Comets in the News – Dec 17

The poor weather in AZ and CA have made meteor observing difficult the past few nights. The forecast is for more of the same until at least Friday. In the meantime, this gives me the opportunity to catch up on some comet news.

The past few weeks saw the discovery of 2 new comets and the recovery of a 2 comets on their first return. If you are wondering, Comet Boethin still remains lost (that is if it still exists). For the background story on Boethin, check out the “Where, O Where Has Comet Boethin Gone? : The Case of the Missing Comet” post.

New Discovery – Comet P/2008 X1 (Hill)

Rik Hill of the Catalina Sky Survey used the Catalina 0.68-m Schmidt telescope to discover a comet on 2008 December 4 UT. Comet P/2008 X1 (Hill) is a Jupiter family short-period comet which takes ~6.8 years to orbit the Sun. This is Rik’s 6th comet discovery this year and his 13th overall.

The comet is currently located at opposition in the constellation of Orion. Even though perihelion is not till next May 11, the comet will fade from its current 17th magnitude as it moves away from the Earth. Due to its faintness, the comet can only be observed with astronomical CCD cameras.

Orbit and location of Comet P/2008 X1 (Hill) and the planets on 2008 December 9. Orbit diagram created by 'C2A for Windows' (

New Discovery – Comet C/2008 X3 (LINEAR)

The LINEAR (Lincoln Laboratory Near Earth Asteroid Research) survey discovered its 186th comet on 2008 December 4 UT. The faint 17th magnitude comet was found in the constellation Virgo. The comet, designated C/2008 X3 (LINEAR), is a long-period comet having passed perihelion back on October 11. With an inclination of 66 degrees, the comet’s orbit is almost perpendicular to the orbits of the planets. As can be seen in the orbit diagram below, the comet is currently heading south through the plane of the ecliptic. Similar to the Comet Hill, Comet LINEAR is currently at its brightest and will only be observable with a CCD camera.

Orbit and location of Comet P/2008 X3 (LINEAR) and the planets on 2008 December 9. Orbit diagram created by 'C2A for Windows' (

Recovery – Comet 209P/LINEAR = P/2004 CB = P/2008 X2

Gary Hug of Scranton, Kansas recovered comet P/2004 CB (LINEAR) on the nights of 2008 December 4 and 5 UT. Gary used a 0.56-m reflector to find the very faint 19th magnitude comet. This Comet LINEAR is a Jupiter family short-period comet on a ~5 year orbit.

P/2004 CB (LINEAR) was discovered by the LINEAR survey back on 2004 February 3 UT. After recovery, the comet is given a new designation, in this case, P/2008 X2 (LINEAR). Since the comet has been observed at two separate returns, it will be numbered and become officially known as Comet 209P/LINEAR. At this point the designation/name changing stops and the comet will go by 209P/LINEAR from now on.

On this return, the comet should brighten to magnitude 15 as it approaches perihelion on 2009 April 15 at 0.91 AU from the Sun. Since 1 AU is the average distance between the Earth and the Sun, Comet LINEAR will be closer to the Sun than the Earth ever gets.

Things will get real interesting when the comet makes its next perihelion passage in 2014. The comet will approach within 0.055 AU (5.1 million miles or 8.2 million km) of the Earth on 2014 May 29 UT. Unfortunately, this is an intrinsically faint comet and may not even get bright enough to be seen in large backyard telescopes without CCD imagers.

Luckily, you may not need a telescope at all to see pieces of this comet. According to predictions by Esko Lyytinen published in Peter Jennisken’s book “Meteor Showers and Their Parent Comets”, a new meteor shower may be visible on the night of 2014 May 24. On that night, the Earth will encounter dust released by 209P/LINEAR during the 1800s and 1900s. How many meteors will be seen is unknown, though the calculations by Lyytinen suggest a dozen or more meteors per hour.

Orbit and location of Comet P/2008 X2 (LINEAR) and the planets on 2008 December 9. Orbit diagram created by 'C2A for Windows' (

Recovery of Comet 210P/Christensen = P/2003 K2 = P/2008 X4

The return of this comet was mentioned in the “In The Sky This Month – December 2008″ posting. From that posting…

Yet another comet discovered by Eric Christensen may be visible in backyard scopes in December. This comet is a short-period comet with a period of 5.7 years. It is very faint except when close to the Sun. With perihelion predicted for 2009 January 8 at a distance of 0.53 AU from the Sun, the comet may be bright enough for backyard observers by the end of the month.

There are a lot of question marks about this comet. It was only observed for 1 month in 2003 and those observations were made after perihelion. The comet has yet to be observed during this return and its exact location is unknown. Plus since the comet has never been observed before perihelion we don’t know how bright it should be. Hopefully the comet will be picked up in the next few weeks. When/if that happens, we’ll have a better idea of how observable it will be.

Alan Watson found Comet 210P/Christensen on images taken by the STEREO-B spacecraft on 2008 December 8 and 9. At the time, he thought the comet might be new until Maik Meyer suggested the STEREO comet was actually Comet 210P/Christensen. STEREO (which stands for Solar TErrestrial RElations Observatory) is a NASA mission to study the Sun and its immediate environment. Though not designed specifically to observe comets, its cameras have the ability to pick up bright comets close to the Sun. Quite often, these comets are too close to the Sun to be seen from Earth due to the scattering of sunlight by Earth’s atmosphere.

Based on these new observations of Comet 210P/Christensen, perihelion (or closest approach to the Sun) will happen on 2008 December 19 which is 22 days earlier than predicted. For the next few weeks the comet will be too close to the Sun to be seen by anyone but STEREO and another solar spacecraft named SOHO (SOlar and Heliospheric Observatory). Luckily, these missions make their images available in near-real time allowing us to watch from our computers. From December 21-26, the comet will be visible passing very close to the Sun in images taken by the LASCO instrument on SOHO. I’ll post some pictures when the comet become visible.

In the meantime, you can look at the current SOHO LASCO C3 images here and the LASCO C2 images here. To help you get your bearings, the images are pointed at the Sun. In order to keep the Sun from blinding the camera, it is blocked by a disk (the small circle in the middle, you can also see the arm which holds the blocking disk extending from the middle of the image to the upper right edge).

Orbit and location of Comet P/2008 X2 (LINEAR) and the planets on 2008 December 16. Orbit diagram created by 'C2A for Windows' (


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