- 3334 - JUPITER - Four Moons of Jupiter. You can see these four moons of Jupiter with your binoculars. These four moons were first seen by Galileo using his primitive telescope over 400 years ago. The 4 largest moons orbiting Jupiter are Io, Europa, Ganymede, and Callisto discovered in 1610. It was not until 1892 that the 5th moon was discovered.
--------------------- 3334 - JUPITER - Four Moons of Jupiter
- The Pioneer spacecraft visited Jupiter in 1970. The Voyager spacecraft in 1979. The Cassini and Galileo spacecraft in 1990. By 1999 the total count for the Jupiter moons exceeded 60.
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- Io is the closest moon, 262,000 miles from Jupiter‘s surface.. The tidal effects of Jupiter’s enormous gravity puts tremendous stresses on the inner moons. As a consequence Io has a molten interior that is evidenced by its giant volcanoes. There is molten silicate and lava all over the surface.
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- The largest volcanoes are 25 miles in diameter. The jets from these volcanoes spew material 300 miles above the surface. This is higher than the orbit for the space shuttle. The material in the jets is spewing out at half the escape velocity.
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- Io is a bit larger than our Moon. Like our Moon it always points the same surface toward the planet. The tidal force and the gravity of the other moons cause Io to have a wide elliptical orbit. These forces can raise and lower the surface crust by 330 feet. For comparison, on Earth the water tides can raise and lower up to 60 feet, that’s water not solid ground.
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- Io has a thin atmosphere mostly of sulfur dioxide gas. It has very little if any water. It does have a small magnetic field of its own. It’s orbit cuts across Jupiter’s massive magnetic fields and can generate up to 400,000 volts across the surface of Io creating electric currents of up to 3,000,000 amperes. These electric fields create lightning bolts in Jupiter’s upper atmosphere.
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- The sweeping magnetic fields actually remove material from Io’s surface. Up to a ton of material every second. This material becomes an ionized plasma in Jupiter’s atmosphere.
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- Io’s magnetic field is probably created by salt water circulating under the ice. Io has 64% reflectivity due to its icy surface. Its surface temperature is -160 C, -220 C at the poles. The ice is 6 to 19 miles thick. The liquid water below the ice has a total volume of twice the ocean water on Earth.
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- Europa is a perfect sphere with no craters. It has a top crust that is only 3 miles thick, below is ice that is 30 miles thick, then liquid ocean. The crust and ice have giant cracks that may go all the way down to the liquid water. There may be liquid water coming to the surface then freezing.
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- There is oxygen is Europa’s atmosphere created by the Sun’s ultraviolet radiation splitting water ice at its surface into oxygen and hydrogen gases. The hydrogen is not heavy enough to remain in the atmosphere and it escapes into space.
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- Until 1970’s science thought that all life depended on the energy coming directly from the Sun. In 1977 that idea was shattered by discoveries of living bacteria in deep ocean volcanic vents.
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- These bacteria derived their energy from hydrogen sulfide gas bubbling out of the volcanic vents in the ocean floor. Colonies of exotic animals are living in this food chain. Blind shrimp, giant white crabs and red-lipped tube worms that apparently lack a digestive system.
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- This life is thriving in temperatures reaching 750 F, water hot enough to melt lead. The pressure at that depth is 500 times atmospheric pressure. This pressure is what keeps the water from boiling.
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- Toxic chemicals form highly acidic water. The blazing hot mineral rich fluid is expelled into icy cold water creating a smoke that builds towering chimneys of metal ore some 20 feet tall.
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- These same conditions could be found on Europa making it one of the most likely candidates for finding extraterrestrial life in our Solar System. There could be life in the deep oceans of Europa.
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- If we were going to search for life somewhere else in our Solar System, where would it be? At first glance Europa would not be a good choice. The radiation is so intense it would kill you in 10 minutes, the temperature is -300 F, the atmosphere almost does not exist. Where is there a possibility for life?
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- Europa is smaller than our Moon. It is only 1,940 miles across. So, why Europa?
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- Because, beneath it’s icy surface Europa has a warm global ocean with more liquid water the we have on Earth.
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- We have been to Mars 12 times and have found no signs of life. Not even a clear sign of water, but, recent evidence allows hopes for underground water. Apparently, Mar’s surface water dried up millions of years ago.
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- Europa has had Pioneer, Voyager (1979), Galileo (1995), and Cassini spacecraft make flybys.
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- The surface of Europa is bizarre with unusual cracks all over the moon. Some cracks are 2,000 miles long and perfectly straight. Other cracks have arcs and bowl shapes. The sky above the surface is pink and salmon-colored with swirling red storms. It is below the surface that is even more interesting.
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- Indications are the Europa’s surface may be porous-like Artic ice sheets less that 10 miles thick. The liquid water below is a rich soup of organic chemicals and oxygen. These essential elements have percolated down, seeding the underlying ocean with the building blocks for life. This scenario is very similar to the deep ocean volcanic vents in the Pacific where new life was discovered here on Earth not too long ago.
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- If life can exist, a lot depends on the thickness of the ice. It could be a protective cover. Or, it could be a killing lid.
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- As Europa orbits Jupiter the intense gravity creates tides that bulge and bend the moon creating internal friction which creates internal heat. This heat keeps the liquid ocean from freezing. The liquid erupts to the surface and covers the impact craters that would otherwise be on the surface of the moon.
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- If you look at another Jupiter moon, Io, you see this dynamic geology affecting its rocky surface. Volcano’s, geysers, lava flows are covering the entire surface of Io. Europa may have the same rocky core in the same condition. It just happens to be covered by a deep ocean and a sheet of ice.
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- If our volcanic vents in the Pacific are supporting life, maybe Europa’s volcanic vents are doing the same thing. It will be an amazing discovery if it happens. There are missions planned to go see if robots can drill through the ice, send instruments into the ocean, and radio back to Earth what it finds. Europa may be astronomer’s first Eureka.
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- Ganymede would be a planet if it were circling the Sun instead of Jupiter. It is bigger that the planet Mercury. It is 3,300 miles in diameter. But, Ganymede has no atmosphere. It is highly cratered from meteorites with valleys and mountains and some water ice. It has a magnetic field and must have an iron core. Like Europa it could have liquid water oceans under its surface.
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- Callisto is the second largest Jupiter moon, almost the size of Mercury. It is totally covered with craters. In fact any new crater will be made on top of an existing crater. Some craters have ring like patterns extending out like a rock thrown into a pond.
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- Callisto is far enough away from Jupiter that the tidal forces do not cause tidal heating like the other three moons. However, it is still tidally locked with the same surface always facing the planet. It takes 16.7 days to orbit Jupiter.
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- Callisto may also have a liquid water ocean 16 miles below its surface. It has a thin atmosphere of carbon dioxide with some oxygen. Callisto is also outside the radiation influences of the giant planet and would likely be a good base for a NASA mission to explore this planetary system.
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- November 8, 2021 JUPITER - Four Moons of Jupiter 1175 1152 3334
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