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Go Back   IceInSpace > General Astronomy > Celestial and Astronomical Events

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  #1  
Old 02-02-2009, 05:13 AM
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iceman (Mike)
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Exclamation Upcoming Transits of Titan at Saturn - February and March 2009

Transits of one of Saturn’s Moons or the Moon’s shadow across Saturn’s disk are very rare events. Due to the tilt of the ring plane, we are only able to observe these events once every 14-15 years, when the rings are “edge on” as seen from our location on Earth.

Right now, we are in the middle of a “ring plane crossing” and in 2009, there are 4 visible transits of Saturn’s largest Moon, Titan, across the face of the planet. The first one occurred on January 24th, and I was fortunately able to capture 3 images to create an animation.

There are 3 more upcoming transits of Titan across the face of Saturn:
  • February 9th: Approx 1am Sydney AEDST (February 8th 1400 UT)
  • February 24th: Approx 11:15pm Sydney AEDST (February 24th 1215 UT)
  • March 12th: Approx 10:15pm Sydney AEDST (March 12th 1115 UT)
Continue reading to find out more, where to find Saturn, and to see a simulation of where you will see the Titan and its shadow on the face of Saturn.

Upcoming Transits of Titan at Saturn - February and March 2009

I hope you get clear skies to observe (and photograph, if that’s your thing) these rare events! Please post your observing reports here and your images in the Solar System section.

Last edited by iceman; 02-02-2009 at 07:28 AM.
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  #2  
Old 02-02-2009, 07:28 AM
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Article uploaded.
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  #3  
Old 02-02-2009, 11:12 AM
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Thanks for the tip-off! One problem, particularly for city dwellers, may be that the moon is almost full on the 9th Feb. and will be sitting at the same angle above the horizon (about 30°). Saturn will be to the NE and the moon just slightly west of north at 0030 hrs. in Melbourne, when the transit of Titan is just beginning. The viewing should be better on the 24th when there is no moon, although Saturn will be about 5° lower. (Info courtesy Stellarium)
Robert
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  #4  
Old 02-02-2009, 01:27 PM
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Thanks of for the info.

I can't help wondering, however, why we aren't going to see any more transits this year. The ring plane crossing will last a while, surely Titan will transit a few more times than this?
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  #5  
Old 02-02-2009, 02:17 PM
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Thanks for this.
should make for some interesting nights.
well at least more interesting then im used to.
ah single life.
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  #6  
Old 03-02-2009, 03:48 AM
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Quote:
Originally Posted by Blue Skies View Post
Thanks of for the info.

I can't help wondering, however, why we aren't going to see any more transits this year. The ring plane crossing will last a while, surely Titan will transit a few more times than this?
hmm good point. The orbit of Titan is every ~16 days, so I guess you'd expect to see the transit every 16 days but after March 12th we don't see them until 2010.

Having a look in Starry Night Pro just then, it appears to be a combination of the rings opening back up again, so Titan passes below the disc, and the fact that the transit occurs 2 hours earlier each 16 days (the orbit is actually 15 days and 22 hours).

After March 12th, there's actually a Titan shadow transit on March 28th, while the Moon itself passes below the planet and that occurs at 8:46pm AEDST. Same again on April 13 and April 29 (the next 2 orbits). It appears to continue like this until Saturn is too low and too close to the Sun for us to observe. Also the shadow would start its transit 2 hours earlier each orbit, so it will be further across the planet each time until around July when the shadow transit is almost complete at the time the sun sets.

Thanks for asking the question - it prompted me to do some research and I actually learnt something!

Cheers
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  #7  
Old 03-02-2009, 11:34 PM
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Thanks for the answer, Mike. After I posed it I wondered if I had just been too lazy with my reading and should do my own homework, but I'm glad to hear there will be a few more opportunities in the future.
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Old 04-02-2009, 10:32 AM
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Hi Mike,

Thanks for posting the info.
Just had a look at the 9th and 24th with The Sky 6. It agreed with Starry Night for the 9th and also the 24th for the position of Titan, however it has Mimas also transiting on the 24th at the same time, just east of the CM at 12:15 UTC. Starry Night has Mimas east of the planet disk.

Starry Night shows the inner moons and also the shadow transits which The Sky does not, wondered how to go about confirming one or the other data sets regarding Mimas. I suppose on that morning if Mimas shows up or not will determine which is more accurate but I am surprised that they differ at all.

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Trevor
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Old 04-02-2009, 07:31 PM
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"Starry Night has Mimas east of the planet disk"
Daylight saving issue?
Mimas goes from CM to edge in about an hour.

gb.

