Science for Thought

Jupiter

Jupiter

Jupiter is the most interesting planet in our solar system, but it's also a big mystery. There are many things about Jupiter that have been revealed by the Cassini probe and, most recently, the Juno probe.

What do astronomers know about this enigma?

Jupiter is the largest gas giant in our solar system and has a radius of 69,911 kilometers. If Earth were the size of a nickel, Jupiter would be the size of a basketball. Jupiter orbits at 5.2 AU (astronomical units) from the Sun or 778 kilometers. One AU is equal to the distance from the Earth to the Sun. Since its axis is only tilted 3% Jupiter has no seasons. Jupiter's day is only 10 hours, which means that it spins the fastest of any planet in the solar system.
Approximately 4.5 billion years ago, Jupiter formed out of the hydrogen and helium that was left over from the Sun's formation. What we see when we look at Jupiter is the outer clouds that are spinning so fast they form bands that in some cases spin opposite to the plant's spin. This is caused by differential rotation in which the poles are rotating 5 minutes longer than the layers at the equator.

One of the most prominent, and the strongest in the solar system, storms is the giant Red Spot. This storm has been chugging away for hundreds of years. However, it has shrunk in size since its discovery. It is possibly a permanent feature of Jupiter. These storms in Jupiter's atmosphere cause lightening just like on Earth, but it's much more powerful ligtening. The clouds on Jupiter are supposedly made from ammonia and water vapor; although, these materials don't make up all that much of the mass of Jupiter.

Jupiter has rings, three of them, but they are very dim compared to the rings of Saturn. Jupiter's rings lie within the intense radiations belts that lie around Jupiter. The radiation near Jupiter is lethal to both us and to probes.

The pressure in Jupiter's atmosphere is so high (a billion times the Earth's atmospheric pressure) it literally compresses hydrogen into what is termed a metallic form of gas. This metallic hydrogen acts as a metallic core that lies under an opaque black ocean of liquid hydrogen, and since Jupiter is spinning rapidly enough this metallic hydrogen core helps to form the strongest magnetosphere in the solar system. This huge magnetic shield extends out as much a 3 million kilometers. That's because metallic hydrogen has its electrons broken loose and shared among the hydrogen atoms, which promote conductivity. However, astrophysicists are not sure what actually creates the magnetosphere. It's possible that a solid iron, rocky core is responsible. There is a possibility that this core could also contain ice.
Some new data from Juno indicate the strength of Jupiter's magnetosphere may be as high as 6 gauss. Earth's is only around 0.65 gauss. Also, fluctuations as much as 2 gauss suggest that the magnetosphere is being created from processes in the atmosphere not the core.

Metallic hydrogen is theoretical because it has not yet been created in the lab. If discovered, it would be yet another holy grail of science.

Scientists believe that the powerful storms in Jupiter's atmosphere create lightening mush stronger than in Earth's atmosphere, and this lightening creates diamonds from the 1% concentration of methane in Jupiter's atmosphere, which is mostly hydrogen. These diamonds fall like hail and eventually become liquid diamonds. This has been demonstrated in the lab.

One thing is certain: Jupiter is hot, maybe hotter than once realized. Recent measurements of Jupiter's temperature suggest this is the case. No one knows for sure what's really going on because there is no way to penetrate down through Jupiter's massive cloud layers. The Galileo spacecraft dropped a probe into Jupiter's upper atmosphere but it only descended 158 kilometers before being overheated. That's only half way down through Jupiter's stratosphere. The atmosphere is at least 1000 kilometers thick. Again, this is not an exact measurement because there is no way to determine where the atmosphere ends and the ocean of opaque hydrogen begins.

There is no doubt that Jupiter has a magnetosphere because the probes have detected very bright auroras at Jupiter's poles. They are much brighter than those on Earth. Some astronomers believe that these auroras are being fed from the volcanic eruptions on Jupiter's moon Io. The volcanic eruptions on that moon are spewing sulfur dioxide into Jupiter's poles to enhance the aurora displays. Also, Jupiter is the hottest planetary radio source in the solar system because of its rapid rotation and its strong magnetosphere. This is solid evidence for the existence of a strong magnetosphere around Jupiter.

Jupiter is considered to be a companion star that never ignited because it's too small. Most stars are part of binary or larger systems. Our sun is an exception. Jupiter might have been a star if our sun had not used up most of the hydrogen and helium when it formed. Arthur C. Clark made it into a star in his '2010' novel. Making Jupiter ignite would have required pumping billions of kilograms of mass into it, and it would have had to be hydrogen. That's hard to imagine. But, even if the aliens in 2010 were able to do it the resulting star would be a red dwarf at best, which wouldn't have been that bright, not nearly as bright as the one they showed in the movie version.

The most interesting aspect of Jupiter is it's moons, but that's for another post.

Thanks for reading.