jupiter is so big that all the other planets could fit inside it. The Inner Planets vs. the Outer Planets The inner planets (those planets that orbit close to the sun) are quite different from the outer planets (those planets that orbit far from the sun). The inner planets are: Mercury, Venus, Earth, and Mars. They are relatively small, composed mostly of rock, and have few or no moons. The outer planets include: Jupiter, Saturn, Uranus, Neptune, and Pluto (a dwarf planet). They are mostly huge, mostly gaseous, ringed, and have many moons (again, the exception is Pluto, the dwarf planet, which is small, rocky, and has four moons).

Temperatures on the Planets Generally, the farther from the Sun, the cooler the planet. Differences occur when the greenhouse effect warms a planet (like Venus) surrounded by a thick atmosphere. Density of the Planets The outer, gaseous planets are much less dense than the inner, rocky planets. The Earth is the densest planet. Saturn is the least dense planet; it would float on water. The Mass of the Planets Jupiter is by far the most massive planet; Saturn trails it. Uranus, Neptune, Earth, Venus, Mars, and Pluto are orders of magnitude less massive. Gravitational Forces on the Planets The planet with the strongest gravitational attraction at its surface is Jupiter. Although Saturn, Uranus, and Neptune are also very massive planets, their gravitational forces are about the same as Earth. This is because the gravitational force a planet exerts upon an object at the planet's surface is proportional to its mass and to the inverse of the planet's radius squared. A Day on Each of the Planets A day is the length of time that it takes a planet to rotate on its axis (360°). A day on Earth takes almost 24 hours.

The planet with the longest day is Venus ; a day on Venus takes 243 Earth days. (A day on Venus is longer than its year; a year on Venus takes only 224.7 Earth days). The planet with the shortest day is Jupiter ; a day on Jupiter only takes 9.8 Earth hours! When you observe Jupiter from Earth, you can see some of its features change. The Average Orbital Speed of the Planets As the planets orbit the Sun , they travel at different speeds. Each planet speeds up when it is nearer the Sun and travels more slowly when it is far from the Sun (this is Kepler's Second Law of Planetary Motion ). The Planets in Our Solar System Planet (or Dwarf Planet) In 2005, a large object beyond Pluto was observed in the Kuiper belt. A few astronomers think that there might be another planet or companion star orbiting the Sun far beyond the orbit of Pluto. This distant planet/companion star may or may not exist. The hypothesized origin of this hypothetical object is that a celestial object, perhaps a hard-to-detect cool, brown dwarf star (called Nemesis ), was captured by the Sun's gravitational field.

This planet is hypothesized to exist because of the unexplained clumping of some long-period comet's orbits. The orbits of these far-reaching comets seem to be affected by the gravitational pull of a distant, Sun-orbiting object. Planet Activities and Quizzes What are the orbital lengths and distances of objects in our solar system? How do objects in space travel? What are the orbital lengths and distances of objects in our solar system? Space is huge, and even our immediate environment is gigantic. We are the third planet from the Sun, and the third of three inner planets, all of which are right next to the Sun compared to others. The picture below shows the planets in their orbits on the orbital plane. You have to look carefully to see our home. The four inner planets (Mercury, Venus, Earth and Mars) are in the tiny disk in the center, inside of Jupiter's orbit. Image from The Nine Planets, a Multimedia tour of the Solar System by Bill Arnett The planets are far from the Sun, travel huge distances in space, and take a long time to do so. Pluto takes almost 250 years to go around the Sun completely and travels almost 23 billion miles to do so!

