Jovian-Dual Shadow Transit for October 31, 2011

Remarkable was the dual-shadow transit on October 24. But, there is yet another and unfortunately the final dual-shadow transit of Jupiter in 2011. October 31 will bring us one more "astronomical morsel" and this one will be presumably about the same as the last: Io will transit just beneath the waistline of Jupiter, and Ganymede at the exact bottom of the king of the planets. Both of the shadows will be cast on the planet for only sixteen minutes, from 18:10 to 18:26 UT. This will be during the day for Washington DC, at approximately 1:10 to 1:26 EDT. Although this is rather sad, the eastern world will be able to witness the last Jovian dual-transit for the great year of 2011. A comprehensive photo shoot (courtesy of The Transits Page) is shown at the end of this article. Below is a picture of the Jovian moons at 00:00 UT on October 31, 2011, or at 8:00 October 30, for us here in EDT.

Image Credit: Transits Page; Text entered by AstronomicalEventsCalendar

Callisto beautifully rests on top of the planet, as it's orbit appears to be above the planet, we must remember that these orbits are three dimensional - and that since Jupiter is titled towards us, it looks like Callisto orbits above. Sense Perception! Concerning the transit, you can see Io and Ganymede - Ganymede will swoop down and catch up to Io (they are not actually that far apart in the two-dimension scale, becasue of their orbits, but they appear to be far apart). The dual-transit itself will start at 17:46 UT and end at 18:22 UT, lasting only 36 minutes. If you can remember, this is very shorter than the October 24 transit.The next picture below concerns itself right before the transit - at 16:00 UT. Ganymede and Io are now very noticeable together.

Image Credit: The Transits Page; Text entered by AstronomicalEventsCalendar

If you're wondering what a Jovian dual-sahdow transit is? Look no further - Here, we can clarify the terms of dual-shadow transit, and dual-transit, becasue both can happen at the same time - the October 24 and 31 transits are great examples of these (among others). A dual-shadow transit occurs when two shadows of moons travel across the surface of Jupiter together (and yes this can also happen on any other planet with two or more moons, etc.), and then, when the two moons travel together, it is called a dual-transit. (The difference is just either the shadow or moon), but both have to cross Jupiter (or any other planet, etc.) at the same time. You can read more about Jovian transits in our last transit: October 24.

-all pictures below are credit The Transit's Page, Galilean Moons Simulator; text entered by myself-

Another object to note is the conjunction of Io and Ganymede again, but the next day:
2011-Nov-01 05:19 Conjunction of Io and Ganymede [144.0" W; 21.7" S].

TOTAL EVENTS FOR OCTOBER 31, 2011
2011-Oct-31 15:12 Conjunction of Io and Ganymede [44.7" E; 13.1" S]

2011-Oct-31 16:13 Transit Ingress of Io (All satellites no more visible to the east of Jupiter)
2011-Oct-31 16:18 Shadow Transit Ingress of Io
2011-Oct-31 17:18 Inferior conjunction of Io
(2011-Oct-31 17:45 Conjunction of Callisto and Europa [204.4" E; 38.1" S])*
2011-Oct-31 17:46 Transit Ingress of Ganymede (Double Transit Begin)
2011-Oct-31 18:10 Shadow Transit Ingress of Ganymede (Double Shadow Transit Begin)
2011-Oct-31 18:22 Transit Egress of Io (Double Transit End)
2011-Oct-31 18:26 Shadow Transit Egress of Io (Double Shadow Transit End)
2011-Oct-31 18:30 Inferior conjunction of Ganymede
2011-Oct-31 19:09 Transit Egress of Ganymede
2011-Oct-31 19:24 Shadow Transit Egress of Ganymede

*Object of Note!
(with thanks to the Galilean Moons Simulator)

Jupiter at Opposition October 29, 2011

This October 29, Jupiter will reach the closest to earth, making observation excellent on cloudless nights. It is the closest approach the planet will ever get to earth between the dates of 1963 and 2022, so now is the time to study the king of the planets. On this day, earth will pass directly in between the Sun and Jupiter, making Jupiter the brightest, becasue it's closest. Although on this date the planet will be the brightest, it will be more noticed in November due to its movement in the sky. Currently, this planet is about 35 degrees from the horizon in the east, and the Galilean moons are very easy to view - even with binoculars.

Jupiter, taken by the Cassini space probe

Shining at magnitude -2.9, Jupiter is in Pisces and is 49.7 arc-seconds across. At 18:44:21 UT, Jupiter is at greatest opposition, being 3.96976 AU (Astronomical Units, distance of earth to sun, or 93 million miles) from the planet. This is 369,012,245.45797 miles away, respectively. What times can I see Jupiter? This is an excellent question - Jupiter is at opposition, therefore meaning that Jupiter will be visible all night. (Even when the moon is full, Jupiter is still bright and beaming!).

