So the new comet, McNaught, is now very much a naked-eye visible object. Apparently it is the brightest comet in the last 30 years or so. I learned* that (for those in the Northern Hemisphere) Wednesday evening might well be the last chance to see it before it becomes a Southern Hemisphere object. [Update: It seems that it’s still been visible these last few days. Maybe it will be tonight (Saturday).] [Update: See later post here.]
So take a peek outside if you can. It might be a chance in a lifetime!
Have a look at this SkyTonight page for finding instructions. Come back and let us know if you saw it! (If you get a picture, share it with us too! I can post it here for you. The one above, by Gary W. Kronk, is at the gallery at SkyTonight.)
-cvj
*Thanks Amara Graps, and Nick Warner.
I googled whether McNaught was short or long period and discovered this page. When I have time to think I will learn the math that Amara presented. For the moment I am satisfied that the comet is either long period or unbound to the Sun. My guess is that if our planets perturbe McNaught, then the orbit will likely move to greater eccentricity and therefore more likely to be unbound hyperbolic.
I thought I captured the large version, but appararently not. It is here, at the bottom of the page. Just click on the picture.
In addition to that spectacular photo is another photo that is scientifically very interesting. It was taken today from Wellington, Colorado with a wide lens, fast film, and only 20 second exposure. The photographer Daniel Laszlo says:
“A portion of Comet McNaught’s dust tail is still visible in dark Western skies for the Northern Hemisphere Jan 18 UT. Near Boulder CO. torncomet@yahoo.com reported seeing faint streamers after twilight extending from the Zodiacal Light on Tuesday evening after 0000 UT Jan 17. He attributed the sighting to dust shed by Comet McNaught. I was able to confirm his visual description the following night, and the camera captured a 10 by 15 degree swath of tail after twilight. The tail could be found shortly after Venus set. The brighter portions are not difficult in 10×40 binoculars. An observing site dark enough to show Zodiacal light is recommended. The brightest star in the image is Enif. Delphinus is visible to the lower right. Cheers, Dan Laszlo Newsletter Editor Northern Colorado Astronomical Society Fort Collins CO USA 105 W 40.5 N”
That light triangle is the Zodiacal Light, which is the visible part of the interplanetary dust cloud. A debate that has been ongoing since the 1970s in the interplanetary dust community is ‘what is the relative contribution of asteroids and comets to the interplanetary dust cloud?’ So here in this photo, we have both the question and one of the contributors framed in the same photo. If you want to know more about interplanetary dust, I have a readable (I hope) account in my old-ish (but still relevant) article: Dusty Phenomena in the Solar System.
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WOW, that New Zealand shot is *spectacular*! Thanks for the link.
I’m not sure that the “barycentric” value of 1/a is that I used from the MPC was the best number to use; it was a number out of several listed to give its semi-major axis. I’m not a comet dynamicist, but I talked to someone at my institute today who is, and I asked him about comet McNaught’s orbit. He told me that the current orbital values for the comet show an eccentricity of 1.000_something, so then hyperbolic, and therefore the comet won’t be returning. However, its orbit continues to take it through the inner solar system and will be likely perturbed, who knows to what now. So it is possible that it could be perturbed such that the comet will be bound (with an eccentricity of 0.999_something). He said that its ‘revised’ orbit won’t be known for a while (several months, say).
The southern hemisphere folks might have a better ‘comet show’ than the northern hemisphere people, now that it is releasing gas and dust like crazy. Look at this one fantastic view, from New Zealand, for example.
See Amara’s posts above.
-cvj
Can any one tell me the period of this the “McNaught” comet?
Amara -thanks! Everyone…. see the new post.
-cvj
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It’s cloudy all over today, so I cannot try this, but apparently the comet is visible in broad daylight, and with a tail etc. (tipped off by Phil Plait).
On another note it may be of interest, in relation to SOHO and helioseismology, to mention, “Aerogels and Stardust”
As one tends to look at, we should not forget the trail it leaves as well, eh?
Ps.(please delete this part if you feel it appropriate)Hopefully the “no follow” rule is not instituted “here” in asymptotia, as well as, “in cosmic variance.” It may have an effect on what one can see?