OBJECT The Orbits of the Planets - Worksheet PREVIOUS PAGE THE ORBITS OF THE PLANETS - WORKSHEET The following table gives information about the ORBITS of the NINE planets of the SOLAR SYSTEM. The force of GRAVITY makes the planets move in orbits that are nearly circular around the SUN. THE PLANETS Planet Distance Mass Time for 1 from of Planet Orbit Sun (x10 ^22 kg) of Sun (million km) (days) Mercury 58 33.0 88.0 Venus 108 487 224.7 Earth 150 598 365.2 Mars 228 64.2 687.0 Jupiter 778 190,000 4332 Saturn 1,429 56,900 10760 Uranus 2,871 8,690 30700 Neptune 4,504 10,280 60200 Pluto 5,913 1.49 90600 1.

a. Plot a graph of the DISTANCE from the SUN (on the x-axis) against the TIME for one ORBIT (on the y-axis) for each of the nine PLANETS. Join the points together to produce a SMOOTH curve. b. Write down what you can CONCLUDE from the graph. c. It was once thought that a tenth planet should have an orbit of 420 million km from the Sun. Use your graph to predict how long a YEAR will be on this planet. 2. a. Calculate the SPEED of each of the nine planets using the formulae SPEED = DISTANCE TRAVELLED /TIME 1) Distance travelled around an orbit = 2IIr 2) r = distance from the Sun The best units of speed to use are millions of km per day. Put these in a table THE SPEEDS OF THE PLANETS Planet Distance from sun Speed of planet (millions of km) (million km day -1) Mercury 58 4.14 Venus 108 etc. etc. b. Write down what you can CONCLUDE from this table. c. Newton's Law of Gravitation states that the force of gravity becomes SMALLER the further the planet is from the Sun.

Use this fact and what you know about circular motion to explain why Mercury has such a HIGH speed and why Pluto has such a LOW speed. THE MOONS OF JUPITER Name of Distance Mass of Time for 1 Orbit Satellite from Satellite of Jupiter of Jupiter Jupiter (x10^18) (days) (million km) Sinope 23.70 0.078 758.00 Carme 22.60 0.096 692.50 Elara 11.74 0.78 259.65 Himalia 11.48 9.56 250.57 Callisto 1.88 108,000 16.69 Ganymede 1.07 148,000 7.15 Europa 0.67 48,000 3.55 Io 0.42 89,400 1.77 Amalthea 0.18 7.17 0.50 3.

The above nine moons of JUPITER form a mini-solar system. a. Plot a graph of DISTANCE from Jupiter (on the x-axis) against TIME for one orbit (on the y-axis) for each of the SATELLITES in the above table. Join these points to produce a SMOOTH curve. b. In what way is the curve SIMILAR to the curve for the PLANETS? c. In what way is the curve DIFFERENT from the curve for the planets? d. The radius of SINOPE's orbit around Jupiter is VERY ROUGHLY the same as the radius of Mercury's orbit around the Sun. Explain why Sinope takes so long to complete one orbit whereas Mercury only takes 88 days. 4. Surprisingly, the MASS of the planets does not affect the orbit at all. You should DEMONSTRATE this by plotting a graph of DISTANCE from the Sun (on x-axis) against the MASS of the planet (on y-axis). The points should be in a RANDOM scatter showing that there is NO relation between the two VARIABLES. 5.

JOHANN BODE noticed that if you measure the orbital RADII of the planets in the Solar System in AU (1 AU is the mean distance from the Earth to the Sun) then the radii of the orbits seem to obey a MATHEMATICAL rule called BODE'S LAW. Take the number 0, 3, 6, 12 ... doubling at each step. Add 4 to each number, then divide by 10. This is the predicted radius in AU. a. Check Bode's Law by constructing the following table of Actual Radius (in AU) and radius predicted by Bode's Law for all nine planets THE ORBITAL RADII OF THE PLANETS Planet Orbital Radius Radius from Radius (AU) Bode's Law (million km) Mercury 58 0.39 0.40 Venus 108 0.72 0.70 Earth 150 1.0 etc b. Using his Law, Bode predicted there should be a "missing" planet. What should be the ORBITAL RADIUS of this planet? What would be the TIME it takes to orbit the Sun?

