Callisto

= = //**Callisto **// Edited by: Adrian Bayaua (Spring 2012) Edited by: Laura Navarro-Molina (Fall 2016)

Callisto is one of Jupiter's 8 satellites, and the second biggest. It is the outermost of Galilean moons and the third largest. It is known to be the most cratered object in our Solar System. It is also considered to be the oldest surface. Callisto is about 4.5 billion years old, about the same age as Jupiter. It is very old like the highlands of the Moons and Mars. It was discovered by Galileo Galilei and Simon Marius in 1610. The surface has not changed since initial impacts molded its surface 4 billion years ago. Callisto seems to have little internal structure; however there are signs from recent Galileo data that the interior materials have settled partially, with the percentage of rock increasing toward the center. Callisto is about 40% ice and 60% rock/iron.

 The myth regarding [|Callisto] was about a, beloved of Zeus and hated by Hera. Hera changed her into a bear and Zeus then placed her in the sky as the constellation. According to some sources Artemis herself killed the bear that was once Callisto, but it is usually accepted that when Arcas was out hunting as a young man he encountered the bear. Callisto recognized the handsome youth as the son she could not raise herself. Forgetting her present form, she tried to come near him, but her loving mother's arms were now strong, furry paws, and her once soothing voice was now a rumbling growl. The bear scared Arcas, and he took aim at her with his spear. Zeus took pity on his former victim and intervened. He placed Callisto in the sky as the constellation Ursa Major, or "great bear," and then took Arcas and placed him in the sky near his mother as Ursa Minor, the "little bear".

NinePlanets.org




 * Author:** Bill Arnett
 * Last Updated:** November 20, 2001
 * Date Reviewed:** May 1, 2012
 * Reviewed By:** Adrian Bayaua
 * Date Reviewed:** Dec 07, 2016
 * Reviewed By:** Laura Navarro-Molina

The website information contains many different types of information about Callisto. It shows it's main facts and contains images of Callisto in many different point of views. The page gives information about Callisto's surface temperature and its composition. It also give a little background of the Myth behind Callisto. The website provides links to different pages of more miscellaneous information about the planet.

The page is very accurate and has very well stated information.The audience is basically the students and the public who want to know more about Callisto and it's features. The information is basic and easy for anyone to read. And the information is very well organized.

It's very easy for anyone to find out more and get into more detail of what certain words mean. There are highlighted key words on the site that you can actually click that can lead you to an extension to another page to find out more about what the key words define and can give you a better understanding. Certain links are external to it's own site and some to a different site.

[|SolarSystem.nasa.gov]




 * Author:** Kristen Erickson
 * Date Reviewed:** May 9, 2012
 * Reviewed By:** Adrian Bayaua
 * Date Reviewed:** Dec 07, 2016
 * Reviewed By:** Laura Navarro-Molina

This website provides a brief, but very plentiful information about Callisto and it's features. It gives information about it's origin and discovery, and how Callisto got it's name. It also includes many different types of images of Callisto including actual photos taken by space probes, illustrated images, and pictures comparing the size of Callisto to other planets or moons in our Solar System.

The information on the page seems very accurate. The audience is the students and the public. The page gives a kind of short but very accurate overview of Callisto and is very easy to read.You can easily find out more about the planet and other side information. The page includes tabs that are easily accessible to other information about Callisto. There are not many pages beyond the home page and they are not external to any other site.

[|SeaSky.org]




 * Date Reviewed:** May 15, 2012
 * Reviewed By:** Adrian Bayaua
 * Date Reviewed:** Dec 07, 2016
 * Reviewed By:** Laura Navarro-Molina

The website gives a lot of information about Callisto and different facts about it as well. On the page, many photos are provided giving an ideal image of what Callisto looks like externally. It explains about Callisto's size and what it mainly orbits, information about it's surface texture and composition, and it's orbital period around Jupiter. This page also gives a brief description of the myth behind it, and the Nymph that Callisto was named after.

The information on the web page seems to be highly accurate and is up to date. Information provided is detailed and seems to be reliable. The audience is students and any other individuals that are seeking basic and main facts about Callisto and it's features. It is written out appropriately for anyone to read and is not a challenge to any reader. All the information is on one page and is somewhat easy to find out more. Only to find out more about the surrounding moons of Callisto. And there are no other pages that lead beyond or is external to any other website.

