Shop Windows to the Universe

The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.
These are drawings of the interior of Io.
Click on image for full size
NASA

Interior of Io

The diagram to the left shows a cutaway of the possible interior structure of Io, based on recent measurements by the Galileo spacecraft. It shows a large iron/sulphur core (the Earth's core is iron/nickel), overlain with a silicate rocky material. There is no ice present within Io.

When the Galileo spacecraft flew by Io it measured the "figure" of Io. The measurements indicated that Io was fully differentiated into two distinct interior layers, as shown in this picture.

The history of Io is one of continuous warming due to tidal forces, which results in extensive volcanism on the surface. The tidal forces cause Io to warm up the same way a coat hanger, folded back and forth will cause coat hanger to warm. As shown in the figure, possible pools of melted, liquid sulphur, encounter the hot pockets of Io's interior and boil, providing Io with geysers on the surface.

With such extensive heating, it is possible that the core may be provided with motions sufficient for a magnetic field.

Shop Windows to the Universe Science Store!

Our online store includes fun classroom activities for you and your students. Issues of NESTA's quarterly journal, The Earth Scientist are also full of classroom activities on different topics in Earth and space science!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Differentiation

Differentiation is a scientific term which really means "to separate". In their earliest history, elements which comprised the planets and moons would part into separate regions, if the body was warm enough....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

Galileo

The Galileo spacecraft was launched on October 19, 1989. Galileo had two parts: an orbiter and a descent probe that parachuted into Jupiter's atmosphere. Galileo's primary mission was to explore the Jovian...more

Galileo Reaches the End of its Road

The Galileo spacecraft, which has been orbiting Jupiter since 1995, has finally reached the end of its road. On September 21, 2003, Galileo will make a fiery plunge into Jupiter's atmosphere and be vaporized....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

Most of the moons and planets formed by accretion of rocky material and volatiles out of the primitive solar nebula and soon thereafter they differentiated. Measurements by the Galileo spacecraft have...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF