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  • Rapt in Awe

    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.

Let the Year of the Great (maybe) Comets begin!

The year 2013 should bring us two of the most spectacular comets imaginable – two! But . . .

kohoutek

Yeah, I said “maybe ”  and I mean it. I was so proud in November 1973  when my first article for Popular Science magazine appeared with this headline on the cover:

“Get Set for Comet Kohoutek – Sky Spectacular of the Century!”

Well, as you probably know, Comet Kohoutek was the sky dud of the century! So forgive me if this time around I remain just a tad skeptical – call it “cautious” – when it comes to  what could be, for Northern Hemisphere observers,  the two greatest comets of the century – Comet PanSTARRS in March, 2013 and Comet ISON in  December of 2013.

That said, I’m psyched! Comets are the most wondrous – and unpredictable – beasties in the heavenly menagerie. They are full of surprises, beauty, and awe. The great ones dominate the sky presenting easy targets for the newbie and veteran to find and view with nothing but the naked eye, though if you have binoculars, by all means use them. Comets are easy to photograph as well and every viewing will have its unique qualities so I’m sure a lot of cameras, Iphones, and a zillion other imaging gadgets will get a real workout.

Here are the particulars – and while the dates are probably right on, the comet’s performance can be quite different depending – scientists now believe – on its origins.  More on that in a minute.

  • Comet PanSTARRS – look for it March 10-20 low in the West when it may shine as bright as magnitude -2 – that’s almost as bright as Jupiter is right now – which for a comet is very, very bright – brighter than any I’ve seen in the past half century. 
  • Comet ISON – look for it in the morning sky (before dawn, of course) in November and in both the morning and evening sky in December with the most spectacular views (and longest tail) from mid-December t until near Christmas.

That said, do keep in mind that in the final analysis the comet experts can make good forecasts of what to expect – and I respect these – but comets don’t always have the same respect. They carry a great big “your experience may vary” label. They have the ability to totally fool – as Comet Kohoutek did – and they have the ability to gloriously mystify, as Comet Holmes did in 2007. Comet Holmes was discovered in 1892 and had been coming by at roughly seven-year intervals since then with no one but a few comet experts taking notice. Then in October of 2007 without warning it suddenly brightened by a factor of about half a million, became visible to the naked eye, and eventually grew to be the largest – though very tenuous – object in the solar system!

Comet Observing – Your View will differ!

Comets do not streak across the sky, as the name implies. You have plenty of time to see them and they appear to be standing still. But – and this is a big BUT – there will be a great, good, and so-so time to see any comet, so the trick is don’t let opportunity pass you by and don’t expect that if you saw it one day, it will look the same the next. Several factors impact the view of any comet, the most obviously one being local weather.

Comets are at their brightest when near the Sun – but that also makes them difficult or impossible to see. Yes, it’s possible for a comet to be so bright that it is visible in daylight – and that could happen with either of these – but it is not likely. And even when a comet is visible in daylight it may just be for a few hours. The more typical case is a comet is going to be at its best when it’s near the Sun – which means it will be shining in twilight. This will probably be the case with Comet PanSTARRS in March.

panstarrs_3.14

Using Starry Nights sky simulation software I started playing around with different scenarios for this comet based on its predicted path and brightness – and possible tail length.  I found that on March 14 at an hour after sunset – dark enough to see the brighter stars, but not really dark here in Massachusetts – Comet PanSTARRS should be about as bright as the brightest stars and have developed a nice tail.  It will be about 7 degrees above the western horizon and the 3-day-old moon may be close enough (about two fists away) and bright enough to wash out the end of the tail.

Does that mean Match 14 is the only day to see it? Or the best day? Hardly. It may be better several days before or several days after that. The comet will continue to juggle several factors that impact its appearance – it will change in brightness, the tail will change in length, and it will get farther from the Sun each night meaning the sky background will be darker while it is higher – but since it’s getting farther from the Sun it’s also probably getting fainter.

The greatest comet I’ve ever seen was Comet McNaught in 2007. Here’s a picture. Take a look at that fantastic shot.  That’s how it appeared to Southern Hemisphere observers. I was extremely pleased to see it when it was a quite nice comet – but nothing like that. Here’s what I saw and photographed in Westport.

macnaught_me

That should give you an idea of how different the same comet can appear at different times to different observers. That was taken a week before the spectacular pictures linked above – and for several such pictures, go here. Notice that even when at it’s best it is varying from night-to-night.

So will Comet PanSTARRS or ISON look like McNaught? I really don’t know. No one does.  But both are sure going to be fun to watch.

For weekly updates and detailed comet information go here – scroll for PanSTARRS and ISON.

For detailed page with charts, go here – Comet PanSTARRS or go here Comet ISON.

And keep in mind, a bright comet can appear anywhere any time and with little warning. One of the brightest comets of the last century came in 1910 when everyone was reading about – and some were worrying about – the next appearance of Halley’s Comet. But what some folks in South Africa discovered was not Halley’s Comet, but an entirely different one – only at first the professional astronomers thought they were simply mistaken.  To read about this and other very bright comets in history, go here.

So will this year’s comets be spectacular? Wait and see. Hope for the best – but don’t forget Kohoutek – I haven’t 😉

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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