Mutual Planetary Occultations Past and Future

Their Observation Circumstances

by Larry Bogan
Cambridge Station, NS


Steven C. Albers has looked into planetary occultation. See his article
Mutual Occultations of Planets: 1557 to 2230
Sky and Telescope March 1979 p 220-222

He wrote a high precision computer program to search for mutual occultations of planets. He found 21 such events in the period from 1557 to 2230 with none in the 20th century and only 2 in the 19th century. What do we have to look forward to in the next century? He lists 5 events but they do not occur until 2065 and after. Incidently, he did find the 1737 Venus-Mercury occultation seen by Bevis. I have added a few more mutual occultations with detail as found by using the software, GUIDE ver 7.0 (Project Pluto).

Of the 21 mutual planetary occultation found by Albers, 9 involved Mercury as the occulting body while and 8 involve Venus. There are two involving both Venus and Mercury, the one in 1737 and another in 2133. Only 4 mutual occultations occur exclusively between the superior planets.

I have divided the events according to planets involved.

The 2133 occultation occurs only 4o from the Sun with Venus near inferior conjunction while Mercury is on the other side of the Sun near superior conjunction. Not a very good situation for good observation.

Venus and Jupiter Occultations

The unusually long gap in mutual occultations during our time spans nearly 250 years from 1818 and the next one is in 2065. Both of these occultations are Jupiter- Venus events and the most spectacular type.

What of the next one in 2065 which a few young people have a chance of seeing? This will be an occultation of Jupiter by Venus but it is only 8o from the Sun and will be essentially unobservable. It surely would have been a beautiful occultation with two bright planets covering each other. Similar occultations occured between these two planets in 1570 and 1818 which surely would have been noticed by observers but no historical records have surfaced yet. There is one more predicted in 2123 and will take place at an elongation of 16o from the Sun.
from the Sun
Venus, Jupiter Diameters
Geocentric Separation
2 BC17 Jun 17:53 UT45oW26",32",28"Very Large Elongation
Occurs over Middle East
121017 Sep 10:35 UT7oW10",31", 0"Too Close to the Sun
Central occultation
15705 Feb 7:47 UT25oW11",31",18"Occurred over South Atlantic, Argentina
No Historic Record
18183 Jan 21:51 UT16oW10",30",12"Occurred over Far East
No History Record
Over Unpopulate Area
206522 Nov 12:47 UT8oW10",29",14"Too Close to the Sun
212314 Sep 15:26 UT16oE10",29", 6"Occurs over the Pacific Ocean

All the other Venus occultations of Jupiter have similar restrictions

Occultations Involving Mercury

After the Jupiter-Venus event in 2065, the next mutual occultations are ones by Mercury. Two years after 2065 Mercury covers the 7th magnitude Neptune; but it is not central and the occultation is visible only in in the far north, where the Sun is up all day in July. After that, you would have to live until 2079 to see Mercury occult Mars 11o from the Sun in the sky. (Map of visiblity, 2079) The Occultation will last only 2-1/2 minutes and observable only near East longitude 50o before Sun rise in the morning. A likely place would be on the western shores of the Caspian sea in Georgia or maybe farther south in Iran.

2079 ocultation of Mars by Mercury
Beginning of the occultation of Mars by Mercury in 2079, August 11, 1:26 UT

YearOther PlanetDate
UT time
from the Sun
Mercury and
Planet Size
and Separation
1708Uranus14 Jul 13:03 UT25oE6", 4", 8"Uranus Not Discovered Yet
1708Jupiter4 Oct 12:46 UT1oE5", 28", 11"Too Near the Sun
1737Venus28 May 21:5022oE 7", 52", 35"Observed By Bevis
Only historical detailed account
1793Uranus21 Jul 5:40 UT24oE6", 4", 1"Uranus Discovered 1781
Only Observable at long 160 W
Australia - Japan
1808Saturn 9 Dec 20:35 UT20oW6", 14", 16"Barely Overlap if
seen at South Pole
2067Neptune15 Jul 11:57 UT18oW6", 2" ,10"Occultation only
at North Pole
with 24 hr daylight
2079Mars11 Aug 1:30 UT11oW5", 4", 1"Visible at Sunrise in Middle East
2088Jupiter27 Oct 13:46 UT5oW5", 29", 19"Too Near the Sun
2094Jupiter7 Apr 10:46 UT2oW5", 31", 6"Too Near the Sun
2126Mars29 Jul 16:07 UT9oW5", 4", 5"
2133Venus3 Dec 14:10 UT4oE 5", 63", 37"Venus Large but
Very Near the Sun

Mutual Occultation of Superior Planets

These are rare events indeed!!! There are fewer on these type of events because these planets do not move as much among the stars. It is unfortunate because they are alway much easier to observe since they occur at greater elongation from the Sun. In the period that Albers looked (1557-2230) all involved Jupiter, none involve Saturn, and only one involves Mars. I have added three Mars events prior to 1613 and one after 2223 from a table produced by GUIDE 7.0

from the Sun

and Separation
Comments on
19 Sept 20:44UT
Julian Calendar
105oE11", 42", 13" Observations recorded
by Gevase of Canterbury
and observers in China
30 Sept 00:14 UT
Julian Calendar
18 Oct 15:15 UT
Julian Calendar
7 Feb 8:15UT
Julian Calendar
4 Jan 2:08 UT108oW36", 2", 4"Neptune not discovered yet
Galileo Observed Jupiter Dec 28
but labeled Neptune as a star
15 Aug 17:03 UT9oW29", 4", 5"
Uranus yet to be discovered
19 Sep 13:26 UT165oW46", 3", 3"Neptune not discovered yet
2 Dec 12:39 UT89oE9", 38", 21"836 years
since last one
29 Aug 23:11 UT255 years
since last one

Jupiter and Saturn

Gray (Project Pluto) in a scan over the period -1000 to 6000 did not find a single case where Jupiter and Saturn had a mutual occultation. He looked for close conjunctions and found the closest at 424 BC.

There will be a close approach of 6' arc of the two in 2020 and hence will give a telescopic view of the two together. The Date of the event is 21 December 2020, at 18 h UT.
View of the Two as Seen in a Field of View of 0.3 degrees

Larry Bogan - Feb 12 , 1999