Jupiter, as seen by the Cassini space probe (the back spot on the planet is Europa's (moon) shadow)

Where Jupiter is in relation to the constellations

Viewing the Galilean Satellites

As some readers might note, Jupiter's moons are a big point of interest here at Astronomical Events Calendar. (We have even a blog dedicated to them). With just simple binoculars, you can make out all for of the Galilean moons: Io, Europa, Ganymede, and Callisto. The past few nights, I have seen the moons fairly easily and you can too. But how do I know which moon is which? As a general rule of thumb, the innermost moon is Io, the second Europa, then Ganymede, and Callisto's orbit is the farthest; all these moons, though, are at different positions and therefore hard to discern without a very strong telescope lens (you can tell by color, then) or a map of where the moons will be.

Sky&Telescope provides a "wobble*" map, showing where these moons will be in relation to Jupiter. Below are some pictures of where these moons will be positioned on certain dates.

Jupiter will be visible in the sky through the rest of 2011, but note that it will be getting dimmer. Note that Jupiter will be the closest to earth only this year until 2022 again, and keep an eye on the glorious moons of our favorite planet: Jupiter!

*for November

Results of the October 24, 2011 Jovian Dual Transit

The dual-shadow transit on October 24, this past Monday was a true spectacle! Although we here in America could not view such a wonderful event, I have been able to find a few pictures scattered across the internet of this spectacular event. About the transits: "After having such a prolific season of simultaneous Jovian dual-transits last May-June, it will be hard to accept the fact that we have only two more this 2011 season: October 24, 2011 and October 31, 2011. Each transits are an exact week apart (although times differ) and both are dual-shadow transits. Io and Ganymede both partake in each event, as their orbits must be aligned perfectly just for this week." Read more at the link above.

This picture was taken from 'Cloudy Night Telescope Reviews' under username 'claytonbigwood'

Below is a picture computed (simulated) by Celestia software. You can see Ganymede and Io as the light blobs, and their shadows cast on the planet. If you would to see the picture clearer, you may click on it for higher resolution.

Although these are not the most high quality images available, they do beautifully illustrate the beauty of this transit. Remember that October 31 brings us another galactic delicacy! Another dual-shadow transit awaits us...

December 27, 2011 Dual-Shadow Transit

According to the "Robert Ferguson Observatory," they state in their 2011 Observing highlights, that there will be a dual-shadow transit of Europa and Ganymede on December 27, 2011. Although I do recommend their observing highlights to those who would like to know, their event is incorrect. They have:

• Tuesday, 12/27/2011 - Dbl Sh Tr Jup - Time: 18:00
• Double shadow transit of Jupiter:
  Transit of Europa is already in progress at sunset.
  06:00p Nautical twilight ends
  06:05p Ganymede's shadow begins transit
  06:32p Astro twilight ends
  07:44p Io is occulted by Jupiter
  07:51p Europa's shadow begins transit
  07:52p Europa transit ends
  07:55p Ganymede's shadow transit ends
  10:15p Europa's shadow transit ends
  11:07p Io reappears from eclipse

Although I do not wish to refute this prediction, after checking the Galilean moons simulator, they're prediction is wrong. Ganymede does transit and Io does eclipse, but Europa is just too far away from Ganymede for dual-shadow transit. Without making any advanced Judgments, this may occur, but maybe if viewed from a different angle on the earth.

Computer Simulation of Galilean moons provided by the Galilean Moons Simulator, Text Inserted by AstronomicalEventsCalendar

Jovian Dual-Shadow Transit of October 24, 2011

After having such a prolific season of simultaneous Jovian dual-transits last May-June, it will be hard to accept the fact that we have only two more this 2011 season: October 24, 2011 and October 31, 2011. Each transits are an exact week apart (although times differ) and both are dual-shadow transits. Io and Ganymede both partake in each event, as their orbits must be aligned perfectly just for this week. According to Simultaneous Transits of Galilean satellites and their shadows across Jupiter during 2011, a paper that lists each of dual-transit phenomena in full (can be found here), the October 24 dual-transit is the longest of the two (the other being October 31, respectively) with both moons transiting over 1 hour 18 minutes, with both shadows on the planet over the span of 58 minutes. A comprehensive photo shoot (courtesy of The Transits Page) is shown at the end of this article.

Image Credit: Transits Page; Text entered by AstronomicalEventsCalendar

Looking at the above image, we see the Galilean moons on October 24, 2011 at 00:00 UT (times forth are Universal Time, or UT). The transit begins 14:22 UT and ends comprehensively at 15:20 UT - a rather long dual-transit at 1 hour and 28 minutes, although the longest was on January 10, 2011 (2 hrs & 15 min). The next image shows the Jovian satellites at 14:00 UT, on the same date. Note how close Io and Ganymede are, and the shifting of Callisto and Europa.

Image Credit: The Transits Page; Text entered by AstronomicalEventsCalendar

In the above image, you can see Io and Ganymede about to enter transit. Callisto has shifted further away from Jupiter as it completes its orbit, and Europa is shifting down, as its orbit is completed. During transits with Ganymede, because of Ganymede's orbital eccentricy, it orbits near the south pole of Jupiter, making transits involving it shorter than transits with Europa. Europa and Io orbit very closely around the belt line of Jupiter, making dual-transits more facile; Callisto only dual-transited once this year, on January 10 (which was the longest, partially becasue Callisto is the farthest moon, and orbits slower than Europa, who shared the transit. Other than that, only Io transits the rest of 2011, with either Ganymede or Europa, see for yourself here.)

