After First Contact, when humans first began to work with Vulcans, we were able to make huge leaps in knowledge by accessing the vast amount of data the Vulcans had already accumulated about the universe (at least, to the extent they would share with us). Part of this knowledge base was information on worlds circling other stars. Being who they are, the Vulcans categorized everything into a logical classification scheme.

In the 21st century we have found life in some bizarre and hostile places on our own planet — deep ocean thermal vents, inside nuclear reactors, and even in mining slag piles where bacteria breathe metal. The more benign conditions we humanoids require are representative of so-called "M-class" or, to use Vulcan terminology, "Minshara-class" planets.

As of today, we now know of 90 planets — so called "extrasolar planets" — circling other stars. None of them are M-class. To date they have been mostly so-called "hot Jupiters," planets several times the size of Jupiter that orbit their parent star at very close distances. These were the first worlds we found because the process of detecting planets finds this sort of system most easily. The smaller the planets, and the further out from their parent star they orbit, the more observation and careful attention to measurement is required.

Yesterday the famed planet-hunting team of Geoff Marcy and Paul Butler announced the discovery of a solar system very much like our own. The star is 55 Cancri — a star very much like our sun located 41 light-years away in the constellation Cancer. If you know where to look you can see this star without a telescope. Marcy and Butler had already found a planet slightly smaller than Jupiter orbiting this star every 14.6 days at a distance one-tenth that of Earth's orbit around our sun.

This latest discovery reveals another Jupiter-sized world orbiting this same star at a distance of 512 million miles — slightly further out than Jupiter's orbit around our own sun. The orbit is slightly more elongated than Jupiter's and it takes 13 years for the planet to complete one orbit (Jupiter does this in 11.86 years). During the press conference, Paul Butler referred to the 55 Cancri system as being "a first cousin of our own".

Why is this so important? Current theory suggests that having a Jupiter-sized planet in an orbit like Jupiter's may be good for the chance of life developing on an "M-Class" planet located where ours is in relation to its parent star. During the formation of a solar system there is a lot of debris such as comets flying around. Jupiter (and to a lesser extent Saturn) serves to deflect comets away from the inner solar system, thus sparing our planet from a constant pummeling of the sort that presumably wiped out the dinosaurs. Without this "celestial vacuum cleaner," the chances that a planet would be suitable for life's origin — to say nothing of being able to support the development of intelligence — would be rather low.

One of the astronomers working with Marcy and Butler did some calculations on the 55 Cancri system. Although no one has seen it, the calculations show that there is a zone in this solar system's inner regions where an Earth-like planet could keep a stable orbit similar to our own for billions of years. Indeed, given the close proximity of this solar system to our own, it is likely that it will be among the first to be examined later this decade by the Terrestrial Planet Finder, a space-based telescope specifically designed to detect Earth-sized worlds around other stars.

In addition to the announcement made about 55 Cancri, Marcy and Butler's team announced a total of 13 new extrasolar planets. Among these is the smallest planet yet detected. The planet orbits the star HD49674 located in the constellation Auriga at a distance of 0.05 AU — that's just one-twentieth the distance from the Earth to our sun. The planet is only 15% the mass of Jupiter, or 40 times the mass of Earth.

While the smallest planets will be the hardest to find, we're getting closer every day. Perhaps when we eventually swap data with the Vulcans we'll have some Minshara-class planets of our own to add to their collection.

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