Johann Daniel Titius was an 18th century German astronomer who first noticed an unusual order to the interplanetary distances between the then known planets (planet discovery had not advanced much since Galileo and astronomers had become obsessed with comets). As early as 1766, Titius had observed that a simple mathematical formulation predicted the planets' relative distances from the Sun. He even predicted that a small planet would be discovered at 2.8 au where there was no known planet.
Johann Elert Bode, head of the Berlin Observatory, latched onto Titius's idea and, without crediting Titius, published them. The law become known as the Titius-Bode law. Here's table showing the actual relative distances of the planets from the Sun and values predicted by the Titius-Bode Law:
Relative Distance From Sun in au
Planet Actual T-B Theory
______________________________________
Mercury 0.39 0.4
Venus 0.72 0.7
Earth 1.0 1.0
Mars 1.52 1.6
-- 2.8
Jupiter 5.2 5.2
Saturn 9.54 10.0
Except for the lack of a planet at 2.8 au, the fit between theory and actual distances is remarkable. I'm fairly certain that Galileo would have embraced Titius-Bode law too, insofar as it was consistent with empirical data at the time.
Two things happened that catapulted Bode to stardom: first, the planet Uranus was discovered by Herschel in 1781. Uranus is beyond Saturn, but is exactly where the law predicted the next further out planet should be. This exciting discovery (Bode was allowed to name the new planet) led to an all out search to find the "missing" planet at 2.8 au. In the words of Titius:
From Mars there follows a space of 4 + 24 = 28 such parts, but so far no planet was sighted there. But should the Lord Architect have left that space empty?The search was on. The heavens were divided into observable sectors among the international community of astronomers. Then, in 1801, the Sicilian astronomer Giuseppe Piazze found Ceres, the dwarf planet and largest asteroid in the asteroid belt. The calculated orbit of Ceres put it between Mars and Jupiter at a distance of 2.77 au in astonishing agreement with the Titius-Bode prediction of 2.8 au. Ceres is considered to be the largest chunk of a planet miscarriage. i.e, material which failed to accrete into a fully-formed planet. The new data is shown below in bold. These two discoveries amounted to both an extrapolation and an interpolation of the Titius-Bode law:
Relative Distance From Sun in au
Planet Actual T-B Theory
__________________________________
Ceres 2.77 2.8
Jupiter 5.2 5.2
Saturn 10.0 9.54
Uranus 19.2 19.6
Few things are as satisfying to a scientist as predicting something which is later backed by experimental data. The Titius-Bode law was accepted as unexplained fact for a half century. Its undoing began in 1846 with the discovery of Neptune at a relative distance of 30.06 au ~ well inside the predicted 38.9 au. The discovery of Pluto in 1930 did not bode well for the law either. Pluto was found well out there at 77.2 au versus a predicted orbit of 39.44 au.
Relative Distance From Sun in au
Planet Actual T-B Theory
______________________________________
Uranus 19.2 19.6
Neptune 30.06 38.8
Pluto 77.2 39.44
I know, I know -- eccentric Pluto was downgraded from planetary status in 2006 and deemed extrasolar in origin and so shouldn't count. But that still leaves Ol' Neptune.
Today, Titius-Bode "theory" is regarded as a historical curiosity.
8 comments:
There is something odd about Neptune: the way its rotational axis is so skewed relative to the other planets.
\o/ Glad to see you.
But whattabout, but whattabout, but whattabout Eris?
Internet is confusing the h-e-double heck sticks outta me.
And I had a crossword clue, giant dwarf planet beyond Pluto and the answer was Eris.
And that right there is oxymoronic.
And looking for that Internet says there are 2 more planets beyond Pluto
And it also say Eris is Pluto's twin
And it also says all this is balderdash, poppycock, folderol, gimcrackery, frippery, flummery and applesauce.
So with all this conflicting dispute, what's a guy to do?
"Giant dwarf planet" sounds a bit oxy-moronic, n'est-ce pas?
Can we still use the word "dwarf" in the 21st century? I'd think "volume challenged" would be more polite.
Dwarf is so sizist.
Welcome back to the table of Levity, chickelit! Where periodic appearances (and disappearances) along with elemental ponderings are part of the grist, gris and grits being served.
Guard your wattle with your life, however, if you aren't into pictures of your caruncle sans feathers being exposed to the world as a gesture of welcome! Be aware that snoods, dewlaps and earlobes also fall into that fleshy category if you're looking to keep your dignity under you hat.
Is there a current theory about the asteroid belt being a destroyed planet?
Not destroyed, but rather never formed.
Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to accrete into a planet.[7][8] Collisions became too violent, and instead of fusing together, the planetesimals and most of the protoplanets shattered. link
Well, that does make sense, thanks.
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