Astronomer Galileo Galilei may have discovered Neptune in 1613 - 234 years before the planet was officially found, according to a new theory.
Prof David Jamieson of the University of Melbourne has claimed in his theory that the notebooks of Galileo from some 400 years ago contain concrete evidence that he had discovered a new planet in 1613, which is now known as Neptune.
And, according to him, if correct, the discovery would probably be the first new planet, identified by humanity since deep antiquity.
Galileo was observing the moons of Jupiter in 1612 and 1613 and recorded his observations in his notebooks. Over many nights he had also recorded the position of a nearby star that does not appear in any modern star catalogue.
"It has been known for several decades this unknown star was actually planet Neptune. Computer simulations show the precision of his observations revealing that Neptune would have looked just like a faint star almost exactly where Galileo observed it.
"Galileo may indeed have formed the hypothesis that he had seen a new planet which had moved right across the field of view during his observations of Jupiter over the month of January 1613. If this is correct Galileo observed Neptune 234 years before its official discovery," Prof Jamieson said.