Author: Jerry Coffey

We all known that Saturn has rings, but does Jupiter have rings? Yes, it does. Four planets have a rings system: Saturn, Jupiter, Uranus, and Neptune. Saturn is best know because it has the brightest and most extensive rings system in the Solar System.

The rings around Jupiter had never been seen before Voyager 1 arrived in 1979. Since then the rings have been observed by the largest telescopes on Earth, the Hubble Space Telescope, and the New Horizons spacecraft. So far, only four rings have been observed: the halo ring, the main ring, the Amalthea gossamer ring, and the Thebe gossamer ring.

Jupiter’s rings and moons exist within an intense radiation belt of electrons and ions trapped in the planet’s magnetic field. These particles and fields comprise the Jovian magnetosphere or magnetic environment, which extends 3 to 7 million km toward the sun, and stretches in a windsock shape at least 750 million km, which puts it inside of Saturn’s orbit.

The main ring is about 7,000 km wide and has an abrupt outer boundary 129,130 km from the center of the planet. The main ring encompasses the orbits of two small moons, Adrastea and Metis, which may act as the source for the dust that makes up most of the ring. The ring needs a constant source of dust because small particles can only exist for 100 to 1000 years. The dust is thought to rise from moons within the rings due to micrometeoroid impacts. The main ring merges gradually into the Halo ring. The halo is a broad, faint torus of material about 20,000 km thick and extending halfway from the main ring down to the planet’s cloudtops.

On the outer edge of the main ring and opposite of the halo ring, is the broad and extremely faint Amalthea gossamer ring. This ring extends out beyond the orbit of the moon Amalthea. Scientists believe that it is composed of dust particles smaller than 10 microns. 10 microns is about the size of cigarette smoke particles. It extends to an outer edge of about 129,000 km from the center of the planet and inward to about 30,000 km. The origin of the ring is probably from micrometeorite bombardment of the tiny moons orbiting within the ring. Last, is the Thebe gossamer ring. This is the faintest of the Jovian rings and extended from the orbit of the moon Thebe at about 226,000 km towards the planet, ending at about 129,000 km. The exact inner edges of the two gossamer rings are hard to define because they overlap the brighter main ring.

So, the answer to ”does Jupiter have rings” is yes, it has four known rings. Be sure to read about the ring systems of Neptune and Uranus as well.

Here’s a news article from Universe Today about the rings of Jupiter, and information about New Horizon’s observations of Jupiter’s rings.

Here’s NASA’s Solar System explorer information about Jupiter’s rings, and a cool image from Astronomy Picture of the Day of Jupiter’s rings.

We’ve also recorded an entire show just on Jupiter for Astronomy Cast. Listen to it here, Episode 56: Jupiter, and Episode 57: Jupiter’s Moons.

Source:
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiter&Display=Rings

The diameter of Jupiter at its equator is 142,984 km. Since it rotates very quickly, completing a full rotation in just 10 hours, it is an oblate spheroid and bulges at the equator. If you measure the diameter through the poles it is 9,276 km smaller at 133,708 km. Solely based on diameter, Jupiter is 11.2 times the size of the Earth and larger than any other body in our Solar System other than the Sun.

The diameter of Jupiter is amazingly large for our Solar System, but is easily eclipsed by some extrasolar planets. According to Dr. Sean Raymond at the Center for Astrophysics and Space Astronomy at the University of Colorado the largest terrestrial(rocky like Earth) planets can be up to 10 times the size of Earth. Since Jupiter is a gas giant, let’s compare apples to apples and talk about the largest known gas giant in the universe. As of this time(August, 2011) the largest gas giant known is TrES-4. This planet is 1,400 light years away in the constellation Hercules. It has been measured to be 1.4 times the size of Jupiter, but it only has 0.84 times Jupiter’s mass. A gas giant can get about 14 times more massive than Jupiter before they ignite fusion and become brown dwarf stars.

