Callisto
By: Briana F.
What is Callisto?
Callisto is one of the four Galilean satellites that orbit the planet Jupiter. It is known as Jupiter's dead moon. The reason why they call it Jupiter's dead moon is because, it has hardly any geologic activity. It has the lowest density out of all of the Galilean Moons. Callisto is also the most heavily cratered object in our solar system.
Discovery of Callisto
The person who discovered it all was Galileo Galilei. On January 7, 1610 he had discovered it, along with 3 other moons. Galileo had named it Jupiter IV, until the mid 1800's when they had named it after the daughter of Lycaon, because there was so many new moons being discovered. Being one of the first moons found revolving around a planet other than Earth, it led to finding out that all of the planets revolve around the sun and not Earth.
Characteristics of Callisto
Since Callisto is the most heavily cratered objects in our solar system, it has a very unique outer layer. They believe that it hasn't changed in anyway for over 4 billion years; which they think makes it about 4.5 billion years old. Astronomers found out that it does not have any plate tectonics or volcanoes, so all of the craters are caused mostly by meteors. On the outer layer, they noticed that it has icy peaks, and also that it is made up of ice, water, and rock. Since Callisto is out of the radiation belt from Jupiter, it has a good enough place to sustain life. The atmosphere of Callisto is very thin, but it has Carbon dioxide, and they believe that it could have molecular oxygen. With further research, they now believe that under Callisto's icy surface that it could have an ocean underneath; possibly sustaining life.
Youtube Video
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Jupiter's Moons: Crash Course Astronomy #17
Sources
Dunford, Bill. "Solar System Exploration." N.p., n.d. Web. 3 Dec. 2015. <http://solarsystem.nasa.gov/planets/callisto>.
Mckinnon, William B. "Callisto." The World Book Encyclopedia. Vol. 3. Chicago, IL: World Book, 2009. 68-69. Print.
Zimmermann, Kim Ann. "Callisto: Facts About Jupiter's Moon." Space.com. N.p., 5 July 2012. Web. 7 Dec. 2015.
Callisto Diagram. Digital image. Wikimedia. N.p., 2 Oct. 2015. Web. 11 Dec. 2015.
Callisto Moon. Digital image. Bing, 2015. Web. 11 Dec. 2015.
Galilean Satellites. Digital image. Planet Wallpaper. N.p., n.d. Web. 11 Dec. 2015.