Astronomers are calling for Pluto to be re-classified as a planet, and for more celestial bodies to be recognised as so, following the conclusion of a five-year study.

The push comes more than 10 years after Pluto was controversially demoted to a "dwarf planet" in 2006 by the International Astronomical Union (IAU).

But now in a paper to be published in the journal Icarus, a team of astronomers from around the world argue the IAU conflated science with the pseudoscience of astrology.

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Instead they said a planet should be classified according to scientists' 16th century definition; a planet is any geologically active body in space.

By doing so it would expand the number of planets in the solar system

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"We think there's probably over 150 planets in our solar system," said lead-author, and planetary physicist at the University of Central Florida, Philip Metzger.

"We are continuing to call Pluto a planet in our papers, we are continuing to call Titan and Triton and some other moons by the term 'planet'.

"Basically, we are ignoring the IAU."

Pluto — the solar's system's ninth planet since 1930 — was re-classifed as the IAU changed the definition of what makes a planet.

The organisation deemed a planet needs to be spherical, orbit the sun and needs to have cleared its orbit of other objects.

This last point is what nixed Pluto from the list.