The recent launching of the Cassini-Huygens Saturn probe has brought renewed attention to the wonders and mysteries of our solar system. This system consists of a central star or sun surrounded by nine planets rotating in an ecliptic plane. The four closest planets, Mercury, Venus, Earth, and Mars are called terrestrial planets because they resemble Earth in being composed of rock and metal. The four outer planets, Jupiter, Saturn, Uranus, and Neptune, are called Jovian planets because they resemble Jupiter in being composed of gaseous or liquid hydrogen and helium. Pluto is thought to be composed of rock and ice. How these planets evolved so as to be rotating about the sun in the same direction and in the same ecliptic plane is a matter of much speculation. It is generally thought, from infrared astronomical observation of protoplanetary discs, that the planets coalesced from dust rings similar to the rings around Saturn.
Saturn, the sixth planet from the sun, was first observed by Galileo in 1610, but his crude telescope was unable to distinguish the rings. In 1655, using a more powerful telescope, the Dutch astronomer, Christian Huygens, first identified the ring structure, and in 1675 Gian Domenico Cassini observed a gap between the A and B rings now called the Cassini Division in his honor. Now we know that there are thousands of rings extending out 46,000 miles from the planet, and that there are 31 moons of varying sizes and composition. The largest moon, Titan, has a diameter greater than that of the planet Mercury, and the Huygens probe will be dispatched to land on Titan on Christmas Eve, 2004.
The origin of these many rings is a topic of much speculation. Other planets such as Jupiter also have rings, but they are quite faint. It is thought that the rings are the remains of small pulverized moons that were destroyed by cataclysmic meteor impacts or by wandering too close to a gravitational line called the Roche limit. This is the altitude where the unequal gravitational forces on an object is great enough to pull the object apart, but not strong enough to pull it out of orbit. This limit would differ according to the size and mass of the moon, thus resulting in different rings.
Spiritually speaking, we are all caught in a gravitational situation where, due to our sinful natures, we feel a powerful attractive force toward evil. Unless we allow Jesus and His message of salvation to keep us safe, we shall be drawn inexorably by the temptation of the flesh and the devil toward that line of rebellion that will mean certain destruction. This is a line that God has drawn, the line between justice and mercy which we must not cross. Just as an object that crosses the gravitational Roche limit is destroyed, so we may be destroyed by crossing the line of God's justice, which I choose to call "the spiritual Roche limit."
