MATHEMATICAL FORMULA FOR THE FINDING OF RELATIVE DISTANCES OF ORBITS OF PLANETS AND SATELLITES. GENERALIZATION OF THE LAW OF TITIUS-BODE Polychronis Karagkiozidis M.Sc. Chemist – Amateur Astronomer A study of the distances of various large satellites from their parent planets showed that these are subject to the same remarkable harmony that applies to the distances of most of the planets from the sun. I came to this conclusion while searching for this harmony for the solar system’s major satellites. I decided to include in each case an extremely small satellite as the first member of the series, since in the Titius-Bode law the first planet, Mercury, is very small in comparison with the gas giants. For five satellites of Jupiter, including the four Galilean moons: Take the geometrical series 21 42 84 168, in which each term is double the previous one. With the addition of 0 as the first term, we have the series 0 21 42 84 168. Adding 22 to each term produces a third series: 22 43 64 106 190. If we multiply these terms by 10,000, we arrive at the distances in kilometers of Jupiter’s four Galilean moons and the small satellite Thebe from the planet’s centre. 220,000 Thebe 430,000 Io 640,000 Europa 1,060,000 Ganymede 1,900,000 Callisto For five satellites of Uranus: Take the series 46 92 184 368, in which each term is double the previous one. With the addition of 0 as the first term, we have the series 0 46 92 184 368. Adding 86 to each term produces a third series: 86 132 178 270 454. If we multiply these numbers by 1,000, we arrive at the distances in kilometers of the following five satellites from the centre of Uranus: 86,000 Puck 132,000 Miranda 178,000 Ariel 270,000 Umbriel 454,000 Titania The above appear to be an adaptation of the well-known Titius-Bode law to these satellites. This is achieved by identifying the suitable small satellite whose position defines the two constants of the formula that will be given below. The Titius-Bode law is as follows: Take the geometrical series 3 6 12 24 48 96 192, in which each term is double the previous one. With the addition of 0 as the first term, we have the series 0 3 6 12 24 48 96 192. Adding 4 to each term produces a third series: 4 7 10 16 28 52 100 196. If we divide these numbers by 10, we arrive at the distances of most of the planets from the Sun as expressed in astronomical units. 0.4 Mercury 0.7 Venus 1.0 Earth 1.6 Mars 2.8 Ceres 5.2 Jupiter 10.0 Saturn 19.6 Uranus The general formula giving the distances of planets and satellites, which I first presented at the Fourth Panhellenic Amateur Astronomy Conference, is the following: D=λ2n +κ (formula 1) Polychronis Karagkiozidis 1 For a planet’s satellite system, κ corresponds to the (orbit of the) first satellite’s distance from the planet’s centre, and λ to the distance between the second satellite and the first, while n is the number of the satellite in the series, beginning with 0. Similarly for the solar system, κ corresponds to the distance of the first planet, Mercury, from the Sun, and λ to the distance between the second and first planets orbits (Venus − Mercury), while n is the number of the planet in the series, beginning with −∞. For the above Jovian satellites we have: κ=220,000 km (Thebe) and λ=210,000 km (Thebe − Io distance), which give: D=210,000x2n+220,000 (equation 1) Satellite Io Europa Ganymede Callisto n 0 1 2 3 D (km) 430,000 640,000 1,060,000 1,900,000 True distance (km) 421,600 670,900 1,070,000 1,883,000 Deviation % -1.99 4.61 0.93 -0.90 For the above satellites of Uranus we have : Κ=86,000 km (Puck) and