A common question that people ask is ”can Jupiter ever become a star?”. That is a reasonable question given its size and mass. Fortunately for humans, the answer is no. Jupiter would need to add about 80 times its current mass in order to ignite fusion. While the planet occasionally accretes more matter, there is not enough available in our Solar System to add that much mass. If it did ignite, it would scorch our world

Jupiter interests scientists for many reasons. Its moons are a major draw for research. The planet has 64 moons that have been confirmed and a few more that have rarely been observed. The moons in the Jovian system account for 50% of all of the moons in our Solar System. A few of those moons are larger than some dwarf planets and others show evidence of subsurface oceans. Scientist are not sure if they are oceans of water as we know it, but they do believe that they exist.

The diameter of Jupiter is an awesome number in itself, but, once you consider the planet as a whole, you see that knowing the diameter is just scratching the surface. Hopefully, it is enough to spark an interest in researching the planet further.

Here’s more information on the diameter of Earth, if you’d like to compare and see how big Jupiter really is. Jupiter’s big, but extrasolar planets are thought to be able to get even bigger. Here’s an article about how big planets can get.

As I’ve mentioned above, Jupiter is the biggest planet in the Solar System, and here’s Hubblesite’s News Releases about Jupiter.

We’ve also recorded an entire show just on Jupiter for Astronomy Cast. Listen to it here, Episode 56: Jupiter, and Episode 57: Jupiter’s Moons.

Sources:
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Jupiter&Display=OverviewLong
http://planetquest.jpl.nasa.gov/news/tres4.cfm

The Universe Today readers are always asking great questions. ”How long is a day on Jupiter?”, is one of them. A day on Jupiter, also known as the sidereal rotation period, lasts 9.92496 hours. Jupiter is the fastest rotating body in our Solar System. Determining the length of a day on Jupiter was very difficult, because, unlike the terrestrial planets, it does not have surface features that scientists could use to determine its rotational speed.

Scientists cast about for ways to judge the planet’s rotational speed. An early attempt was to do some storm watching. Jupiter is constantly buffeted by atmospheric storms, so the theory was that you could locate the center of a storm and get some idea of the length of a day. The problem scientists encountered was that the storms on Jupiter are very fast moving, making them an inaccurate source of rotational information. Scientist were finally able to use radio emissions from Jupiter’s magnetic field to calculate the planet’s rotational period and speed. While other parts of the planet rotate at different speeds, the speed as measured by the magnetosphere is used as the official rotational speed and period.

All of the planets are oblate spheroids with varying degrees of flattening. Jupiter’s extremely fast rotation flattens it more than any other planet. The diameter of the equator is 9275 km more than the distance from pole to pole. Another interesting effect of Jupiter’s rotational speed is that, because Jupiter is not a solid body, its upper atmosphere features differential rotation. The atmosphere above the poles rotates about five minutes slower than the atmosphere at the equator.

Jupiter is almost a solar system unto itself. Many astronomers believe the the planet is simply a failed star, just lacking the mass needed to ignite fusion. Many people are aware of its four largest moons, the Galilean moons Io, Europa, Ganymede, and Callisto, but few realize that Jupiter has 50 confirmed moons and at least 14 provisional moons. The four largest moons are all very interesting to scientists. Io is a volcanic nightmare. Europa is covered in water ice and may have oceans of slushy ice underneath. Ganymede is the largest moon in the Solar System, even bigger than Mercury, and is the only moon known to have an internally generated magnetic field like Earth’s. Callisto is interesting because its surface is thought to be very ancient; perhaps original material from the birth of the Solar System.

Knowing ”how long is a day on Jupiter” just scratches the surface of the intrigue that is the Jovian system. You could spend months researching the planet and its moons, yet have more to research to do.

Here’s an article on Universe Today that shows how Jupiter can be very flattened, and an article about how the powerful windstorms are generated from its rotation.

NASA’s Ask an Astronomer also has an answer for the question, “how long is a day on Jupiter?” And a cool video of Jupiter’s rotation.

We’ve also recorded an entire show just on Jupiter for Astronomy Cast. Listen to it here, Episode 56: Jupiter, and Episode 57: Jupiter’s Moons.

Sources:
NASA
Caltech Cool Cosmos

Mars dust storms are much different than the dust devils that many people have seen in images sent back from the planet. On Mars a dust storm can develop in a matter of hours and envelope the entire planet within a few days. After developing, it can take weeks for a dust storm on Mars to completely expend itself. Scientists are still trying to determine why the storms become so large and last so long.