(So convinced were astronomers that this missing planet must exist that it was given the name CERES. In fact there are just ASTEROIDS at this orbital radius) c. If Bode's Law were true, it would have to apply to other planetary systems such as the moons of Saturn and Jupiter. Try to find a RULE that would fit the ORBITAL RADII of moons (the rule R = (n + 10) / 10 where n = 0, 3, 6 .. fits the first few) THE ORBITAL RADII OF THE MOONS OF SATURN Moon of Saturn Orbital Orbital Radius from Radius Radius Rule (thousand km) (Scaled) Mimas 186 1.0 Enceladus 238 1.28 Tethys 295 1.59 Dione 377 Rhea 527 Titan 1,222 Hyperion 1,481 Iapetus 3,561 Phoebe 12,952 N.B. Saturn has at least 25 moons, but most are no more than lumps of rock.

Those above are over 200 km across). CLEARLY, Bode's Law is NOT true in general and it is just COINCIDENCE that the planets orbital radii fall close to his numbers. The Solar System: Mercury | The Institute for Creation Research The Solar System: Mercury Resources › Physical Sciences Resources › Astronomy The smallest planet of our solar system holds some big mysteries for secular astronomers, and it continues to delight creationists. Mercury is only 38 percent the diameter of Earth, making it the smallest and least massive of the eight planets. It is the innermost planet of the solar system, orbiting the sun at a distance of only 36 million miles. That is nearly three times closer to the sun than Earth is. Mercury is a solid, rocky world, with only a trace of an atmosphere. It has mountains, valleys, plains, and craters—lots and lots of craters! In appearance, Mercury resembles a 40 percent larger (in radius) version of the moon. But when it comes to creation research of the early solar system, Mercury provides many interesting clues. The unusual characteristics of this world make for an intriguing study.

A World of Extremes Since it is closest to the sun, Mercury has the shortest “year” of any planet, taking only 88 Earth days to complete one orbit. So every time Earth completes one orbit, Mercury has already made four trips around the sun. On the other hand, it has the longest solar day of any planet. A hypothetical observer on Mercury’s surface would only see a sunrise every 176 Earth days! The “sidereal” (relative to the stars) rotation rate of Mercury is 59 Earth days. If we could somehow watch Mercury through a telescope from a distant star, we would see it rotate one time every 59 days. This is called a “sidereal day” because sidereal means “star,” and we are watching from the stars in this scenario. On the other hand, if we could somehow watch Mercury from the position of the sun, Mercury would appear to turn once every 176 days. This is called a “solar day.” The reason for the difference is that Mercury orbits the sun as it rotates.1 This is also true of the other planets, though the difference is generally much less.2 Mercury’s slow rotation results in some other interesting effects.

A given spot on Mercury is in direct sunlight for about 88 continuous Earth days at a time. And since Mercury is three times closer to the sun than Earth is, and since there is no substantial atmosphere to transport the heat, the surface temperature on the day side of Mercury can reach 800 degrees Fahrenheit—more than hot enough to melt lead. Perhaps even more surprising is that the temperature on the night side of Mercury can drop to -280 degrees Fahrenheit! This is because it is in continual darkness for up to 88 days and there is no significant atmosphere to prevent the nighttime surface from radiating virtually all its heat into space. These extremes lead to some interesting hypothetical scenarios. Suppose your spaceship ran out of fuel, but not before you were able to land near the equator of Mercury. Thankfully, you have landed on the night side (barely), and your spacesuit protects you from the bitter cold surface. But it won’t protect you from the 800-degree daytime temperatures that are about to occur when the sun rises in just a couple of hours! Thanks to Mercury’s very long day, you could begin jogging west at a leisurely pace of two miles per hour.

As long as you can maintain that pace, you could stay ahead of the sunrise and remain safely in the night for as long as it takes for the rescue ship to arrive. Effectively, you would be jogging in the opposite direction that the planet rotates, and at about the same rate, thereby permanently remaining in the safe shadow of night. Mercury’s Strange Orbit Another curious aspect of Mercury’s rotational (sidereal) period is that it is precisely two thirds of its orbital period. So Mercury turns on its axis three times every time it orbits the sun twice. In astronomy, whenever the ratio of two periods can be expressed by a simple fraction, it is called a “resonance.” Mercury is the only planet in our solar system whose rotation period and orbital period are in resonance. There is a reason for this, and it involves Mercury’s orbit. Mercury has the most eccentric orbit of any planet—meaning that its orbit is noticeably elliptical and not as circular as the other planets. From Kepler’s Second Law (see “ The Solar System” article),3 a planet in an elliptical orbit moves faster when closer to the sun than it does when farther away.