[|PlanetsForKids.org]




 * Date Reviewed:** May 15, 2012
 * Reviewed By:** Adrian Bayaua
 * Date Reviewed:** Dec 07, 2016
 * Reviewed By:** Laura Navarro-Molina

This children's website contains key details and information about Callisto that is appropriate for children K-5. It's very appealing to the eye and with the bright colors makes it nice and decorated for the kids. The page mentions that Callisto has other moons that surround it and is one of the largest moons of Jupiter. There is information explaining the surface of Callisto and it's surface age. It also explains the orbital period around Jupiter. The reading is short and sweet to give enough information, but not overwhelm the kids.

The main facts are very accurate. It seems to explain Callisto's main features very well. The details on the page are up to date. The information on the page is also very reliable. The audience are mostly suitable for children K-5, but anyone else of any age can also take in information from the page as well. The page is written very appropriately for the children providing very simple and basic explanations of Callisto and it's features. The page is also extremely easy to read. It is very easy to find out more information about Callisto. On the page there are highlighted words that are links you can click on to find out more about the meaning of a certain key word that you are unfamiliar of. There are links that lead out of the page but keeps you at the same website.

[|solarviews.com]




 * Date Reviewed:** Dec 07, 2016
 * Reviewed By:** Laura Navarro-Molina

This close up of Callisto shows the heavily cratered surface and the prominent ring structure known as [|Valhalla]. It was acquired by [|Voyager 1] on March 6, 1979. Valhalla's bright central area is about 300 kilometers across with sets of concentric ridges extending out to 1,500 kilometers from the center.

This website is pretty neat they have a quote for each planet, moon, star that they feel is related to the planet. The quote for Callisto is "//Man's mind and spirit grow with the space in which they are allowed to operate". - Krafft A. Ehricke.//

They also show you a little clip of Callisto rotating that allows you to see the different colors it has, the different patters it shows, and you can get an idea of the texture. [|Callisto rotating clip]

There is so much information on this site. You can probably find the answer to whatever you are looking for, but the catch is that you actually have to read it. This site doesn't give you the search button option, so it makes it a little difficult to find it something fast, but if you are looking for answers it's worth the read.

[|Nasa.gov]




 * Date Reviewed:** Dec 07, 2016
 * Reviewed By:** Laura Navarro-Molina

Scientists may have discovered a salty ocean and some ingredients for life on Jupiter's moon October 23, 1998: Until now most scientists thought Jupiter's moon Callisto was a dead and boring moon, an unchanging piece of rock and ice. Data reported in today's issue of Nature could change all that. It appears that Callisto, like another of Jupiter's moons Europa, may have an underground liquid ocean and at least some of the basic ingredients for life.

The most distant of Jupiter's Galilean Moons, Callisto shows the highest density of impact craters in the Solar System, but harbors no volcanoes or even any large mountains. It is thought that the surface is billions of years old. The first hint that something interesting might be happening beneath the surface came from Galileo's measurements of Callisto's magnetic field. Dr. Krishan K. Khurana of UCLA and colleagues discovered that the magnetic field fluctuated in time with Jupiter's rotation. The best explanation was that Jupiter's powerful magnetic field was creating electrical currents somewhere within Callisto, and those currents in turn created a fluctuating magnetic field around Callisto. The image shown above of Jupiter's moon Callisto was captured earlier this year by NASA's Galileo spacecraft. Callisto is approximately the size of the planet Mercury, making it the third largest moon in the Solar System, after Ganymede and Titan. Its icy surface is billions of years old, lacks any sign of volcanic activity, and is densely covered with rifts and craters. Scientists studying data gathered by the Galileo spacecraft now believe that Callisto's heavily cratered surface may overlie a salty liquid ocean. But where could currents flow on Callisto? The icy surface is a poor conductor and the atmosphere is negligible. Dr. Kivelson suggests that "there very well could be a layer of melted ice underneath [the surface]. If this liquid were salty like Earth's oceans, it could carry sufficient electrical currents to produce the magnetic field."

Lending further credence to the premise of a subsurface ocean on Callisto, Galileo data showed that electrical currents were flowing in opposite directions at different times. "This is a key signature consistent with the idea of a salty ocean," Khurana added, "because it shows that Callisto's response, like Europa's, is synchronized with the effects of Jupiter's rotation."