BAA Computing Section

Morsel: Major planets in sequence

Q: Can all of the major planets ever appear strung out from the Sun in the correct order of their orbital radii?

A: The short answer is "yes" because here is an example from a few years ago:

Chart showing all planets in sequence, on 2002 November 6th

That has the bonus that Pluto (now officially a minor planet) is also in sequence. It is nevertheless not a great example because the planets are spread right across the sky. They could not be observed in a single instant. Mercury and Venus are also much too close to the Sun.

So let's refine the question: can all the major planets appear in sequence with a spread of less than 180° and with none of them too close to the Sun?

Yes again but the best example we have managed to find lies 1200 years in the future:

Chart showing all major planets in sequence, on 3211 November 20th

Here all the major planets lie in an ecliptical longitude range of about 130°. The Moon is in a logical place too!

We have searched all days from JD2000000 (763 Sep 14) to JD3000000 (3501 Aug 15) using a Java implementation of the VSOP87 algorithm (planet positions accurate to 1 arcsecond) and obtained the following results. Arrangements for which the spread of longitudes is less than 180° have been highlighted in yellow. The direction column of the table shows whether the sequence is ordered eastwards from the setting Sun or westwards from the rising Sun. Enter the Julian Dates into our "What's observable" applet to see the arrangements plotted.

