January 29, 2018 | David F. Coppedge

Our Solar System Appears Odd to Astronomers *

Our solar system is an oddball, conclude astronomers who looked at hundreds of planetary systems around other stars.

At Space.com, Elizabeth Howell writes, “Earth Resides in Oddball Solar System, Alien Worlds Show.” Why would she say such a thing? Secular scientists have long considered our solar system rather ordinary. Carl Sagan famously demoted the earth’s importance, saying our planet is a tiny speck orbiting a “humdrum star, lost in a galaxy, tucked away in some forgotten corner of a universe in which there are far more galaxies than people.” Perhaps Earth gains a few more points now for being an oddball, but what have astronomers found to change Sagan’s forlorn description?

For one thing, the spacing of planets in our solar system is odd. Most planetary systems identified by the Kepler Space Telescope are equally spaced and have similar sizes, “like peas in a pod,” remarks Lauren Weiss from the University of Montreal. That pattern is clearly not the case here:

By contrast, our own solar system has a range of planetary sizes and distances between neighbors. The smallest planet, Mercury, is about one-third the size of Earth — and the biggest planet, Jupiter, is roughly 11 times the diameter of Earth. There also are very different spacings between individual planets, particularly the inner planets.

Weiss’s team studied 909 planets orbiting 355 stars. They found that small planets tended to have small neighbors, and big planets tended to have big neighbors. Their orbits going out from the star were also regularly spaced. That seems to fit theory, where astronomers believe planets accrete from a dust disk. (Actually, before the Kepler mission, astronomers thought our arrangement was typical, based on a sample size of one.) Explaining our system as an oddball is going to require some ad hoc speculation.

In our own solar system, however, the story is very different. The four terrestrial planets (Mercury, Venus, Earth and Mars) are very widely spaced apart. The team pointed to evidence from other research that Jupiter and Saturn may have disrupted the structure of the young solar system. While the statement did not specify how, several other research studies have examined the movements of these giant planets and their potential impact on the solar system.

Whenever you have to invoke oddball conditions to explain something in science, you run into charges of special pleading. But even if they can model the differences here, the result of this study could mean that an oddball solar system is required for habitable planets. That, in turn, could mean that life is rare in the universe.

Dust Disks Can Be Planet-Free

A dust disk could be an empty nest. Astronomers have long looked at them around other stars and envisioned planets hatching like chicks out of the dust. Gaps seen in the dust disks seemed to clinch the idea that planets were forming, clearing out room for the newborn planets. At Astrobiology Magazine, however, we learn, “No Planets Needed: NASA Study Shows Disk Patterns Can Self-Generate.” Time to change the assumptions:

When scientists searching for exoplanets — worlds located beyond our solar system — first spotted patterns in disks of dust and gas around young stars, they thought newly formed planets might be the cause. But a recent NASA study cautions that there may be another explanation — one that doesn’t involve planets at all.

Model simulations, shown in an embedded video, reveal that the disks can self-generate spirals, rings and arcs that do not necessarily have anything to do with planet formation. They arise from interactions between dust, gas and starlight that can explain the observations that were interpreted as planets.

Earth Is an Oddball in an Odd Solar System

In other planetary news, we learn that those global dust storms that cover the planet Mars every few years. also contribute to the loss of its atmosphere. Elizabeth Howell at Space.com relays news from the Mars Reconnaissance Orbiter that the dust storms “play a key role in promoting gas escape” from the red planet. Measurements show the storms also extract water from the already-dry landscape. “Water vapor is carried up with the same air mass rising with the dust.” Needless to say, without an atmosphere and water, chances for life are slim to none. But too much can be deadly, too: look at Venus, which has crushing pressures, deadly heat, and no astronomy because of its thick cloud layer. These are just some of the things that are making scientists come around to the belief that our planet is very special. Earth is right in the Goldilocks zone in a Goldilocks solar system around a Goldilocks star in a Goldilocks galaxy in a Goldilocks universe.

Read the amazing ‘coincidences’ on Earth that make life possible in Henry Richter’s latest book, Spacecraft Earth: A Guide for Passengers. Everything in the book will underscore just how incredibly special our universe, our solar system, our planet, and life are. You’ll see that it takes an incredible amount of faith to be an atheist these days!

 

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