Image of Jupiter's largest moon, Ganymede
Click on image for full size
Courtesy of NASA
Dust Around Moon Gives Clues to Planetary Rings
News story originally written on June 17, 1999
With the help of Galileo, scientists have discovered new evidence that may explain planetary rings. We already know the rings are made of dust and ice. However, until now scientists only had guesses as to how the rings actually formed.
Galileo has found small grains of dust that are always bombarding celestial bodies. When the high speed particles hit the surface, they throw pieces of debris up into space. Smaller bodies, such as moons, have a gravity just strong enough to hold the particles in orbit. Eventually, the grains form a ring.
The research was conducted while studying Ganymede, the largest of Jupiter's 15 moons. Using a small metal can, scientists could measure the speeds of the meteoroids when they hit the moon.
Unfortunately, this new study fails to shed any light on the formation of Saturn's rings, which are made of big chunks of ice.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, ranging from seismology
, rocks and minerals
, and Earth system science
You might also be interested in:
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 main mission was to explore Jupiter and...more
It was another exciting and frustrating year for the space science program. It seemed that every step forward led to one backwards. Either way, NASA led the way to a great century of discovery. Unfortunately,...more
The Space Shuttle Discovery lifted off from Kennedy Space Center on October 29th at 2:19 p.m. EST. The weather was great as Discovery took 8 1/2 minutes to reach orbit. This was the United States' 123rd...more
A moon was discovered orbiting the asteroid, Eugenia. This is only the second time in history that a satellite has been seen circling an asteroid. A special mirror allowed scientists to find the moon...more
Will Russia ever put the service module for the International Space Station in space? NASA officials want an answer from the Russian government. The necessary service module is currently waiting to be...more
A coronal mass ejection (CME) happened on the Sun early last month. The material that was thrown out from this explosion passed the ACE spacecraft. The SWICS instrument on ACE has produced a new and very...more
J.S. Maini of the Canadian Forest Service called forests the "heart and lungs of the world." This is because forests filter air and water pollution, absorb carbon dioxide, release oxygen, and maintain...more