Oh, and it’s beautiful… I can see the comet from my terrace in the hills looking towards Rome. It is hanging over the city now, so the view is not missing yet for the Northern Hemisphere people.
You can see the comet saturate the SOHO LASCO C3 detector… Here are movies and explanations.
SOHO is using the comet to measure the solar wind speed close to the Sun, so the comet will act as a probe. Even more interesting is the magnetic properties that the comet will experience when it traverses the north-south heliospheric current sheet of the solar wind/Sun’s magnetic field. The Eureka article said that this is when the ion tail could fragment.
About the tails. In the Earth-based and SOHO photos I’ve only seen the dust tail. But from the STEREO spacecraft, is that structure in the ion tail? The otherwise very descriptive web page doesn’t say. It could be that the dust tail is so bright that is is dominating the seeing of the other tail.
Cynthia: I think the easiest way for you to see the logic, is to set up a “chain” of time equivalences: [tex]\left( {6.965\times 10^{13}\sec } \right)\left( {{{hr} \over {3600\;\sec }}} \right)\left( {{{day} \over {24\;hr}}} \right)\left( {{{yr} \over {365.24\;days}}} \right)
[/tex] Do you see how the units cancel? When you feel comfortable with that, you can multiply the numbers together to get the quickest unit conversion, in this case: 1 year = 3.15567E7 sec. The dimensions for each of the pieces must be the same, which in this case is time to the first power. You can apply this kind of chain of unit conversation for any unit that you see that you can’t grok because it is not in familiar or convenient units.
Amara,
I appreciate you clarifying this issue for me! It appears the root of my problem is that I didn’t have a clues as to how to convert P=6.95E13 sec into years. Thanks for doing it for me.
Have a most enjoyable weekend!
Cynthia
This comet seems to be barely bound to the Sun. I think it must be difficult to know the exact orbit for these Oort Cloud comets because the orbits can change while they are in the ‘inner’ (here I include Jupiter when I say inner) solar system.
For example, Hyakutake’s orbit had a period of 8000 years before it entered the ‘inner’ system, and had an orbit of 14,000 years afterwards. I’m guessing that the numbers given at the MPC are anticipating such an orbital change, because of what is listed at the bottom, where it says:
” The “original” and “future” barycentric values of 1/a are +0.000059 and +0.000518 (+/- 0.000048) AU^-1, respectively. ”
Cythia, here is how you can make the calculations yourself to check out the orbit.
Let’s look at the speed of this comet at perihelion, so at q = 0.17 AU = 2.5432E12 cm. If we take the second value for 1/a, above, then the semimajor axis a = 16,950 AU, which is 2.536E17 cm. What is the eccentricityf? q = a(1-e), so e = (1-q/a). Plugging the numbers in we have eccentricity e = 0.999989971 . I’m sure that’s too many digits for the given uncertainty, but because e>1 means a hyperbolic (unbound) orbit, then we know that this comet is barely bound. This is probably the calculation that Scott H. made already made.
Looking at the velocity. Any orbital velocity is given by:
[tex]v^2=GM_S(1/r – 1/a)[/tex]
So at perihelion, the distance at which the comet is now, roughly, v = 1.085E7 cm/sec or 108 km/sec. It’s cruising! No wonder we have such a short time to see it. The period? Well…
[tex]P = \sqrt {\frac{{4\pi ^2 a^3 }}{{GM_S }}}[/tex]
so that P = 6.95E13 sec = 2.2 million years. (I think I did my algebra right.) I suggest not to wait up for this comet’s return…..!
Tried looking for it at 30 below celsius. To the west? I’ll have to look harder, and dress warmer.
Hello again Scott H.!
Looking at the nomenclature for Comet McNaught, it contains P/ indicating a periodic orbit, instead of a C/ indicating a non-periodic orbit. I truly doubt astronomers would christen McNaught with a “P” rather than a “C”, if they weren’t fully confident that this comet is periodic.
Nevertheless, enjoy the skies, dark or otherwise!
