moons of Uranus

[nytecam]

My routine 5s exposure to record the outer moons of Uranus in Aquarius via my Lodestar camera on my Classic Meade 30cm SCT - fainter Miranda and Ariel lost in glare of planet.  Moon ID via Cartes du Ciel - data on image.

Nytecam

[laudropb]

very nice capture. Well done.

[RobertI]

Very nice capture, I wonder if Oberion has a slightly inclined orbit as it does not seem to be in line with the other two?

[nytecam]

Very nice capture, I wonder if Oberion has a slightly inclined orbit as it does not seem to be in line with the other two?

Robert - I don't read it that way. The orbits of the sats are highly inclined ellipses from our viewpoint and all 3 east (lelt) side of the ellipse on this occasion moving in anticlockwise direction :-)

Nyte

[RobertI]

Robert - I don't read it that way. The orbits of the sats are highly inclined ellipses from our viewpoint and all 3 east (lelt) side of the ellipse on this occasion moving in anticlockwise direction :-)

Nyte

Looking closer I can see that my initial analysis was flawed! I cant' quite picture your explanation but I'm sure you are right - I'll investigate a bit further to try and get a clearer picture.

Rob

[nytecam]

Robert - my Cartes du Ciel doesn't plot the orbits but other s/w may. As Uranus' poles are inclined >90degs the sat motion may be clockwise ! I could check this by running CdC for advancing hours to see their movement !

Nytecam

[RobertI]

Ok, I think I have it, viewed from above the satellites' orbits are largely circular and in the same plane like this:

But viewed from Earth the plane is at an acute angle like this:

I think that clarifies it for me, thanks for the pointers.

[Pete Presland]

Very impressive capture.

[nytecam]

Robert - excellent presentation of the Uranian sat orbits ;-)  As the orbits seem essentially circular, I'm surprised they show, as apparently viewed from earth,  'perpective' as if close to the planet but I may be wrong !

Here's Uranus' sats from last night [and placed correctly in Pisces and not Aquarius!] and Neptune and Trition in Aquarius. 

Interestingly almost all bodies in the solar system axially spin and orbit, whether planet or satellite, in the same anticlockwise direction but Triton uniquely bucks the trend for a large body !

Nytecam

[Martin Meredith]

Great captures, really impressive; and an interesting discussion with Rob. I notice Pal 2 features in one of the planetarium screen captures… difficult to tell from the perspective if it is sufficiently close to catch in the same field?

Martin

[RobertI]

Robert - excellent presentation of the Uranian sat orbits ;-) As the orbits seem essentially circular, I'm surprised they show, as apparently viewed from earth, 'perpective' as if close to the planet but I may be wrong !

thanks . Having played a bit more with Sky Safari's 'orbit' mode, I think you are absolutely right, the perspective is created because it is simulating being close to the planet, if I zoom out the perspective becomes diminished to being symmetrical either side of the planet. Seems obvious now I think about it! I'm pretty sure the angle of the orbital plane is correct though.

Martin - unfortunately I think Sky Safari is misleading us there, I'm not quite sure what it is doing with the background star fields when in 'orbit' mode, but Pal 2 is no where near it in the sky when in 'normal' view!

Rob

[Martin Meredith]

Rob, yes, just checked that it is in Auriga!; so I'm guessing it is simply the backdrop if one was viewing Uranus from that perspective. I see Aldebaran is there too in the correct position re Pal 2….

Martin

[nytecam]

Thanks Rob for the  Sky Safari projection mode - it's still amazing s/w !

Here's Uranus [5s exp] + Neptune [8s exp] and their sats from last night through haze/cirrus - wanted to catch Triton again within 24hrs to see its motion ;-)

Note how Neptune [it's passed opposition] is 'moving' east again to left caused by earth's much faster inner orbit motion whilst Uranus is moving west [retrograde motion] against the star backgrounds !  This is apparent over just a few hours as earth 'thunders' along its orbital track whilst we down here feel nothing of this motion !

Nytecam