Re: [Utah-astronomy] Encke vs ISON (Was: Comet 2/P Encke)
WRT Encke not having much of a tail, it's been through so many perihelion passages that I didn't assume it ever had much of a tail (its orbit is such that it passes perihelion about every three years, iirc) One of those ho-hum; been-there-done-that comets. Then a quick search reveals one image that does have a tail, but it's not taken from earth's surface, but by the STEREO solar satellite mission: http://www.nasa.gov/mission_pages/stereo/news/encke.html All the other pictures a quick search turned up show just a nucleus and an offset coma. So take your pick: viewing angle or just not very active--may be a combination of both this perihelion passage, but it does look like it's appeared tail-less on prior passages also. JMC
More info on Encke's appearance in earlier apparitions is given on this page: http://cometography.com/pcomets/002p.html I found it particularly interesting that as far back as 1822 (its first predicted return), observers viewing it a couple of weeks after perhelion described it as: "like a faint nebula of a round form" and somewhat later as having "the same nebulous, orbicular appearance as when first seen." This was also an interesting note: "The comet's longest recorded tail length was 3 degrees in 1805, while it reached 2 degrees in 1871 and 1961." So, not an impressive tail in modern times ever, it would seem. John
How close does it actually come to earth, historically? Even a stub of a tail can appear big if it's close. On Mon, Oct 21, 2013 at 9:24 AM, John M. Craig <jmcraig@xmission.com> wrote:
More info on Encke's appearance in earlier apparitions is given on this page:
http://cometography.com/**pcomets/002p.html<http://cometography.com/pcomets/002p.html>
I found it particularly interesting that as far back as 1822 (its first predicted return), observers viewing it a couple of weeks after perhelion described it as: "like a faint nebula of a round form" and somewhat later as having "the same nebulous, orbicular appearance as when first seen."
This was also an interesting note: "The comet's longest recorded tail length was 3 degrees in 1805, while it reached 2 degrees in 1871 and 1961."
So, not an impressive tail in modern times ever, it would seem.
John
______________________________**_________________ Utah-Astronomy mailing list http://mailman.xmission.com/**cgi-bin/mailman/listinfo/utah-**astronomy<http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy>
Send messages to the list to Utah-Astronomy@mailman.**xmission.com<Utah-Astronomy@mailman.xmission.com>
The Utah-Astronomy mailing list is not affiliated with any astronomy club.
To unsubscribe go to: http://mailman.xmission.com/**cgi-bin/mailman/listinfo/utah-**astronomy<http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy> Then enter your email address in the space provided and click on "Unsubscribe or edit options".
participants (2)
-
Chuck Hards -
John M. Craig