Recipe for an "instant" Earth-like planet: scrape up cosmic dust swirling around a newborn star and wait a mere three million years.

Even the building blocks for giant gas planets like Jupiter might form just as quickly, about three times faster than many scientists believe, a team of astronomers reported on Monday.

Three million years may sound like a long time when set against the human life span, but it is a relative blink of the eye in cosmic time. Earth is considered a middle-aged planet at about 4.5 billion years or so, and compared to Earth, these theoretical 3-million-year-old planets would be formed when the star they orbit is the equivalent of a 1-week-old baby.

Astronomers Elizabeth Lada of the University of Florida in Gainesville and Karl Haisch of the University of Michigan in Ann Arbor concluded that the beginnings of planets might form about three million years after stars are born by studying the dusty disks that form around the infant stars.

These disks are made of cosmic dust and gas that can either be absorbed into the still-forming star or spun out into clumps of material that can become planets. But without a disk, it is unlikely that planets will form around a star.

The team found that while disks surrounded many star babies as they clustered together in stellar nurseries at about 1 million years of age, there were relatively few by the time the stars were 3 million years old and none by the time they were 6 million years old.

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