One of the great astronomical questions of the age has been Why is Mars so Small? If she developed in a part of the solar system that was richer in loose material than Earth’s, how come she’s smaller? Jupiter, the solar system’s Destroyer, is the answer.
Astronomers and planetologists from a variety of nations have put together a new model of the early solar system that answers, along with the Mars dilemma, a number of questions about how we got here. That new model centers on Jupiter, the solar systems’ bully, as the great destroyer of Mars.
Imagine a time when the bright sun we know as Sol was forming in the middle of a great cloud of loose gas and dust. This cloud, literally billions of miles wide, eddies and clumps and bunches together as it’s sucked towards the strong gravitational forces emanating from the newly forming star.
Within the cloud are vast collections of loose rock, voids -clear spaces without gas, and vast, billowing sheets of loose hydrogen, helium, and methane. And, within this cloud, there are also rocky bodies forming up as rocks and dust clang together under the immense in-drawing breath of the star.
A large body, clumped together from compressed hydrogen and helium, comes streaming in from 300 million miles out, captured in a gas lane that is pouring directly into the newly forming star. Even as its own gravity grows and sucks up the hydrogen in the gas lane this newly forming planet, Jupiter, is on a death march, headed directly for the sun. Jupiter is pulled backwards slightly by the nearby Saturn, but the two of them are no match for the sun, and are both on their way towards a fiery death.
Jupiter follows this gas lane all the way in to 140 million miles, about where Mars will someday soon be forming from a band of loose rock. There the gas lane runs out -the eddy that had captured Jupiter has gone dry, and the sun’s death grip on Jupiter is released.
Saturn’s pull, however, hasn’t released, and Jupiter and Saturn interact on one another, pushing and pulling, until Jupiter is flung out to roughly her present position today. Saturn slips around Jupiter and finds herself parked even farther away from the newborn sun.
But Jupiter’s untimely and massive presence in Mars’ orbit disrupted that planet’s accretion, throwing off in the asteroid belt the matter she was to use to build herself into a planet at least as large as Earth. Jupiter squandered the rocky material in the Mars orbit, denying Mars the chance to develop into what could have been a life-sustaining, vital world.
This is the vision for the early solar system described in the newest model proposed by astronomers at NASA’s Goddard Flight Center. It goes a long way toward explaining the structure and nature of the asteroid belt, the size of Mars, and the distribution of matter beyond Earth’s orbit.
You can learn more about this dramatic interpretation of the early days of the solar system at NASA’s News site.