Before the transit begins, at 04:19 UT, Io and Ganymede will conjunct, as the picture below (first) shows us. Celestial Coordinates: [145.1" E; 20.6" S]. On the timing of the transit, Ganymede's shadow will ingress first at 14:06 UT (note before the actual dual-transit begins), and then Io's will at 14:22, signifying the start of the dual-transit. From there, Io will start its journey across Jupiter's luminous disk at 14:29 UT, and Ganymede at 14:34, starting the dual-transit of the moons.

Here, we can clarify the terms of dual-shadow transit, and dual-transit, becasue both can happen at the same time - the October 24 and 31 transits are great examples of these (among others). A dual-shadow transit occurs when two shadows of moons travel across the surface of Jupiter together (and yes this can also happen on any other planet with two or more moons, etc.), and then, when the two moons travel together, it is called a dual-transit. (The difference is just either the shadow or moon), but both have to cross Jupiter (or any other planet, etc.) at the same time.

You can see most of the events of this transit below, computer simulated, becasue 14:22 UT is 10:22 EDT; we here in America will not be able to view this transit (neither the 31). You can convert times here. {This is a rather sad fact for us here in America, but for those in East Asia, the Pacific, and some of the Middle East will enjoy seeing this treat. Jupiter here in America is high during night - and at Opposition, and it's very sad that we won't be able to see it!}

-all pictures below are credit The Transit's Page, Galilean Moons Simulator; text entered by myself-

 

 

TOTAL EVENTS FOR OCTOBER 24, 2011

2011-Oct-24 00:16 Conjunction of Europa and Ganymede [194.4" E; 27.3" S]
2011-Oct-24 04:19 Conjunction of Io and Ganymede [145.1" E; 20.6" S]
2011-Oct-24 04:48 Transit of Great Red Spot
2011-Oct-24 05:00 Eastern Elongation of Io, 145.9"
2011-Oct-24 08:27 Eastern Elongation of Europa, 235.1"
2011-Oct-24 14:06 Shadow Transit Ingress of Ganymede
2011-Oct-24 14:22 Shadow Transit Ingress of Io (Double Shadow Transit Begin)
2011-Oct-24 14:29 Transit Ingress of Io
2011-Oct-24 14:34 Transit Ingress of Ganymede (Double Transit Begin)
2011-Oct-24 14:44 Transit of Great Red Spot
2011-Oct-24 15:16 Inferior conjunction of Ganymede
2011-Oct-24 15:20 Shadow Transit Egress of Ganymede (Double Shadow Transit End)
2011-Oct-24 15:34 Inferior conjunction of Io
2011-Oct-24 15:52 Transit Egress of Ganymede (Double Transit End)
2011-Oct-24 16:09 Conjunction of Io and Ganymede [12.5" W; 13.1" S]
2011-Oct-24 16:30 Shadow Transit Egress of Io
2011-Oct-24 16:38 Transit Egress of Io

(With thanks to Galilean moon Simulator).

Last Two Jovian Dual-Transits for the 2011 Season

Although it is rather sad, the last two Jovian dual-transits will take place respectively on October 24 and 31, 2011; always a sempiternal treat! Apparently, the Jovian moons are falling back to imperfect resonance (to cause them not to be aligned perfectly), but the orbits are never too imperfect; more than likely, their orbital Saros has ended. It is a misconception to think that only earth's moon has a Saros, but indeed other moons do as well. For eclipsing (or transiting, respectively!) all moons need a Saros pattern, and even though one hasn't been established (that I am aware of), it still follows this Saros.

Figure 1 - The Orbital Resonance of the Jovian moons.

A Jovian dual-transit is a rare and exciting phenomena that occurs when two (or more) of the Jovian moons pass in front of Jupiter, passing together and usually casting shadows. Below is such an example, and below that is a picture of a Jovian triple-transit; quite an event.

May 7, 2011 dual transit provided by the transits page.

March 28, 2004 triple Jovian transit. The fourth black dot is actually a moon itself, casting a shadow.

As we begin to wait for the moons to dual-transit one last time in 2011, let us make known the occurrence of such events. In the Dual-Transits Ephemeris provided by the transits-page, in 2011, eighteen dual transits occur, but twenty dual-shadow-transits occur. This is important to note: the difference between the dual-shadow transit and the plain dual-transit.

Jovian dual-transit - the transit of two or more Jovian moons across the face of Jupiter, usually very long due to the fact of their shadows

Jovian dual-shadow transit - the transit of two or more Jovian moons across the face of Jupiter, with shadows, so the length would be shorter

According to these definitions, if two moons transit, with two shadows transiting as well as moons (Jovian dual-shadow transit) four spots may appear on the planet (Jupiter), though most of the time it's just the shadows that occur. You can read more at the link provided above. More information will be provided in the coming days - ON THIS SITE. Thank you!