All Mars dust storms are powered by sunshine. Solar heating warms the Martian atmosphere and causes the air to move, lifting dust off the ground. The chance for storms is increased when there are great temperature variations like those seen at the equator during the Martian summer. Because the planet’s atmosphere is only about 1% as dense as Earth’s only the smallest dust grains hang in the air.

Surprisingly, many of the dust storms on the planet originate from one impact basin. Hellas Basin is the deepest impact crater in the Solar System. It was formed more than three billion years ago during the Late Bombardment Period when a very large asteroid hit the surface of Mars. The temperatures at the bottom of the crater can be 10 degrees warmer than on the surface and the crater is deeply filled with dust. The difference in temperature fuels wind action that picks up the dust, then storm emerge from the basin.

The dust storms were of great concern when probes were first sent to Mars. Early probes happened to arrive in orbit during large events. The Viking missions of 1976 easily withstood two big dust storms without being damaged. They were not the first missions to survive Martian dust storms. In 1971, Mariner 9 arrived at Mars during the biggest dust storm ever recorded. Mission controllers simply waited a few weeks for the storm to subside, then carried on with the mission. The biggest issue that rovers face during a dust storm is the lack of sunlight. Without the light, the rovers have trouble generating enough power to keep their electronic warm enough to function.

Mars dust storms are of great interest to scientists. Even though several spacecraft have observed the storms first hand, scientists are no closer to a definitive answer. For now, the storms on Mars are going to continue to present challenges to planning a human mission to the planet.

Here’s an article describing how the dust storms threatened the Mars rovers, and another discussing how electrical dust storms could make life on Mars impossible.

Here’s one of the best articles from NASA about the dust storms, and another gallery from NASA/JPL.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
http://science.nasa.gov/science-news/science-at-nasa/2003/09jul_marsdust/
http://www.jpl.nasa.gov/news/news.cfm?release=2007-080
http://science.nasa.gov/science-news/science-at-nasa/2001/ast16jul_1/

Mars rotation is 24 hours, 39 minutes, and 35 seconds if you are interested in the solar day or 24 hours, 37 minutes and 22 seconds for the sidereal day. Since the planet only rotates about 40 minutes slower than Earth, this is one category where the two planets are not very different. Mars, like all of the planets except Venus, rotates in prograde(counter clockwise). The planet has a rotational speed of 868.22 km/h at the equator. The similarity if the length of the day allows the engineers as NASA to switch their day to a ”Mars day” when they are working with rovers on the planet. This maximizes their time with the equipment, but drastically changes their actual Earth schedule. They end up working an ever changing day as the Martian/Earth day difference accumulates.

Mars is a well studied planet. As a matter of fact, it is the best understood planet in our Solar System other than our own. There are currently(July 2011) 6 missions either in orbit or on the planet’s surface. With all of the data accumulated, Mars rotation is only one of thousands of facts known about the planet. Here are a few more.

Multiple missions to Mars have found evidence of water ice and carbon dioxide ice under the planet’s surface. How do scientists know the difference? When the ice is exposed to the Martian atmosphere, carbon dioxide ice(dry ice) will melt and vaporize quickly, in one day or less. Water ice will take up to four days. The other way is to heat a sample in one of the tiny ovens aboard a rover. The spectrometer on the rover will then be able to detect H₂O in the gases that the sample releases.

Mars has a reddish appearance because it is covered in rust. Well, iron oxide dust. That dust is every where. Mars has large dust storms that can sometimes cover the entire planet, so that dust is in the air as well. During global dust storms it is impossible to optical observe the surface.

Mars has not had plate tectonics for billions of years, if ever. The lack of plate movement allowed volcanic hotspots to spew magma onto the surface for millions of consecutive years. Because of these uninterrupted eruptions, there are many large volcanic mountains on Mars. Olympus Mons, on Mars, is the largest mountain in the Solar System.

Those are just a few teaser facts. I wish I had more space to keep going, but we have hundreds of more articles about Mars here on Universe Today and do not forget to check out NASA’s website. Good luck with your research.

Here’s an article about how crater impacts measure the ancient equator of Mars. How long is a day on Mars?