Last edited by gb_astro; 05-02-2009 at 08:33 PM.
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  #10  
Old 05-02-2009, 09:28 AM
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Hi gb,
No, daylight saving is not an issue when comparing UTC date & time to UTC date & time.

At 12:36 UTC on Jan 8th Titan is at second contact, that is the disk of Titan is on the disk of Saturn and their limbs are in contact, just after the start of the transit.

At that time, according to The Sky 6, Mimas is transiting the disk of Saturn very close to the ring plane, probably in the EZn (Equatorial Zone north) on the far eastern side of the planet.

Regards
Trevor
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  #11  
Old 05-02-2009, 08:32 PM
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Hello Trevor.

Stellarium seems to be agreeing with The Sky:

On the 8th Feb Stellarium is showing Titan at second contact at about 12:15 UTC with Mimas about three quarters of the way across the disk.

On the 24th Feb at 12:15 UTC Stellarium is showing both Titan and Mimas near the CM.

(Is it really 37 degrees out there now?)

gb.

Last edited by gb_astro; 06-02-2009 at 12:22 PM.
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Old 07-02-2009, 01:35 PM
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Quote:
Originally Posted by gb_astro View Post
Hello Trevor.

Stellarium seems to be agreeing with The Sky:

On the 8th Feb Stellarium is showing Titan at second contact at about 12:15 UTC with Mimas about three quarters of the way across the disk.

On the 24th Feb at 12:15 UTC Stellarium is showing both Titan and Mimas near the CM.

(Is it really 37 degrees out there now?)

gb.
Hi gb,

Thanks for the comparison with Stellarium.
I would have thought most of these programs would have agreed with one another. Anyway it is good that there will be the possibility of imaging two moons simultaneously transiting Saturn.

Yesterday it was 42C in Broken Hill, today is predicted to reach 45C. According to our local ABC radio this will be our 12th straight day over 40C. Not sure how correct they are, I thought we were up to 18 straight over 40c days.

We are supposed to get a cool change Sunday down to 39C and next week it is supposed to get back to the high 20's.

Regards
Trevor
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  #13  
Old 08-02-2009, 01:42 PM
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Southerly change coming tonight, looking like it'll bring clouds and maybe rain.

Not good for a Titan transit night
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  #14  
Old 08-02-2009, 03:35 PM
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Quote:
Originally Posted by iceman View Post
Southerly change coming tonight, looking like it'll bring clouds and maybe rain.

Not good for a Titan transit night
Hi Mike,
Hope you do get some rain to help with the fires over your way.
Out here at Broken Hill the temp at 16:00 CSST has only reached 37.5 C. It feels much better than yesterdays 45 C. This has been our coolest day for about three weeks.

Not a cloud in sky at the moment and looking good for tonight / tomorrow morning.

Regards
Trevor
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  #15  
Old 08-02-2009, 06:13 PM
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Quote:
Originally Posted by iceman View Post
Southerly change coming tonight, looking like it'll bring clouds and maybe rain.

Not good for a Titan transit night
Southerly change should arrive Sydney around 10pm. Transit starts around midnight. Looks like another one to miss out on. But I will hang around just in case.
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  #16  
Old 10-03-2009, 12:32 PM
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Question

About 10 of us ASWArians got out to Whiteman park on Feb 24 to see the transit of Titan across Saturn that night. Looked like it was going to be a whiteout but it cleared for virtually the entire duration of the event. We got quite a good look at the shadow on our camera/monitor setup.

Will the transit on Mar 12 be visible in Perth or will Saturn be too low on the horizon for us to get a glimpse? And is that the same for the shadow transit on Mar 28? We'll be down at Dryandra for the ASWA Astrocamp that night and it would be something interesting to observe as a group.

Thanks,
HilB...
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  #17  
Old 10-03-2009, 08:04 PM
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I think the March 12th one is going to be below the horizon for us ie Saturn wont have risen in time. Not sure about the March 28th one, will be interested in the answer.

[edit] here's the answer: "After March 12th, there's actually a Titan shadow transit on March 28th, while the Moon itself passes below the planet and that occurs at 8:46pm AEDST. Same again on April 13 and April 29 (the next 2 orbits)." So that translates back to 6.46pm WDT, not good There is a two hour backslide each time (hope I've understood that right) so we've basically missed out chances here in the west for the time being if that is the case.[/edit]

p.s. there are two other threads on the Saturn/Titan transits a bit lower down where reports got posted if you're interested in finding out how other people fared a few weeks ago.
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