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    My Journey through the Astronomical Year

    Think of this as a "companion text" to this, the main web site. Not required reading, butI hope you'll find it interesting and helpful.

Lulin – A visitor from way out – probably (February 2009)

Comet Lulin at closest approach to Earth - 38 million miles - on February 24. (Courtesy NASA/JPL-Caltech.)

Comet Lulin at closest approach to Earth - 38 million miles - on February 24. (Courtesy NASA/JPL-Caltech.)

Let’s start the rumor here – Comet Lulin is really an alien spacecraft making a reconnaisance of our planet.

Not!

But believe me, Comet Lulin’s orbit (see above)  is unusual enough so that I’m sure someone will get that idea.  Like many comet’s, Lulin’s visit is unscheduled and it’s brightness in our skies fairly unpredictable – it may get bright enough to see with the naked eye near the end of this month, but what is more likely is it will remain a  comet only visible in binocular’s and small telescopes and not a very spectacular one at that – but it’s still fun, primarily because of its crazy orbit and the unusual speed at which it will appear to move across our sky.

It does appear to be on a parabolic orbit – meaning it is coming in from “outer space” and making its first visit to our solar system – not that unusual.  What’s unusual are these two things:

  • while a comet can come in from any direction this one is almost on a perfect plane with the orbit of Earth and the other planets of our solar system
  • since its on the plane of the planets, then perhaps it was formed in the same way as the planets as part of the spinning disc of gas and dust that formed the whole system?  Well then, why is it going in the opposite direction? The Earth and other planets are all orbiting the Sun counter-clockwise, Comet Lulin is following a clockwise orbit, so it’s approach to us right now is head on.

That last will make it appear to move quite quickly across our skies – but not streak like a meteor. Folks frequently think comets do move fast, but almost always when we see them they appear not to be moving at all. It is only with careful measurement of their positions against the background stars over a period of hours that we can see they are moving. Lulin will, when closest, appear to be moving so quickly that even with the naked eye the motion of a single night will be obvious.

There is a really cool 3D representation of its orbit on the JPL web site here. Be sure to use all the controls available, including the sliders on the right and bottom of the image.

Circle February 23

So when can you see it and where should you look? Well, my favorite date is February 23 when it is not only about as close to Earth as it will get, but in our sky will be in the same binocular field as Saturn, making it very easy to find. What’s more, that’s near enough to new moon so you don’t have to worry about any interference from moonlight. Now, if the weather cooperates, here’s what we can expect to see.  The following images were taken from Starry Nights Pro astronomy software.

Approximate position of Comet Lulin on evening of February 23, 2009. Red circle is a typical binocular field of view.

Approximate position of Comet Lulin on evening of February 23, 2009 when it will pass close to Saturn. Red circle is a typical binocular field of view.

Approximate position of Comet Lulin on evening of February 24, 2009 as it moves well  past close to Saturn. Red circle is a typical binocular field of view.

Approximate position of Comet Lulin on evening of February 24, 2009 as it moves well past Saturn. Red circle is a typical binocular field of view.

30 EST it should be very close to a 5th magnitude star, 59 Leonis, which makes a good marker to use when judging its movement. Of course, this is based on orbit predictions that may be off a bit, so don't expect to see something exactly like this - but this does capture the kind of motion you can expect around that date.  Also, the tail shown in these images is purely imafinative. Given Lulin's performance to date I doubt that it will show any significant scale. It will probably look like a greenish blob and not too large. But wiat and see - comets are known for their surprises!

Viewed on a typical 8-inch Newtonian scope with a 25mm eyepiece the movement of Comet Lulin can easily be detected over the course of an hour. On February 24 at about 9:30 EST it should be very close to a 5th magnitude star, 59 Leonis, which makes a good marker to use when judging its movement. Of course, this is based on orbit predictions that may be off a bit, so don't expect to see something exactly like this - but this does capture the kind of motion you can expect around that date. Also, the tail shown in these images is purely imaginative. Given Lulin's performance to date I doubt that it will show any significant tail. It will probably look like a greenish blob and not too large. But wait and see - comets are known for their surprises!

More observing highlights:

  • When: Comet Lulin starts in our morning sky. Right now it rises around midnight. By February 24 it will be rising in the east at sunset.
  • Brightness: This is always an educated guess, but right now it is visible in binoculars and small telescopes. By February 24 it may be of naked eye brightness – but just barely. After that it will get dimmer. Most likely. But expect the unexpected.
  • Some special dates:
    • February 5-6 – near Alpha Librae (best seen after midnight)
    • February 23 – near Saturn
    • February 27 – within 1 degree of Regulus
    • March 5 – Near M44 – “Beehive” cluster in Cancer
  • It should remain visible in small telescopes well into May, but will be best seen in late February and early March.

Resources:

JPL 3D graphic of Orbit

Excellent Sky and Telescope article with regular updates and pictures

Spaceweather Comet Lulin Image gallery

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2 Responses

  1. […] For more details and a timetable see my earier post here. […]

  2. […] Last night I got in only half of that before clouds rolled in, but I made up for it by a wonderful two-hour session this morning with some new sights and a couple of surprises. I made a plan the night before to observe Comet Lulin, though I didn’t think it would be too interesting. Then when I got out to the observatory at 3:30 am I realized I had left my notes on Lulin in the house. No problem. A quick scan with the 12X36 binoculars uncovered it  in the southwest where it’s nipping at the tail of Leo. It will overtake the old lion in the next few days, since it’s moving fast. For dates and other information on Lulin see my earlier post here. (And yes, you can see it at a reasonable hour -… […]

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