Enjoy some Mars facts from NASA, and Hubblesite’s News Releases about Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Source: NASA

Mars mass is 6.4169 x 10²³ kg. That is slightly more than 10% of the Earth’s mass. Mars is a tiny world in every way when compared to Earth. In our Solar System, Mars is the second smallest planet by mass. Only Mercury is smaller. While Mars is a tiny planet, it is the most explored outside of our own. Here are a few Mars missions and some of the discoveries that each made.

Mariner 3 and 4 were meant to be sister missions to Mars. Mariner 3 failed shortly after launch, but Mariner 4 arrived in Martian orbit after an 8 month journey. It is credited with returning the first images from another planet. It was able to show large impact craters that appeared to have frost on them. The spacecraft and its equipment were crude by modern standards.

We will skip a few missions and move to the Phoenix Lander. This mission’s objective was to confirm the presence of water ice underneath the Martian surface. This water ice had been theorized for quite some time, but lacked confirmation. On June 19, 2008, NASA announced that bits of bright material in a trench dug by the lander’s robotic arm had disappeared over the course of four days. This implied that they were composed of water ice. Initially, they were thought to be water ice or carbon dioxide ice(dry ice) In the conditions on Mars dry ice would have disappeared much faster. Phoenix later confirmed the presence of water ice on Mars using a mass spectrometer. When a soil sample was heated, water vapor appeared as the sample heated to 0 degrees Celsius.

The Mars Express is one of several spacecraft currently exploring Mars. It has sent back images and data the strongly suggest that the Martian environment is much different today than it was a few billion years ago. Interpretation of the data shows that Mars was once a warm and wet world with rivers and oceans dotting its surface. No evidence of past vegetation or life has been found, but proof of liquid water in the planet’s past is intriguing enough.

Knowing Mars mass is enough to answer one question on a test or in a paper, but, to understand the planet, you will have to do quite a bit more research. You will not be alone. NASA scientists are planning at least four more missions by 2020 including a mission to return samples of the Martian soil. The goal is to understand Mars well enough to send a manned flight to the Red Planet.

Here’s a great article about how difficult it will be to land large loads on Mars.

This site lets you calculate your weight on other worlds. And here’s NASA’s fact sheet on Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
NASA: Mars Facts
NASA: Mars Missions

Mar’s surface is a dry, barren wasteland marked by old volcanoes and impact craters. The entire surface can be scoured by a single sand storm that hides it from observation for days at a time. Despite the formidable conditions, Mar’s surface is better understood by scientists than any other part of the Solar System, except our own planet, of course.

Mars is a small world. Its radius is half of the Earth’s and it has a mass that is less than one tenth. The Red Planet’s total surface area is about 28% of Earth. While that does not sound like a large world at all, it is nearly equivalent to all of the dry land on Earth. The surface is thought to be mostly basalt, covered by a fine layer of iron oxide dust that has the consistency of talcum powder. Iron oxide(rust as it is commonly called) gives the planet its characteristic red hue.

In the ancient past of the planet volcanoes were able to erupt for millions of years unabated. A single hotspot could dump molten rock on the surface for millenia because Mars lacks plate tectonics. The lack of tectonics means that the same rupture in the surface stayed open until there was no more pressure to force magma to the surface. Olympus Mons formed in this manner and is the largest mountain in the Solar System. It is three time taller than Mt. Everest. These runaway volcanic actions could also partially explain the deepest valley in the Solar System. Valles Marineris is thought to be the result of a collapse of the material between two hotspots and is also on Mars.

The Martian surface is dotted with impact craters. Most of these craters are still intact because there are no environmental forces to erode them. The planet lacks the wind, rain, and plate tectonics that cause erosion here on Earth. The atmosphere is much thinner than Earth’s so smaller meteorites are able to impact the planet.

Mar’s surface is believed to be much different than it was billions of years ago. Data returned by rovers and orbiters has shown that there are many minerals and erosion patterns on the planet that indicate liquid water in the past. It is possible that small oceans and long rivers once dominated the landscape. The last vestiges of that water are trapped as water ice below the surface. Scientists hope to analyze some of that ice and discover hidden Martian treasures.

How seasonal jets darken the surface of Mars, and how ice depth varies across Mars.

Want to explore the surface of Mars, check it out with Google Mars. Here is some more information about surface features on Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Mars
http://search.nasa.gov/search/search.jsp?nasaInclude=mars+planet