The big and the small of comet 46P

[Size9Hex]

Intrigued by comments that 46P/Wirtanen appears as large visually as the full moon, I checked some numbers on Sky Safari. The comet is 12M km away and the moon just 400k km, which would seem to say that the comet is 30 times larger in diameter than the moon - not far off the size of Saturn! Can this really be true? ?

Anyway, it was delightful comparing the view in the 72mm frac at 18x magnification against the 10" dob at 180x. They both showed something the other couldn’t!

In the frac, the comet was smaller in apparent size as per intuition, but greater in physical extent across the sky - I could see more of it. The heart appeared a little like an out of focus star superimposed on the larger fainter extent of the comet. I initially thought the object was weighted on one side, but it seemed symmetrical on returning to it later, so I suspect this was a mistake.

If the comet is as large as the moon, my 6.7mm eyepiece in the dob should have been entirely filled with comet! I saw a fairly large glow, which I now wonder might have been the "out of focus star" at the comets heart that I had seen in the frac. At the heart of this heart was another (almost?) stellar glow. The object was somewhat lopsided at this power, trailing away to the bottom right of the eyepiece.

I didn’t get any impression of something that appeared to be there a few nights ago; That of a small wedge shaped glow just behind the brightest part of the comet. Only moderate confidence in that observation of the wedge, although I did later see a sketch on CN with a couple of spikes/jets angled in the same way, so perhaps there was something?

Hope everyone else gets some good views too! ?

[happy-kat]

Those are interesting thoughts.

Saw it tonight in binoculars it was much larger and more diffuse when compared to what had seen of Lovejoy.

[goodricke1]

Yes it really is that large; during Comet Holmes' outburst in 2007 it was bigger than the Sun.

[Size9Hex]

3 minutes ago, goodricke1 said:

Yes it really is that large; during Comet Holmes' outburst in 2007 it was bigger than the Sun.

Wow, that’s really something! Thanks for the reply. I hadn’t realised they could be so huge.

[Ed in UK]

Managed to see this comet in the early hours of this morning and really pleased that I was able to find it.

If we get another chance soon, I'll drop on it again and see if I can see more, I went down to x75 (12mm) but I was only looking to see if i could see any movement in the comet.

Sounds interesting.

[Eastman]

On ‎13‎/‎12‎/‎2018 at 19:19, Size9Hex said:

Anyway, it was delightful comparing the view in the 72mm frac at 18x magnification against the 10" dob at 180x. They both showed something the other couldn’t!

Nice comparison, I have only seeing it with the 20X60 bins. The last few day it is unfortunately very cloudy. Would like to see it with the 10"dob.

Great sketches.

[Size9Hex]

45 minutes ago, Eastman said:

Nice comparison, I have only seeing it with the 20X60 bins. The last few day it is unfortunately very cloudy. Would like to see it with the 10"dob.

Great sketches.

Fingers crossed for some good weather for you. It’s a nice view in the 250px. Looks like the next few days might be affected by the moon, even if it wasn’t cloudy, but hopefully some clear skies just after Christmas when the moon is out of the way again.

[FenlandPaul]

A really interesting comparison! It’s great when objects reward you in different ways with different instruments.

I just popped out with the 70ed to see if I could track it down near the Kids in Auriga, but the full moon within 20 degrees and the hazy sky have obliterated my chances tonight!