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Celestial encounter with Comet Catalina during the holidays!

This article appeared in the December 4, 2015 edition of the Davis Enterprise.

Celestial encounter with Comet Catalina during the holidays!

An artist's rendition of a comet from NASA. Image credit: NASA Ames Research Center/K. Jobse, P. Jenniskens.


By Vinita Domier

Special to the Enterprise


Sky watchers can look forward to an astronomical gift this holiday season – but you’d have to rise before the sun to enjoy it. Comet C/2013 US10 Catalina is a sixth magnitude object easily viewable using binoculars or a small telescope in the early hours before sunrise in the constellation of Virgo.


Comet Catalina will be rising higher and growing brighter each morning in December and early January, making it a potential naked eye object in the southeastern predawn sky with a visual magnitude between four and five at its brightest. The next predicted naked eye comet would be another celestial holiday gift - Comet 46P/Wirtanen visible in December 2018 at magnitude three or four.


Even though Comet Catalina will not be very big and bright, it will be easy to locate as it approaches easily identifiable objects in the sky. In the early morning hours of December 7, 2015, Comet Catalina will be in close proximity to Venus and the waning crescent Moon in the Virgo constellation. In the predawn sky of January 1, 2016, Comet Catalina will be in conjunction with the bright star Arcturus in the Bootes constellation.


Comet Catalina, first observed on Oct 31, 2013, is an icy chunk of rock, dust, and frozen gases and water. As it’s orbital period was determined to be around several million years, it is assumed to be a first time visitor to the inner solar system from the Oort Cloud, a spherical shell comprised of millions of icy remnants from the time of planetary formation that envelops the solar system at half the distance to the nearest star, Alpha Centauri.


In its inbound parabolic journey towards the Sun, Comet Catalina gained speed as it approached Jupiter. After its closest approach to Earth on January 17, 2016, Comet Catalina will be on a hyperbolic trajectory that will permanently eject it from the solar system.


When Comet Catalina neared the orbit of Mars in its one and only foray into the solar system, the Sun’s radiation started to sublimate the frozen volatile gases in the comet’s icy core. As the released gaseous and dust particles reflect sunlight, a halo around the comet’s nucleus, known as coma, became discernible.


Around perihelion on November 15, 2015, when the comet was at its closest to the Sun, two tails extending from the comet’s head and pointing away from the Sun also became visible. The relatively straight ion tail comprised mainly of charged gaseous atoms and molecules, is visible due to glowing of the ionized particles, whereas the slightly curved dust tail comprised mainly of dust particles is visible due to the scattering of sunlight by the miniscule particles.


Join the Davis Astronomy Club on Saturday, December 5, 2015, starting at 7pm at the Explorit Science Center (3141 5th Street, Davis) when we will discuss comets in general and Comet Catalina in particular. Everyone is invited to the free meeting indoors, followed by a star party outdoors (weather permitting).



Explorit’s coming events:


  • Explorit’s Exploration Gallery is open to the public every Wednesday, Saturday and Sunday, 1:00-5:00 p.m. and every Friday, 3:00-6:00 p.m.  Admission is $5.00 per person; Explorit members, teachers and children 2 and under are free. Come check out the new Nano Mini Exhibition!
  • Our popular Winter Workshops return for the weeks of Christmas and New Years. Registration is open now! Visit for all the details.
  • Special Introduction to Drone workshop December 21, 22- Call Explorit now!
  • Interested in membership?  Think your Explorit membership may have lapsed?  Call Explorit at 530-756-0191 to check or sign up! Join or renew on or before December 30 to be entered into the prize drawing.


Explorit Science Center is located at 3141 5th St. For more information call (530) 756-0191 or visit, or “like” us on Facebook at

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