Comparison of physical size of C17P, Sun, Jupiter, Earth

Here's my shot a figure showing the relative physical sizes of Comet
17P, the Sun, Jupiter and the Earth:

http://gallery.utahastronomy.com/d/1.../C17P_Size.PNG

Table of conversions from size to pixels used in figure

C17 Sun Jupiter Earth Moon
Km 1409918 1391000 142984 12756 3474
Pixels 383 378 39 3 1

- Canopus56

On Tue, 06 Nov 2007 17:23:57 -0800, canopus56
wrote:

Here's my shot a figure showing the relative physical sizes of Comet
17P, the Sun, Jupiter and the Earth:

http://gallery.utahastronomy.com/d/1.../C17P_Size.PNG

Nice. I've updated my page at
http://www.cloudbait.com/gallery/comet/holmes.html with data from last
night. The growth rate of the dust coma is absolutely linear, and
corresponds to a constant 1104 m/s - about twice what Hyakutake
experienced at its peak. The current diameter of the dust coma is about
2.8 million km, twice the size of the Sun. Of course the entire coma
with its outer gas regions is much larger yet.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Nov 7, 1:07 pm, Chris L Peterson wrote:
snip
Nice. I've updated my page athttp://www.cloudbait.com/gallery/comet/holmes.htmlwith data from last
night. The growth rate of the dust coma is absolutely linear, and
corresponds to a constant 1104 m/s . . .

Thanks, Chris. Is there a median diameter of how large a coma that
comets typically expand to? Is 17P unusual, or have I just not been
doing similar computations for other comets? - Canopus56

On Wed, 07 Nov 2007 14:48:59 -0800, canopus56
wrote:

Thanks, Chris. Is there a median diameter of how large a coma that
comets typically expand to? Is 17P unusual, or have I just not been
doing similar computations for other comets? - Canopus56

I don't really know. The dust ejection rate (which should be 550 m/s,
not 1100 m/s) is consistent with high activity comets closer to the Sun,
so there's no reason comas shouldn't reach a similar size as long as the
nucleus can provide enough material (which in terms of mass isn't all
that much).

I wonder if one reason this comet has such a large coma is that at 2+
AU, the solar wind is much less efficient at dragging lots of it off
into a tail.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Nov 9, 11:12 am, Chris L Peterson wrote:
I wonder if one reason this comet has such a large coma is that at 2+
AU, the solar wind is much less efficient at dragging lots of it off
into a tail.

Thanks, Chris. Very good point. - C

On Tue, 06 Nov 2007 17:23:57 -0800, canopus56
wrote:

Here's my shot a figure showing the relative physical sizes of Comet
17P, the Sun, Jupiter and the Earth:

http://gallery.utahastronomy.com/d/1.../C17P_Size.PNG

And still growing linearly. Measurements made last night show that there
has been no change in the ~550 m/s dust ejection rate. That is, the
comet's diameter continues to grow by 1.1 km/s.
http://www.cloudbait.com/gallery/comet/holmes.html

The total brightness (that's irradiance for Paul Schlyter g) seems to
be increasing still, although the brightness per unit area (radiance) is
decreasing. Visually, the comet appears less bright.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Nov 10, 4:52 pm, Chris L Peterson wrote:
The total brightness (that's irradiance for Paul Schlyter g) seems to
be increasing still, although the brightness per unit area (radiance) is
decreasing. Visually, the comet appears less bright.
Chris L Peterson
Cloudbait Observatoryhttp://www.cloudbait.com

Based on visual data from a Cloudy Night's observer early in the
outburst, I also calculated the rate of coma increase at ~ 1.15 kms.

http://www.utahastronomy.com/Current...7P_size_change

- Canopus56

On Nov 10, 5:38 pm, canopus56 wrote:
On Nov 10, 4:52 pm, Chris L Peterson wrote:
Based on visual data from a Cloudy Night's observer early in the
outburst, I also calculated the rate of coma increase at ~ 1.15 kms.
- Canopus56

P.S. - That's the rate of the increase in diameter of the coma
~1.15kms. 1/2 that amount is ~ 507 meters/s for the radius expansion
- or the speed of dust ejection as you term it on your web page. -
Canopus56