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  • Kansas Legislator Proposes Bill to Outlaw Sustainability Education
    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of ...Read more

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    Kansas Legislator Proposes Bill to Outlaw Sustainability Education

    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of sustainability. Here is a link to the one-page bill: http://www.kslegislature.org/li/b2013_14/measures/documents/hb2366_00_0000.pdf. See report on Bloomberg News.
  • Earth's Center Is 1,000 Degrees Hotter Than Previously Thought, Synchrotron X-Ray Experiment Shows
    Scientists have determined the temperature near the Earth’s center to be 6000 degrees Celsius, 1000 ...Read more

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    Earth's Center Is 1,000 Degrees Hotter Than Previously Thought, Synchrotron X-Ray Experiment Shows

    Scientists have determined the temperature near the Earth’s center to be 6000 degrees Celsius, 1000 degrees hotter than in a previous experiment run 20 years ago. These measurements confirm geophysical models that the temperature difference between the solid core and the mantle above, must be at least 1500 degrees to explain why the Earth has a magnetic field. For more information about this study, see the press release from the European Synchrotron Radiation Facility.
  • Ocean Volcanic Rocks Contain Samples of Recycled Crust
    Scientists have long believed that lava erupted from certain oceanic volcanoes contains materials fr...Read more

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    Ocean Volcanic Rocks Contain Samples of Recycled Crust

    Scientists have long believed that lava erupted from certain oceanic volcanoes contains materials from the early Earth’s crust. But decisive evidence for this phenomenon has proven elusive. New research from a team including Carnegie’s Erik Hauri demonstrates that oceanic volcanic rocks contain samples of recycled crust dating back to the Archean era 2.5 billion years ago. Their work is published in Nature. Oceanic crust sinks into the Earth’s mantle at so-called subduction zones, where two plates come together. Much of what happens to the crust during this journey is unknown. Model-dependent studies for how long subducted material can exist in the mantle are uncertain and evidence of very old crust returning to Earth’s surface via upwellings of magma has not been found until now. For more information about these results, see the press release from the Carnegie Institution.
This drawing shows the evolution of Callisto.
Click on image for full size
NASA

Evolution of Callisto

The insides of most of the moons and planets separated while they were forming out of the primitive solar nebula.

Measurements by the Galileo spacecraft have been shown that Callisto is the same inside from the center to the surface, and did not form a core. This means that, unlike Ganymede, Callisto probably never warmed inside enough to allow for the materials to separate. Planets gain heat by many means. The fact that Callisto never warmed could mean one of many things:

  • insufficient warming from forces leading to tides
  • insufficient abundance of radioactive elements

The lack of warmth prevented any movements of the crust which would have changed the appearance of the surface over time.

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Differentiation

Differentiation is a scientific term which really means "to separate". In their earliest history, elements which made the planets would part into separate regions, if the planet were warm enough. This...more

Tidal Forces

The force of gravity caused by an object gets weaker as you move farther away from that object. In this picture, the Earth is pulling on the Moon, and the Moon is pulling on the Earth. The Moon pulls more...more

Surface of Callisto

The surface of Callisto is deeply pockmarked with craters. It looks to be perhaps the most severely cratered body in the solar system. There are also very large craters to be found there. The severity...more

Amalthea

Amalthea was discovered by E Barnard in 1872. Of the 17 moons it is the 3rd closest to Jupiter, with a standoff distance of 181,300 km. Amalthea is about the size of a county or small state, and is just...more

Callisto

Callisto was first discovered by Galileo in 1610, making it one of the Galilean Satellites. Of the 60 moons it is the 8th closest to Jupiter, with a standoff distance of 1,070,000 km. It is the 2nd largest...more

Evolution of Callisto

The insides of most of the moons and planets separated while they were forming out of the primitive solar nebula. Measurements by the Galileo spacecraft have been shown that Callisto is the same inside...more

Very Large Impact Crater

Many examples of the differing types of surface are shown in this image. In the foreground is a huge impact crater, which extends for almost an entire hemisphere on the surface. This crater may be compared...more

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