The point of closest approach is called perihelion, and this is when Mercury moves the fastest. The most distant point is aphelion, and this is where it orbits the slowest. But Mercury’s rotation rate does not change. Interestingly, when Mercury is near perihelion, its rotation rate essentially matches its revolution rate, such that it keeps the same side pointed at the sun for several weeks.4 This configuration is very gravitationally stable.5 It would be strange to watch this phenomenon from the surface of Mercury itself—if we could somehow survive there. Imagine we begin by watching a very slow sunrise. It takes almost 20 hours between the first moment when the top of the sun peeks over the horizon and the time when the entire sun is visible. The sun seems enormous from Mercury’s perspective—appearing two and a half times larger in the sky than it does on Earth and over six times brighter! The sky remains black even when the sun is up, since Mercury lacks the comfort of Earth’s thick atmosphere. The sun then gradually climbs higher in the sky over the next several weeks. The stars also rise in the east, seeming to move at about twice the speed of the sun.

But as Mercury approaches perihelion, the sun seems to gradually slow its upward path, while the stars continue to rise and set at their usual pace. The sun is now noticeably larger than we witnessed at sunrise and over three times larger than it appears from Earth—and ten times brighter! Then the sun gradually comes to a complete stop and begins to travel slowly backward just slightly for about a week. We might feel like Hezekiah ( Isaiah 38:8 )!6 It then slows to a stop once again and reverses direction once more. The sun then gradually resumes its forward path, shrinking and fading a bit as Mercury moves toward aphelion. The sun eventually sets in the west, roughly three months after sunrise. Observing Mercury Since it is so close to the sun, Mercury appears quite bright in our nighttime sky, rivaling the brightest stars. Yet most people have never seen it. The planet can be a challenge to locate because it orbits so close to the sun and is easily lost in the glare. Most other planets can be seen late at night, when the sky is quite dark.

But not Mercury—it is only visible at twilight and only at certain times of the year when it is in a part of its orbit that appears (in angle) most distant from the sun. This position is called “greatest elongation.” At such times, it is possible to see Mercury just after sunset for “eastern elongations” or just before sunrise for “western elongations.”7 Thanks to Mercury’s short period, greatest elongations happen six (sometimes seven) times a year. Our next chance to see Mercury will be on October 9, 2013, or a few days before or after this. Go outside 20 to 30 minutes or so after sunset and look low to the west, just above the horizon. Venus will also be visible and bright and much higher in the sky. Look between Venus and the point where the sun sets and you will see the much-fainter Mercury. Mercury Confirms Creation Since Mercury is so close to the sun, and only visible low in the sky after sunset or before sunrise, Earth-based telescopic views of Mercury tend to be rather unimpressive and unrevealing.

That all changed when NASA sent the Mariner 10 spacecraft to visit Mercury in 1974. During several flyby encounters, Mariner 10 was able to image much of the day side of Mercury in unprecedented detail. It also measured a substantial magnetic field for this tiny planet. This is disturbing news for secularists who believe that our solar system is billions of years old, because a small planet like Mercury should not be able to maintain a magnetic field for so long. But this doesn’t surprise creationists. Physicist D. Russell Humphreys, Ph.D., has an interesting biblically based model that is able to account for the current strength of planetary magnetic fields based on their true age of about 6,000 years.8 His model lines up quite well with the current measured field strengths of the planets. Dr. Humphreys had also predicted that Mercury’s magnetic field will show measurable decay since the 1974 measurements. And this was confirmed by the more recent (2008-2013) Messenger spacecraft.9 Mercury has also been used to confirm other aspects of science.

