A new and powerful computer model shortens the theoretical time it takes to build a giant planet to as little as 300 years. The result could help explain mysteries of our solar system as well as some of the hundred or so planets found around other stars.

Planets larger than gaseous Jupiter and as small as icy Neptune might form in just centuries around a newborn star, the calculations show, compared to the millions of years astronomers once thought.

For a few years now, astronomers have known that their standard model of planet formation wasn't working well. It cannot account for Uranus and Neptune, large frozen planets on the outskirts of our solar system. Nor does it explain huge planets, most larger than Jupiter, that have been detected orbiting very close to other stars.

The standard model holds that a rocky Earth-like core forms first, then objects that are destined to become gas or ice giants begin accumulating material around the rocky core. This process, called core accretion, is thought to take anywhere from one million to eight million years.

But the scenario doesn't explain why Uranus and Neptune don't have massive gaseous envelopes.

The standard model also breaks down once applied to other stars. A planet trying to become a giant in an intense star-formation region would quickly grow impatient. A flood of radiation from nearby massive stars would strip the necessary material away, through a process called photoevaporation, faster than the model says a planet could gather it up. The planet would never develop.

Importantly, most stars are born in these congested areas of star birth, so astronomers suspect that they must account for planet formation in such a place.

To fill these gaps in understanding, theorist Alan Boss at the Carnegie Institution of Washington developed a theory for building planets more quickly. In Boss' disk instability model, the guts of which date back to the 1950s, a planet simply collapses out of a knot of material that develops in the disk of gas and dust leftover from the formation of a star.

Boss figured that the raw material for a Jupiter-like planet could be assembled in about 1,000 years, though more time would be needed for the fluffy collection of stuff to condense down into a planet.

"We could actually follow the fragmentation of these spiral arms into individual planets," said one of Mayer's team members, astrophysicist Thomas Quinn of the University of Washington.

The computer makes gas giants in the size and orbit range of Jupiter in about 300 years, Quinn said in a telephone interview. Outer planets like Neptune take longer, but still less than 1,000 years.

The calculations also support the plausibility of the most controversial aspect of Boss' work, that Uranus and Neptune were stripped of gas in a region of rapid star formation.

Boss told SPACE.com that Mayer and Quinn's work uses a different technique "to confirm the basic credibility of my disk instability models, and to show that the clumps that form may well persist long enough to become giant planets."

The new research, which is detailed in the Nov. 29 issue of the journal Science, also speaks to other worlds. Though some discoveries around other stars involve planets the size of Jupiter and smaller, most are more massive. Theorists must explain how these worlds form.

An important test of any computer model is whether it can predict what ought to occur in Nature.

"We're actually making predictions about planet masses from this model," Quinn said. "They're actually matching up with the size of planets we see around other stars."