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Thanks to a continent-wide radio telescope, astronomers say they know where Saturn is - to within one mile, the BBC reported.

The calculation is many times more accurate than previous estimations and will be useful for the future study of our solar system and beyond.

It used signals sent by the spacecraft Cassini, orbiting Saturn since 2004.

Ten antennae scattered from Hawaii to the Virgin Islands performed the precise measurement, despite Saturn being nearly a billion miles away.

This powerful assembly is known as the Very Long Baseline Array (VLBA), a giant telescope in ten parts.

The findings were reported at a meeting of the American Astronomical Society in Seattle.

"Because of [the VLBA's] large geographic extent, it has the ability to make very high resolution images - but for this study, the critical thing it can do is measure very precise angles," explained Dr Dayton Jones of Nasa's Jet Propulsion Laboratory.

Dr Jones and his colleagues tracked Cassini's position relative to a reference grid of quasars - bright, ancient radio wave sources well beyond our galaxy.

Without using this type of radio astronomy, where the antennae compare notes in a technique known as "interferometry", Dr Jones said the best estimates of Saturn's location were about 20 times less precise.

From our distant vantage point, predicting Saturn's trajectory to within about one mile is the equivalent of "the width of a dime at 2,000 miles", Dr Jones said.

"This is very good, and far better than previous techniques have been able to provide," he added, commending the "extraordinary precision" of the VLBA.

And that precision is especially important when it concerns a giant planet like Saturn.

"Getting better orbits... particularly for the two planets that dominate the dynamics of our solar system, Jupiter and Saturn, improves the basis of the entire ephemeris," Dr Jones said.