Direction	Start JD	Start date	End JD	End date	No of days	Min spread (°)
E	2009127	0788-Sep-09	2009153	0788-Oct-05	27	312
W	2017568	0811-Oct-20	2017570	0811-Oct-22	3	343
W	2018156	0813-May-30	2018157	0813-May-31	2	201
W	2018240	0813-Aug-22	2018282	0813-Oct-03	43	290
W	2018938	0815-Jul-21	2018948	0815-Jul-31	11	253
W	2018960	0815-Aug-12	2018976	0815-Aug-28	17	269
W	2032947	0853-Nov-27	2032957	0853-Dec-07	11	298
E	2064632	0940-Aug-27	2064692	0940-Oct-26	61	265
E	2065345	0942-Aug-10	2065397	0942-Oct-01	53	300
W	2074438	0967-Jul-03	2074445	0967-Jul-10	8	267
W	2074480	0967-Aug-14	2074481	0967-Aug-15	2	309
W	2083703	0992-Nov-13	2083716	0992-Nov-26	14	338
W	2084401	0994-Oct-12	2084402	0994-Oct-13	2	309
W	2139821	1146-Jul-06	2139838	1146-Jul-23	18	225
W	2155372	1189-Feb-01	2155373	1189-Feb-02	2	351
E	2189556	1282-Sep-05	2189561	1282-Sep-10	6	345
E	2196564	1301-Nov-12	2196567	1301-Nov-15	4	326
W	2199290	1309-Apr-30	2199292	1309-May-02	3	177
W	2199354	1309-Jul-03	2199397	1309-Aug-15	44	237
W	2205265	1325-Sep-08	2205266	1325-Sep-09	2	269
W	2215634	1354-Jan-28	2215636	1354-Jan-30	3	350
W	2234386	1405-Jun-01	2234386	1405-Jun-01	1	345
E	2241003	1423-Jul-14	2241018	1423-Jul-29	16	329
E	2241738	1425-Jul-18	2241765	1425-Aug-14	28	326
E	2255718	1463-Oct-27	2255738	1463-Nov-16	21	314
W	2266326	1492-Nov-11	2266357	1492-Dec-12	32	321
W	2267074	1494-Nov-29	2267079	1494-Dec-04	6	339
W	2299756	1584-Jun-01	2299756	1584-Jun-01	1	319
E	2312736	1619-Dec-15	2312738	1619-Dec-17	3	286
E	2312780	1620-Jan-28	2312785	1620-Feb-02	6	233
E	2313424	1621-Nov-02	2313483	1621-Dec-31	60	268
E	2313593	1622-Apr-20	2313598	1622-Apr-25	6	157
W	2331718	1671-Dec-04	2331741	1671-Dec-27	24	298
W	2332487	1674-Jan-11	2332500	1674-Jan-24	14	335
W	2335800	1683-Feb-06	2335801	1683-Feb-07	2	349
W	2336475	1684-Dec-12	2336492	1684-Dec-29	18	281
W	2336541	1685-Feb-16	2336545	1685-Feb-20	5	350
W	2350399	1723-Jan-27	2350401	1723-Jan-29	3	250
W	2350469	1723-Apr-07	2350511	1723-May-19	43	293
W	2351182	1725-Mar-20	2351210	1725-Apr-17	29	276
E	2364131	1760-Sep-01	2364132	1760-Sep-02	2	339
E	2364177	1760-Oct-17	2364238	1760-Dec-17	62	227
E	2378142	1799-Jan-11	2378142	1799-Jan-11	1	292
E	2378811	1800-Nov-11	2378841	1800-Dec-11	31	321
E	2378908	1801-Feb-16	2378951	1801-Mar-31	44	215
W	2387190	1823-Oct-21	2387243	1823-Dec-13	54	284
W	2387914	1825-Oct-14	2387932	1825-Nov-01	19	268
W	2387994	1826-Jan-02	2387994	1826-Jan-02	1	358
W	2401200	1862-Feb-28	2401202	1862-Mar-02	3	335
W	2401215	1862-Mar-15	2401222	1862-Mar-22	8	329
W	2401909	1864-Feb-07	2401957	1864-Mar-26	49	291
E	2429531	1939-Sep-24	2429539	1939-Oct-02	9	339
E	2429587	1939-Nov-19	2429597	1939-Nov-29	11	281
E	2444298	1980-Feb-28	2444305	1980-Mar-06	8	271
W	2452584	2002-Nov-05	2452593	2002-Nov-14	10	268
W	2452653	2003-Jan-13	2452671	2003-Jan-31	19	332
W	2453351	2004-Dec-11	2453369	2004-Dec-29	19	297
W	2453386	2005-Jan-15	2453406	2005-Feb-04	21	322
W	2466609	2041-Mar-30	2466615	2041-Apr-05	7	319
E	2507805	2154-Jan-13	2507809	2154-Jan-17	5	341
W	2518817	2184-Mar-08	2518818	2184-Mar-09	2	354
E	2560019	2296-Dec-28	2560022	2296-Dec-31	4	318
E	2573235	2333-Mar-06	2573278	2333-Apr-18	44	286
E	2573942	2335-Feb-11	2573972	2335-Mar-13	31	324
W	2583018	2359-Dec-18	2583025	2359-Dec-25	8	243
W	2583081	2360-Feb-19	2583083	2360-Feb-21	3	312
E	2624680	2474-Jan-10	2624721	2474-Feb-20	42	284
E	2625392	2475-Dec-23	2625410	2476-Jan-10	19	323
W	2647611	2536-Oct-23	2647612	2536-Oct-24	2	163
W	2647677	2536-Dec-28	2647743	2537-Mar-04	67	223
W	2647788	2537-Apr-18	2647806	2537-May-06	19	334
W	2648376	2538-Nov-27	2648436	2539-Jan-26	61	187
W	2648482	2539-Mar-13	2648482	2539-Mar-13	1	303
W	2649990	2543-Apr-29	2650011	2543-May-20	22	332
E	2661408	2574-Aug-02	2661424	2574-Aug-18	17	326
W	2663083	2579-Mar-04	2663083	2579-Mar-04	1	204
E	2675374	2612-Oct-28	2675377	2612-Oct-31	4	352
E	2676120	2614-Nov-13	2676163	2614-Dec-26	44	285
E	2690069	2653-Jan-21	2690079	2653-Jan-31	11	337
E	2694110	2664-Feb-14	2694137	2664-Mar-12	28	327
E	2694905	2666-Apr-19	2694908	2666-Apr-22	4	295
W	2701439	2684-Mar-09	2701458	2684-Mar-28	20	331
W	2713142	2716-Mar-25	2713209	2716-May-31	68	277
W	2713838	2718-Feb-19	2713843	2718-Feb-24	6	241
E	2726821	2753-Sep-06	2726829	2753-Sep-14	9	345
E	2727568	2755-Sep-23	2727594	2755-Oct-19	27	305
E	2760261	2845-Mar-27	2760305	2845-May-10	45	309
E	2761812	2849-Jun-25	2761818	2849-Jul-01	7	269
E	2761869	2849-Aug-21	2761937	2849-Oct-28	69	147
W	2763821	2854-Dec-25	2763849	2855-Jan-22	29	236
W	2763897	2855-Mar-11	2763931	2855-Apr-14	35	317
W	2764594	2857-Feb-05	2764605	2857-Feb-16	12	280
W	2764653	2857-Apr-05	2764663	2857-Apr-15	11	338
W	2767606	2865-May-06	2767606	2865-May-06	1	358
E	2778267	2894-Jul-14	2778275	2894-Jul-22	9	346
W	2778622	2895-Jul-04	2778634	2895-Jul-16	13	343
W	2830064	3036-May-08	2830066	3036-May-10	3	342
W	2845140	3077-Aug-17	2845150	3077-Aug-27	11	344
E	2886734	3191-Jul-05	2886734	3191-Jul-05	1	301
E	2886785	3191-Aug-25	2886814	3191-Sep-23	30	203
W	2894155	3211-Oct-29	2894205	3211-Dec-18	51	118
W	2895799	3216-Apr-29	2895832	3216-Jun-01	34	275
W	2896582	3218-Jun-21	2896593	3218-Jul-02	12	342
E	2942233	3343-Jun-17	2942237	3343-Jun-21	5	286
E	2942897	3345-Apr-11	2942927	3345-May-11	31	326
E	2944559	3349-Oct-29	2944561	3349-Oct-31	3	170
W	2961184	3395-May-06	2961189	3395-May-11	6	268
W	2961244	3395-Jul-05	2961275	3395-Aug-05	32	326
W	2961933	3397-May-24	2961958	3397-Jun-18	26	282
W	2961972	3397-Jul-02	2961992	3397-Jul-22	21	304
E	2993642	3484-Mar-18	2993681	3484-Apr-26	40	287

For Java programmers: the search was easy to write by calling methods in file Holst.jar which we had already written for the "What's observable" applet. Is there any interest in our making the API documentation (Javadoc) available?

British Astronomical Association - Computing Section - britastro.org/computing

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Morsel: Major planets in sequence