Theoretical physicist Albert Einstein’s general theory of relativity indicates that gravitational fields affect the measurement of space and time. One such prediction of relativity is that Mercury’s perihelion should “precess” at a different rate than classical physics would predict. “Precess” means that the ellipse of Mercury’s orbit slowly rotates such that the angular location of the perihelion (and aphelion) gradually changes.10 Observations have confirmed Einstein’s prediction, bolstering our confidence in general relativity. Creationists have long debated when and how the craters we find in our solar system actually happened. Were the planets created with craters? Did God use some process to make the planets on Day Four such that the craters are the last material He brought to impact the surface? Did they happen after the Curse or during the Flood year? And if so, why? Mercury may also hold the key to theories of cratering. Most other rocky worlds in our solar system have tectonic, atmospheric, and volcanic activity that can remove evidence of any previous craters. But not Mercury. Its pristine surface may be a window into the original conditions of our solar system.11 What other secrets can we discern from this fascinating little world?

Time will tell. References To make this easier to understand, suppose that Mercury’s rotation and revolution periods were both exactly the same: 88 days. In this case, a person watching from a distant star would see Mercury rotate once in 88 days. But the sun would never see the other side of Mercury because the planet would keep its same “face” pointed toward the sun as it revolves around the sun. Likewise, a person standing on Mercury’s surface would never see a sunrise or sunset, if this were the case. The sidereal day would be 88 days, and the solar day would essentially be infinity. Since other planets also orbit the sun, their solar days are also different than their sidereal day. But the difference tends to be much smaller than with Mercury. Earth has only a four-minute difference between its solar and sidereal days. The reason Mercury exhibits such an enormous difference is because the length of its sidereal day is comparable to the length of its year. Lisle, J. P. 2013. The Solar System . Acts & Facts. 42 (6): 10-12.

At the time of perihelion, the orbital angular speed actually slightly exceeds the rotation angular speed for about one week. An observer on the surface would see the sun apparently move slightly backward in the sky for that one week. Some orbital resonances are stable and self-correcting, such as Mercury’s. Others are unstable, such that an orbiting body will be continually perturbed until it is ejected into a different orbit altogether. This appears to be the reason why there is a deficit of asteroids having simple resonances with Jupiter’s orbit. These resonance orbits are known as the Kirkwood gaps. Critics sometimes declare that God cannot do certain things, such as make the sun go backward as He did for Hezekiah. Such things are simply not possible, we are told. Yet this happens every three months on Mercury. It is probably not the same mechanism that God used for Hezekiah. Nonetheless, it is to the shame of those critics who attempt to tell God what He cannot do. “Eastern” denotes that Mercury is east of the sun. It therefore can be seen in our western sky just after sunset. Conversely, “western” elongations are those in which Mercury is farthest separated to the west of the sun.

At such a time, Mercury can be viewed in the eastern sky just before sunrise. Thomas, B. Mercury’s Fading Magnetic Field Fits Creation Model . Creation Science Update. Posted on icr.org October 30, 2011, accessed June 1, 2013. The perihelion distance does not change, only its angle. Imagine Mercury’s orbit lined up with a clock such that the perihelion is aligned with 12:00 and the aphelion is aligned with 6:00. As Mercury orbits the sun, the ellipse of its orbit slowly rotates counterclockwise such that at a later time perihelion would point to 11:30 and aphelion would point to 5:30. The precession of Mercury’s orbit is very slow, amounting to only 575 arc-seconds per century. Of this rate, 532 arc-seconds per century are due to gravitational perturbations of the other planets. The remaining 43 arc-seconds per century are due to the effects of general relativity. The agreement between the theoretical predictions and the observations is remarkable. 11.

This may also be true of the moon. Yet some creationists believe that the moon was impacted more recently by comets or a meteor stream in association with the Flood of Genesis 6 -8. It is unlikely that Mercury would have been strongly affected by the Flood due to its great distance. So differences between Mercury and the moon may help us understand better when these events occurred. * Dr. Lisle is Director of Physical Sciences at the Institute for Creation Research and received his Ph.D. in Astrophysics from the University of Colorado. Cite this article: Lisle, J. 2013. The Solar System: Mercury. Acts & Facts. 42 (8): 10-12.

Question: Which planet in our solar system takes the shortest time to orbit the sun?
Answer: Mercury