Starship Asterisk*

Comet McNaught Becoming Visible to the Unaided Eye

Explanation: A new comet is brightening and is now expected to become visible to the unaided eye later this month. C/2009 R1 (McNaught) is already showing an impressive tail and is currently visible through binoculars. The above image, taken yesterday from the Altamira Observatory in the Canary Islands and spanning about five degrees, shows an impressive green coma and a long ion tail in front of distant star trails. Although predicting the brightness of comets is notoriously difficult, current estimates place Comet McNaught as becoming visible to unaided northern hemisphere observers in late June, before sunrise, and in early July, after sunset. Discovered by Robert McNaught last year, the sun-orbiting iceberg will pass the Earth next week and will continue to melt and shed debris as it closes in on the Sun until early July. After reaching about half of the Earth-Sun distance from the Sun, the comet should fade rapidly as it then heads out of the inner Solar System.

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are those dots geostationary sattelites or i had too much ice cold ones ????

The explanation states that Comet McNaught is a "sun-orbiting iceberg", but with an eccentricity of more than 1, this is likely the first time the comet has approached the Sun, and that it will never return. So it is not exactly orbiting the sun.

I was really confused at first because I immediately thought of the 2007 Comet McNaught which was not supposed to return.

OK so I take it that this is a differen't Comet McNaught! http://www.google.com/images?rlz=1T4GZA ... CCkQsAQwAA So the new one is McNaught 2010?

Here--here, lets get ready to celebrate McNaught 2011. We'll put the leftovers of McNaught 2010 back in the cooler to age. What a wonderful tradition to start - EH At least we won't have to bring the ice, it'll be passing by -- right in the sky -- as we all say aye -- lifting the frosty cold ones -- to a great guy -- Andrew McNaught. It kinda brings a tear to your eye.

orin stepanek wrote:OK so I take it that this is a differen't Comet McNaught

Comet McNaught (disambiguation)

verkle2 wrote:The explanation states that Comet McNaught is a "sun-orbiting iceberg", but with an eccentricity of more than 1, this is likely the first time the comet has approached the Sun, and that it will never return. So it is not exactly orbiting the sun.

Not exactly, perhaps, but a hyperbolic orbit is still considered an orbit. In this case, we have an iceberg that has been orbiting the Sun for billions of years, with an eccentricity less than one. It was recently perturbed into a new orbit with an eccentricity of more than one, meaning its velocity is now greater than the solar escape velocity. In principle, an object like this could interact with another planet and even end up in a near circular inner system orbit, although that isn't common.

verkle2 wrote:The explanation states that Comet McNaught is a "sun-orbiting iceberg", but with an eccentricity of more than 1, this is likely the first time the comet has approached the Sun, and that it will never return. So it is not exactly orbiting the sun.

I haven't looked into this comet particularly, but I would be surprised if Comet McNaught's eccentricity is essentially different from one. The comet has effectively "fallen" in a nearly parabolic trajectory from the outer Solar System. I would be very surprised if credible evidence was uncovered that this comet came from outside the Solar System.

I have been asked over email why this APOD linked to a Wikipedia entry that does not, as yet, exist. The link in question is under "Comet McNaught" and points here: http://en.wikipedia.org/wiki/C/2009_R1. So this is a bit of an "experimental" link. It seems likely to me that someone will soon create a Wikipedia entry for this comet, and at that point this link will become more useful. In the meantime, however, the link acts as a bit of request for someone to create a Wikipedia article for (this) Comet McNaught. Can APOD help make Wikipedia more complete, more quickly, by pointing out needed entries? Of course I don't know, but I will be checking to see if anything results, although I may never know APOD's specific influence. - RJN

RJN wrote:I haven't looked into this comet particularly, but I would be surprised if Comet McNaught's eccentricity is essentially different from one. The comet has effectively "fallen" in a nearly parabolic trajectory from the outer Solar System. I would be very surprised if credible evidence was uncovered that this comet came from outside the Solar System.

I don't think there is a suggestion that the comet came from outside the Solar System. It presumably existed as a low eccentricity object far from the Sun until fairly recently, when an interaction with another body put it into a new orbit with an eccentricity very near one. That requires a delta-V of only a few meter per second at Oort cloud distances. It's now in a hyperbolic orbit (e > 1), although just barely. It could have been put into that orbit by the original interaction, or by subsequent perturbations. In any case, unless it gets further perturbed and has a little energy removed, it will leave the Solar System after this pass around the Sun.

RJN wrote:I have been asked over email why this APOD linked to a Wikipedia entry that does not, as yet, exist. The link in question is under "Comet McNaught" and points here: http://en.wikipedia.org/wiki/C/2009_R1. So this is a bit of an "experimental" link. It seems likely to me that someone will soon create a Wikipedia entry for this comet, and at that point this link will become more useful. In the meantime, however, the link acts as a bit of request for someone to create a Wikipedia article for (this) Comet McNaught. Can APOD help make Wikipedia more complete, more quickly, by pointing out needed entries? Of course I don't know, but I will be checking to see if anything results, although I may never know APOD's specific influence. - RJN

It seems a bit dangerous to create a link to an article that doesn't exist. Although it follows the form for similar entries, there is no guarantee that an entry created later will actually have this title (and therefore, this link).

If you want a Wikipedia entry, it is probably best to either create a stub before providing the link (which is very easy), or at least submit a request for an article with this name. For most astronomical topics, an article (or at least a stub) will probably follow very quickly.

Additional images are here.

Chris Peterson wrote: It seems a bit dangerous to create a link to an article that doesn't exist. Although it follows the form for similar entries, there is no guarantee that an entry created later will actually have this title (and therefore, this link).

I followed the suggested link to this comet found on the "Comet McNaught (disambiguation)" page here: http://en.wikipedia.org/wiki/Comet_McNa ... guation%29 . Before I chose that link, I noted that the famously bright Comet McNaught discovered in 2006 correctly redirects from this link: http://en.wikipedia.org/wiki/C/2006_P1 . Still, I frequently make mistakes, and perhaps I should not experiment so much. I don't mean to insult the readers with the link.
- RJN

may be a blessing that Halley only discovered one comet.

ta152h0 wrote:may be a blessing that Halley only discovered one comet.

He did not discover A comet. He predicted one.

Great read Thanks ta152ho

http://en.wikipedia.org/wiki/Halley%27s_Comet

Good job we don't have to name roads after you, like they did with Halley. HuH

Mark

But But But Sir, they named a death star after me,Wolf rayett 104, or is it 194 ?

RJN wrote:I followed the suggested link to this comet found on the "Comet McNaught (disambiguation)" page. Before I chose that link, I noted that the famously bright Comet McNaught discovered in 2006 correctly redirects from this link: C/2006 P1.

Wikipedia links in red are for articles that don't yet exist, such as C/2009 R1.

I know that comets are made of mostly ice, and have been likened to a 'dirty snowball', but since when have they been called 'iceberg'? It doesn't seem to be a particularly fitting or accurate description.

weird, i just got an email telling me i was not authorised toread this forum...

ta152h0 wrote:weird, i just got an email telling me i was not authorised toread this forum...

It's what happens when you follow a link to a message that has been deleted. There was a silly post that got removed a bit earlier.

The above Wikipedia link to this Comet McNaught now contains real content. Retrospectively, it is a good link for the archived APOD, but a strange one when it appeared. I don't know when the C/2009 R1 Wikipedia entry actually first appeared, though. - RJN

The wikipedia article was created on the 8th of June, while the APOD was published on the 7th, linking to the future wiki article. Evidence of time travel?