# Ursids

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> Markdown URL: https://mediated.wiki/source/Ursids.md
> Source: https://en.wikipedia.org/wiki/Ursids
> Source revision: 1328535157
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

{{Short description|Meteor shower}}
{{About||the bear family|Ursidae}}
{{Infobox meteor shower
| name               = Ursids (URS)
| image              = Radiant for Ursids 2018.jpg
| caption            = [Ursa Minor](/source/Ursa_Minor) with the [radiant](/source/Radiant_(meteor_shower)) of the Ursids marked in red
| pronounce          = 
| date               = 
| parent             = [8P/Tuttle](/source/8P%2FTuttle)<ref name="Kronk"/>
<!-- Radiant -->
| constellation      = [Ursa Minor](/source/Ursa_Minor) (near [Kochab](/source/Kochab))
| ra                 = {{RA|14|36}}<ref name=IMO/>
| dec                = {{DEC|+75.3}}<ref name=IMO/> ([Northern Hemisphere](/source/Northern_Hemisphere))
<!-- Properties -->
| month              = {{Nowrap|December 17 – December 26}}<ref name="Kronk"/>
| peak               = December&nbsp;22<ref name="Kronk"/>
| velocity           = 33<ref name=IMO>[https://www.imo.net/resources/calendar/#Ursids IMO Meteor Shower Calendar: Ursids (URS)]</ref>
| zhr                = 10<ref name="Kronk"/>
| notes              = 
}}

The '''Ursid''' (URS) meteor activity begins annually around December 17 and runs for over a week, until the 25th or 26th. This [meteor shower](/source/meteor_shower) is named for its [radiant](/source/Radiant_(meteor_shower)) point, which is located near the star [Beta Ursae Minoris](/source/Beta_Ursae_Minoris) (Kochab) in the constellation [Ursa Minor](/source/Ursa_Minor).

== History ==
The Ursids were probably discovered by [William F. Denning](/source/William_F._Denning), who observed them for several years around the start of the 20th century.<ref name="Kronk"/> While there were sporadic observations after, the first coordinated studies of the shower didn't begin until Dr. A. Bečvář observed an outburst of 169 per hour in 1945.<ref name="Kronk"/> Further observations in the 1970s and ongoing to current have established a relationship with [comet](/source/comet) [8P/Tuttle](/source/8P%2FTuttle).<ref name="Kronk"/> [Peter Jenniskens](/source/Peter_Jenniskens) and Esko Lyytinen discovered that outbursts could happen when comet Tuttle was at aphelion because some meteoroids get trapped in the 7/6 [orbital resonance](/source/orbital_resonance) with [Jupiter](/source/Jupiter).

== Technical information==
Earlier observations described an average radiant of RA={{DEC|217}}, DEC={{DEC|76}},<ref name="Kronk"/> with maximum occurring at a solar longitude of 270.66 deg (about December 22), with the duration being established as December 17–24.

The Ursids have a particularly narrow stream, prompting veteran meteor observer, Norman W. McLeod, III (Florida) to comment that the Ursids "must be a compact stream like the [Quadrantids](/source/Quadrantids). You have to be within 12 hours of maximum to see much."<ref name="Kronk"/>

== References ==
<references>

<!-- unused <ref name=moore_rees2011>{{citation | first1=Patrick | last1=Moore | first2=Robin | last2=Rees | title=Patrick Moore's Data Book of Astronomy | edition=2nd | publisher=[Cambridge University Press](/source/Cambridge_University_Press) | date=2011 | isbn=978-0-521-89935-2 | page=275 | url=https://books.google.com/books?id=2FNfjWKBZx8C&pg=PA275}}</ref> -->

<ref name="Kronk">{{cite web
  |title=Observing the Ursids
  |publisher=Meteor Showers Online
  |author=Gary W. Kronk
  |author-link=Gary W. Kronk
  |url=http://meteorshowersonline.com/showers/ursids.html
  |archive-url=https://web.archive.org/web/20130724160438/http://meteorshowersonline.com/showers/ursids.html
  |archive-date=2013-07-24
  |url-status=dead
  |access-date=2012-11-17}}</ref>

</references>

== External links ==
* [http://meteorshowersonline.com/showers/ursids.html Gary Kronk's Meteor Showers Online - Ursids]
* [https://web.archive.org/web/20051219053932/http://www.imo.net/calendar/2005/fall International Meteor Organisation Calendar - Fall 2005]
* [http://ursid.seti.org NASA Ursid Airborne Campaign] (2008 + Java applet)
* [http://www5f.biglobe.ne.jp/~hro/Flash/2011/URS/ 2011 Ursids Radio results] (RMOB)
* [http://www.constellation-guide.com/ursids/ Ursids at Constellation Guide]

{{Meteor showers}}

Category:Meteor showers
Category:December

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Adapted from the Wikipedia article [Ursids](https://en.wikipedia.org/wiki/Ursids) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Ursids?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.