λ=46,000 km (Puck − Miranda distance), which give: D=46,000x2n+86,000 (equation 2) Satellite Miranda Ariel Umbriel Titania n 0 1 2 3 D (km) 132,000 178,000 270,000 454,000 True distance (km) 129,780 191,240 265,970 435,840 Deviation % -1.71 6.92 -1.52 4.17 For the solar system we have: κ=0.4 AU (Mercury’s distance from the Sun) and λ=0.3 AU (Mercury − Venus distance’s orbit), which give: D=0.3x2n+0.4 (equation 3) Planet Venus Earth Mars Ceres Jupiter Saturn Uranus n 0 1 2 3 4 5 6 D (AU) 0.7 1 1.6 2.8 5.2 10 19.6 True distance (AU) 0.72 1 1.52 2.76 5.2 9.6 19.2 Deviation % 2.87 0.00 -5.26 -1.45 0.00 -4.17 -2.08 Ceres is the largest of the asteroids or minor planets, which orbit between Mars and Jupiter. REFERENCES Many authors and researchers have studied the Titius-Bode law. An indication of this is that up to April 2005 on the Google search engine there were 9,200 references to this law. In many of these the law is given as d=0.4+0.3x2n (like equation 3 in the present work), from which for n= −∞,0,1,2,3,… we derive the planets’ distances from the Sun in astronomical units. Here we should note that the interval from −∞ to 0 is infinite, and the harmony only exists from 0 onwards, as from that point onward the difference is always one unit. 2 Concerning the satellites of giant planets, different rules are mentioned for each case, as on the site http://floridastars.org/9605cohe.html, which mentions the following: Take the series 1 2 3 8 and add 1 to create a new series 2 3 5 9. If we divide these numbers by 2 we obtain the numbers 1, 1.5, 2.5 and 4.5, which correspond to the relative distances of the four Galilean moons from Jupiter. For the larger satellites of Uranus, the same site gives the rule: Take the series 1 2 3 6 8 and add 1 to create a new series 2 3 4 7 9. If we divide these numbers by 2 we obtain the numbers 1, 1.5, 2, 3.5 and 4.5, which correspond to the relative distances of the four large Uranian satellites from their parent planet. CONCLUSION – ADVANTAGE OF THE FORMULA D=λ2n+κ What is new about the present work is that the formula D=0.3x2n+0.4 is generalised by introducing two factors in place of the constants 0.3 and 0.4. As a result the formula covers not only the solar system but also five Jovian satellites, including the four Galilean moons, and five satellites of Uranus. At first glance this formula appears to fit the Solar System less well than the classic Titius-Bode law, as it does not include Mercury. The Sun − Mercury distance is, however, included in the formula as the constant κ. REFERENCES 1. Κωνσταντίνου Μαυρομάτη, Λεξικό Αστρονομίας, Εκδώσεις «Ώρες» Βόλος 2001. (Νόμος Bode Titius σελ271) 2. Κωνσταντίνου Γαβρίλη, Μαργαρίτας Μεταξά, Παναγιώτη Νιάρχου και Κωνσταντίνου Παπαμηχάλη. Στοιχεία Αστρονομίας και Διαστημικής. Σχολικό βιβλίο Β’ Λυκείου 1999. (αποστάσεις δορυφόρων σελ. 62 63) 3. Πρακτικά 4ου Πανελληνίου Συνεδρίου Ερασιτεχνικής Αστρονομίας. (σελ 57-62) 4. Ian Ridpath, Dictionary of Astronomy, New York, Oxford University Press, 1997. From the internet 5. http://www.daviddarling.info/encyclopedia/T/Titius-Bode_Law.html 6. http://www.anaconda-2.net/g_m/L001.html 7. http://steph.mathis.free.fr/curtitius.html 8. http://www.yorku.ca/sasit/sts/nats1800/lecture11a.html 9. http://www.mira.org/fts0/planets/091/text/txt001x.htm 10. http://almaak.tripod.com/temas/titius_bode_law.htm 11. http://encyclopedia.lockergnome.com/s/b/Titius-Bode_law 12. http://www.floridastars.org/9605cohe.html Polychronis Karagkiozidis M.Sc. Chemist Address: Akropoleos 49 54634 Thessalonica Greece E- mail: info@polkarag.gr 3