Did Galileo Discover Neptune?

Most everybody knows about Galileo Galilei (1564-1642), the great Italian scientist who was the first to make astronomical observations using a telescope and deemed a heretic by the Church for supporting the Copernican or Sun-centered theory of the solar system.

But did you know that Galileo also may have been the first man to observe and record the planet Neptune?

Neptune, the eighth planet from the Sun, was not officially discovered until 1846, after its existence was predicted more or less simultaneously by two different mathematicians trying to account for unknown gravitational influences upon the planet Uranus (which is in turn seventh in line from the Sun and was actually not known until 1781, when it was found by the great English astronomer and telescope maker, Sir William Herschel).   

But according to this MSNBC article, Galileo saw Neptune in 1613. 

Scholars have apparently been aware for some time that Galileo observed and recorded the planet when it passed very near Jupiter — whose four brightest moons he discovered in 1610 — but they were previously of the opinion “that he discounted the object as a star and gave it no further thought.” 

However, David Jamieson, a physicist with the University of Melbourne who has been studying the famous Italian’s notebooks, says Galileo actually recorded that Neptune moved against the background of stars — something only a relatively nearby object like a planet would do.

I myself have observed Neptune a time or two in a telescope.  Though it only presented the tiniest disk, it is of a remarkable blue color — as the photo above would suggest.

Most of Greensboro Public Library’s books on Neptune are either juveniles (such as Neptune by Dana Meachen Rau) or too dated to be of interest to adult readers. 

But we do have some more recent books on the planets generally which adult readers may find interesting, such as:  Where Did Pluto Go?:  A Beginner’s Guide to Understanding the New Solar System by Paul Sutherland; The New Solar System:  Ice Worlds, Moons, and Planets Redefined by Patricia Daniels; and Is Pluto a Planet?:  A Historical Journey Through the Solar System by David A. Weintraub.  These titles especially take up the recent redefinition of Pluto as a “dwarf” or “minor planet,” which means that Neptune is now considered (once again) to be the outermost planet in the solar system.                

Also, give Science Online a try.  You’ll find some good articles on Neptune in there.


One Response

  1. […] can also check this previous post for some of our more recent general works on the solar system, and you’ll find lots of […]

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