Tidal stresses mean more pull on one part than another, which causes an internal separation force. The pieces thus are under slightly different accelerations when they come apart.

Thermal stresses can cause fracturing as different parts expand and contract differently. The internal stresses from the different contractions would provide pushes to separate the pieces.

Rocket effect from escaping gases is probably most significant. The comet is made of ices, which are melting from the added heat. As they melt, they shoot out in a jet or plume. That jetting causes a force. As the pieces separate, they are under different jetting forces and thus get pushed around in different ways.

Then there is the “Rocket effect” that happens because of the sublimation of the ice into gas.

I finally found it with my 10″ Skyquest Dobsonian early this morning.

Light Pollution is really a big issue here in seeing it or not seeing it.

It’s the light pollution man and I don’t much like how spaceweather.com is hyping it…it would be good if not for the light pollution.

Incedentally, according to Greg Crinklaw, it’s naked eye now. But I cannot verify it though.

That, or my latitude is too far north; NC.

.. Wonder how long its got left – eventually all comets fall apart or become quiescent (sp?) and efefctively transform themselves into extinct comets aka asteroids, meteor showers, or / & the dust that forms the zodiacal light. (Good luck trying to spot that from urban skies! )

Those interested in this may want to read up on another prominent historic disintegrating comet – Biela which fell to bits in I think around the 1840′s? Astronomers saw it split in two, one fragment was recovered -once then it became nothing but a meteor shower.

A lot of the sun-grazing comets are also the fall-out (or fall-apart may be a better term) of larger comets breaking into fragments – was an ‘Astronomy’ mgazine article on this recently … If my memory serves, I think they concluded + something like that one gargantuan comet hundreds of thousands of years ago created something like 60 % of all sun-grazing comets.

+ From tracing back orbital trajectories plus maybe some spectroscopic analysis?

Thanks Phil for the 411!

Curious…

How many of you belong to the International Dark Sky Assoc.?

How about you Phil do you belong?

If it’s still going to be around for the next new Moon, I might just haul my scope out to a dark site and try to photograph it, though…

“Seeing” has not been the best either during the last few days.

Tom

I hope to see it.

People in my group who couldn’t remember the name Schwassmann-Wachmann started referring to it as “Swashbuckle-Washboard”

Naturally, I’m not the guy with the answers on this. (Again, I refer you to the screen name.) But Phil over at Bad Astronomy has what seems like a reasonable explanation to me. …

“Immense” is relative, isn’t it? I mean, it wouldn’t be enough force to break me up, if I made a close approach to Jupiter.

According to this, the closest approach was 0.38 Jupiter radii, so one calculates the tidal force at 1.38 Jupiter radii (pretty close to 100,000 km).

If I have done the math right (force equals GMmr over big R cubed), I get an acceleration of 1.3E-7 newtons per kilogram, per meter of distance across the stretched body. This is about 1.3E-8 g per meter.
That’s about 25 nanogees across my body, or 13 microgees across the width of a 1-km comet nucleus.

Michael A’Hearn gave a Deep Impact talk here the other day, and mentioned that the interior of Comet Tempel 1 seemed to have the strength of talcum powder. So maybe a few microgees could tear it apart. But “immense” isn’t the word I’d use.

/barrum-chish (rimshot)

But seriously, folks, I’ll be looking through my binocs tonight.

There was just a faint smudge through my binocs, with no nucleus visible at all. I will almost certainly go for it with my telescope tonight.

Or, I could just see if Chabot in Oakland is doing anything.