Before the discovery of the first exoplanet that orbits a star like ours, 51 Pegasi b, the assumption of solar system scientists was that others planetary systems that might exist were likely to be like ours. Small rocky planets in the inner solar system, big gas giants like Jupiter, Saturn and Neptune beyond and, back then, Pluto bringing up the rear
But 51 Peg b broke every solar system rule imaginable. It was a giant and hot Jupiter-size planet, and it was so close to its star that it orbited in a little over four days. Our Jupiter takes twelve years to complete an orbit.
This was the “everything we knew about solar systems is wrong” period, and twenty years later thinking about the nature and logic of solar system architecture remains very much in flux.
But progress is being made, even if the results are sometimes quite confounding. The umbrella idea is no longer that solar, or planetary, systems are pretty much like ours, but rather that the galaxy is filled with a wild diversity of both planets and planetary systems.
Detecting and trying to understand planetary systems is today an important focus 0f exoplanet study, especially now that the Kepler Space Telescope mission has made clear that multi-planet systems are common.
As of early July, 632 multi planet systems have been detected and 2,841 stars are known to have at least one exoplanets. Many of those stars with a singular planet may well have others yet to be found.
An intriguing newcomer to the diversity story came recently from University of Montreal astronomer Lauren Weiss, who with colleagues expanded on and studied some collected Kepler data.
What she found has been deemed the “peas in a pod” addition to the solar system menagerie.
Weiss was working with the California-Kepler Survey, which included a team of scientists pouring over, elaborating on and looking for patterns in, among other things, solar system architectures.
Weiss is part of the California-Kepler Survey team, which used the Keck Observatory to obtain high-resolution spectra of 1305 stars hosting 2025 transiting planets originally discovered by Kepler.… Read more