Giant planets, they surmised, would guzzle gas in a similar way as they grow.
The pictures transmitted by the Voyagers showed the two giant planets, and their assorted moons and rings, in unprecedented detail.
"First, this icy 'super-Earth' dominates the region around its star that in our Solar System is populated by the gas-giant planets, Jupiter and Saturn, " he said.
BBC: NEWS | Science/Nature | Planet hunters find 'super-Earth'
Dr. THOMMES: Well, the violent one, which we think is the more common version, is - you basically have sort of a rapid succession of giant planets forming.
Several panel members have favored dividing planets into categories: terrestrial planets (Mercury, Venus, Earth, Mars), giant planets (Jupiter, Saturn, Uranus, Neptune) and a third class that would include Pluto.
It's possible that the smaller giant planets - Uranus and Neptune, these guys are usually called ice giants rather than gas giants - they may have had some violence in their history.
This would make sense if short-period comets started off in the Kuiper belt and were nudged into closer orbits around the sun by the gravity of the most distant of the giant planets, Neptune.
Just over 50 extrasolar planetary systems have so far been discovered and analysis of them shows just how unusual our local system is with its giant planets (Jupiter and Saturn) positioned well away from the Sun.
In a lot of ways, the weather of the four giant planets (Jupiter, Saturn, Uranus and Neptune) should be easier to understand than that of the earth, because there are no oceans and continents to complicate matters.
But at the same time, what we started to understand about the formation process, we thought there would indeed be a lot of these orbits of giant planets spiraling inward after they're born and things that give you, for instance, hot Jupiters.
Dr. THOMMES: We had have ordered a few percent of systems that where the giant planets at least resemble the architecture in our own system, as to whether we would then have terrestrial planets in the habitable zone, the chances of that actually aren't too bad, because the terrestrial planets, we think, they kind of sprout like mushrooms pretty much anywhere.
This book, which describes the descendants of a civilisation that has converted the material in its planets into a giant ringlike structure around its sun, was inspired by Freeman Dyson's idea that a truly technologically advanced species would endeavour to capture as much light as possible by building a spherical shell around its central star.
ECONOMIST: Is it time for a new approach to finding extraterrestrials?
Astronomers who have been observing the star since 2005 have determined that as the star expanded into the red giant phase, it destroyed one of its own planets.
FORBES: Astronomers Discover A Star That May Have Destroyed Its Own Planet
On the plus side, the ability to directly detect light from a planet closer to the size of Earth than a Jupiter-sized gas giant is a positive step forward in our ability to learn more about planets that might be habitable.
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