Best,
Cynthia
Caught it from NoCal tonight — quite stunning. At times I could trace the tail out to 1-2 degrees with the naked eye. Hope it’s around for one more look tomorrow!
After all, you seem to be the clear expert, while I’m clearly not…
Well, when it comes to comets I’m definitely not an expert! But I know a bunch about astrophysical systems that involve orbits, so I made some reasonable deductions based on the webpage I found (sparked by your question, which got me wondering what is known about the orbit).
I’m not certain it’s actually classified as periodic — was it described that way somehwere? It seems just as likely, based on the data so far, that it could be on an unbound orbit, in which case it will never come back. (Indeed, that would be consistent with the eccentricity > 1 and negative semi-major axis shown on the JPL page — that’s what happens when you try to fit the parameters of an ellipse to a hyperbolic orbit.)
Hi Scott H., thanks for the link!
I’m still a bit uncertain how a comet can be classified as periodic, when the period is still unknown. In other words, it just doesn’t make sense for a comet, which doesn’t have a known period, not to be regarded as non-periodic. But then–on second thought–I’ll take your word for it. After all, you seem to be the clear expert, while I’m clearly not…
Hi Cynthia, take a look here:
http://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2006+P1&group=com&search=Search
Perihelion passage on the current orbit is pretty well known, and will occur tomorrow (Jan 12). However, the orbit is not sufficiently well modeled to estimate the apohelion passage. The data on the linked page seem to suggest an orbital eccentricity greater than 1 and a negative semimajor axis! My guess is that there just isn’t enough data to get a good orbit model yet.
No doubt it will be quite a while before the comet returns!
Thanks, Clifford as well as Amara and Nick, for introducing me to Comet McNaught! Without trying to sound too corny, you’ve–once again–reminded me that astronomy is a favorite love of mine…
Supposedly, cometary nuclei are highly organic in composition (almost like tar or crude oil), enabling them to be “among the darkest objects in the solar system”. Because the surface of comets contains lots of dark, organic material, this incredibly dark coating permits them to absorb heat rather efficiently. As comets approach the sun, this absorbed heat transforms and ignites, producing outgassing in the form of comas.
Evidently, a comet’s coma is composed of two tails: a “dust” one and a “gas/ion” one. The “dust” tail follows the orbital trajectory, so this tail reflects sunlight. In contrast, the “gas/ion” tail follows the magnetic field lines, hence this tail points away from the Sun.
If I’m not mistaken, McNaught is a long-period comet originating from the Oort cloud, instead of a short-period comet arising from the Kuiper belt.
I’m curious if astronomers have predicted the perihelion passage of McNaught. In other words, I’d like to know if astronomers have set a date for this comet’s return to the inner solar system.
Further, further.
Regarding this post’s title, and a determined effort on my part not to jest, I still intend on being around for quite some time yet 🙂
Never did see the blimmin’ thing despite a concerted effort tonight. Ah well, plenty of comets in the Oort cloud.
Further, and excitingly, the comet will pass through the field of view of SOHO. (http://sohowww.nascom.nasa.gov)
According to their site this will start to happen at 10:00 UT (05:00 EDT) on January 12th.
The comet will be tremendously bright at this point and will probably completely swamp the CCD. It certainly will be the brightest comet ever observed by SOHO!!
I peered in vain but the trees at the back of the garden obscured it. A few degrees further west and all would have been fine. Slightly annoyingly, an astronomer friend phoned up in the middle of all this peering to tell me how excellent the view was!
Incidentally I worked with the discoverer many moons ago. We share first names as well as surnames! It was most confusing for everyone (except us) as there were only the two of us in the department!
Well done Yvette (and excellt joke, andy). Nick Halmagyi and I tried to see it from Griffith Park, from where there is a lot of unobstructed horizon on view, but there were lots of clouds. Oh well.
We looked around the observatory instead.
Cheers,
-cvj
I saw it tonight, and it was stunning because I hadn’t heard a thing about it. What a good habit it is to look up!
The comet is very bright but it’s really hard to get a good view of it; you need a perfectly unobstructed horizon and those are hard to come by.
I looked for the meteor but it was McNaught there.