Good period to observe Iapetus

[Nik271]

Last night I got out at 3am to view Saturn and Jupiter. There was a light haze which dimmed the gas giants a bit but the seeing was good and I could see quite a bit of detail, the Cassini division on Saturn and several belts on Jupiter. All four of the Galileans moons were grouped very close to Jupiter which was an unusual sight for me.

The other notable observation was Iapetus, the two faced moon of Saturn. It is now directly 6.5' west of Saturn and Titan is right in the middle between Saturn and Iapetus.

In addition this is the time when Iapetus is at its brightest, I believe it  is at mag 10 now, easily visible in my Skymax 127 even in astronomical twilight. This will persist for several weeks, after which Iapetus swings east of Saturn and dims considerably to magnitude 12. So now is the best time to observe it. Here is a screenshot from Stellarium for the coming night, at 1am on 15 July:

 

 Iapetus was discovered by D Cassini in 1671, and he noticed that the moon disappears when east of Saturn. His telescope was not powerful enough to spot it when at its dimmest. 

Nowadays we know that Iapetus has a dark side which is turned toward us at this part of its orbit. There are some interesting theories about its formation:

https://en.wikipedia.org/wiki/Iapetus_(moon)#Two-tone_coloration

Iapetus is the moon where the second monolith was located in Clarke's book  '2001: A Space Odyssey'.  (In the film and subsequent books the monolith was around Jupiter.)

[John]

Nice report and heads up on Iapetus

I can't help thinking of 2001: A Space Odyssey when I observe Iapetus as in "Oh my God, it's full of stars"

I find Enceladus an interesting challenge as well but for the opposite reason really - it's close in to Saturn so needs to be positioned favourably to pick it out of the glare of the planet.

 

 

Edited July 14, 2021 by John