SAN FRANCISCO—In two closely related presentations today at the annual American Geophysical Union conference, Caltech geophysicist Don Anderson will describe work suggesting a radical new interpretation of how Earth operates inside. The work is based on recently declassified satellite imagery as well as a revisiting of the issue of primordial helium (the 3He isotope) within Earth.

Submitted by Dean Bessette, Huntington Beach, Calif., and answered by Dave Stevenson, George Van Osdol Professor of Planetary Science, California Institute of Technology

As everyone with a refrigerator knows, ice cubes tend to shrink over time. And if you have an old-style refrigerator, you may have observed that the ice molecules go directly from the ice cubes to the walls of the freezer compartment without ever becoming liquid water. This is the process of sublimation, and your question about its relevance to the water found on the moon is a good one.

PASADENA— Researchers have singled out a brain enzyme that seems to be essential in memory retention and learning.

Question of the Week: How Do We Know That a Rock Found In The Ice In Antarctica Came From Mars? December 1996 96

Question of the Month: We Hear of Humans Going to Distant Planets in the Future. But if Some Planets Are Light-years Away, How Could An Astronaut Live Long Enough To Get There? November 1996 96

PASADENA— New research from the California Institute of Technology shows that it literally takes some time to smell the roses.

In the current issue of Nature, Caltech neuroscientists Michael Wehr and Gilles Laurent present work demonstrating that information about odors is contained in the temporal activity patterns of groups of neurons over an interval of time.

Tucson, Arizona — When Galileo discovered Ganymede four centuries ago, little did he suspect that the third satellite from Jupiter might be glazed over with the very substance he was breathing.

It took modern astronomical instruments and chemical knowledge for scientists to detect the oxygen and ozone that coat Ganymede. Now, two planetary scientists affiliated with the California Institute of Technology have developed a theory to account for the presence of the substances, as well as the mechanism by which their concentrations are maintained.

PASADENA— Caltech seismologist Kate Hutton has some data that shows where the October 3 meteor may have landed. She's providing the information publicly to help anyone and everyone who wants to try for the $5,000 reward UCLA is offering.

PASADENA— The Galileo probe that dropped into Jupiter's atmosphere last December detected a surprisingly small amount of water. But scientists at the California Institute of Technology have new thundercloud photographs and a theory to suggest that the solar system's largest planet may be "wet" after all.

PASADENA— Biologists have identified a gene that determines whether a given cell in a human or animal embryo will become a neuron rather than some other kind of cell.