# So There's a Comet Headed This Way? **URL:** \ **Category:** Factual Questions\ **Created:** [August 20, 2013, 6:09pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730 "2013-08-20T18:09:53Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![HeyHomie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heyhomie/32/207_2.png) [@HeyHomie](https://boards.straightdope.com/u/HeyHomie)\ **Post date:** [August 20, 2013, 6:09pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/1 "2013-08-20T18:09:53Z")
Did I hear correctly, that there’s a comet headed this way later on this winter and that it’s going to be magnificent? If so, can anyone fill me in on the details? Thanks! ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [August 20, 2013, 6:15pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/2 "2013-08-20T18:15:44Z")
Comet [Ison](http://en.wikipedia.org/wiki/C/2012_S1) should be visible to the naked eye between about November 2013 and January 2014. But it looks as though it won’t be as bright as early reports suggested. ---
**Author:** ![HeyHomie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heyhomie/32/207_2.png) [@HeyHomie](https://boards.straightdope.com/u/HeyHomie)\ **Post date:** [August 20, 2013, 6:29pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/3 "2013-08-20T18:29:16Z")
Thank you **Colophon**! ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [August 20, 2013, 6:35pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/4 "2013-08-20T18:35:16Z")
I’m crossing my fingers. Even if it’s not visible during the day (which early reports said it might be), it could still be an awesome sight. ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [August 20, 2013, 8:22pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/5 "2013-08-20T20:22:40Z")
The current predictions still put it about as bright as Venus at its peak, which would nothing to sneeze at! That would make it visible from even the worst light polluted skies. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [August 20, 2013, 8:24pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/6 "2013-08-20T20:24:09Z")
Time to read _Lucifer’s Hammer_ again. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 20, 2013, 11:59pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/7 "2013-08-20T23:59:12Z")
> [@](#): > > The current predictions still put it about as bright as Venus at its peak, which would nothing to sneeze at! That would make it visible from even the worst light polluted skies. One caveat here is that Venus is a very small object in the sky, while a comet would probably cover a larger area, and thus be more diffuse. That can make it stand out considerably less, especially in light-polluted areas. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [August 21, 2013, 12:44am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/8 "2013-08-21T00:44:15Z")
If you want a really awsome comet, be on Mars on the 19th of October next year. [Comet 2013 A1 (Siding Spring)](http://en.wikipedia.org/wiki/C/2013_A1) is going to swing by Mars at a distance of only 123,000 Km. (For reference, our Moon is about 3 times that far from Earth.) There’s a microscopic chance that it’ll actually hit Mars, by the way. ---
**Author:** ![picunurse](https://avatars.discourse-cdn.com/v4/letter/p/7bcc69/32.png) [@picunurse](https://boards.straightdope.com/u/picunurse)\ **Post date:** [August 21, 2013, 1:36am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/9 "2013-08-21T01:36:33Z")
> [@silenus](#): > > Time to read _Lucifer’s Hammer_ again. Great read! ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [August 21, 2013, 1:47am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/10 "2013-08-21T01:47:25Z")
> [@dtilque](#): > > If you want a really awsome comet, be on Mars on the 19th of October next year. [Comet 2013 A1 (Siding Spring)](http://en.wikipedia.org/wiki/C/2013_A1) is going to swing by Mars at a distance of only 123,000 Km. (For reference, our Moon is about 3 times that far from Earth.) There’s a microscopic chance that it’ll actually hit Mars, by the way. Sounds like someone’s going to be dusting off the old Illudium Q -36 Explosive Space Modulator. ---
**Author:** ![74westy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/74westy/32/3950_2.png) [@74westy](https://boards.straightdope.com/u/74westy)\ **Post date:** [August 21, 2013, 6:25pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/11 "2013-08-21T18:25:44Z")
> [@dtilque](#): > > If you want a really awsome comet, be on Mars on the 19th of October next year. [Comet 2013 A1 (Siding Spring)](http://en.wikipedia.org/wiki/C/2013_A1) is going to swing by Mars at a distance of only 123,000 Km. (For reference, our Moon is about 3 times that far from Earth.) There’s a microscopic chance that it’ll actually hit Mars, by the way. Since I’ve actually read Lucifer’s Hammer, I think I’ll make a point of _not_ being on Mars that day. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [August 22, 2013, 12:11am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/12 "2013-08-22T00:11:38Z")
> [@Chronos](#): > > One caveat here is that Venus is a very small object in the sky, while a comet would probably cover a larger area, and thus be more diffuse. That can make it stand out considerably less, especially in light-polluted areas. Well, yeah. Comet magnitudes are for total brightness, but consider that comet Hale-Bopp (or as I call it: the one of the two that _really_ looked liked a comet, compared to Hyakutake) only reached around -1 magnitude. That’s considerably less than Venus, with magnitude of -3 or -4, and yet it was a pretty spectacular thing to see. The problem in my eyes is that ISON is a Sun-grazer. Two things will happen as it passes that close to the Sun. The temperature that the comet will be exposed to is enough to melt iron. That is good, in a way. The faster that comet material is sublimated off the more material there is to reflect Sunlight. The bad news is that close passage is well within the Sun’s Roche Limit. This is the distance inside of which tidal forces will break up a non-rigid body, and comets are non-rigid bodies. My guess is that ISON will break up before aphelion, shortly after passing the Roche limit, and then get its butt roasted, sice the surface to mass ratio will greatly increase after break up. But, given that aphelion passage (around Thanksgiving for the Yanks) will be just marginally visible due to its proximity to the Sun maybe there’ll be something to see. I’m betting on a disappointing break-up. ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [August 22, 2013, 12:12am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/13 "2013-08-22T00:12:45Z")
> [@74westy](#): > > Since I’ve actually read Lucifer’s Hammer, I think I’ll make a point of _not_ being on Mars that day. I can guarantee that I won’t be on Mars that day, or anywhere near Santorini, for that matter. 😉 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 22, 2013, 3:31am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/14 "2013-08-22T03:31:37Z")
> [@](#): > > Well, yeah. Comet magnitudes are for total brightness, but consider that comet Hale-Bopp (or as I call it: the one of the two that really looked liked a comet, compared to Hyakutake) only reached around -1 magnitude. Who, really, that’s all? I would have guessed it was a lot brighter than that-- It certainly looked impressive. And Hyakutake might not have been as nice as Hale-Bopp, but it was still quite easily visible, and had enough shape that it was clear that it was a comet (it looked more like a badminton birdie than like Hale-Bopp’s long streak, though). ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [August 22, 2013, 4:53am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/15 "2013-08-22T04:53:43Z")
Here is a short video of a comet hitting the sun yesterday. > **[A comet dives to its death into an erupting sun: Watch it here](https://www.latimes.com/science/sciencenow/la-sci-sn-sungrazer-comet-20130821-story.html)** > > A sun-grazing comet zoomed a little too close to an erupting sun this week, and you can watch its final moments, right here. ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [August 22, 2013, 9:18am UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/16 "2013-08-22T09:18:59Z")
We had a decent comet this last spring > **[Two good comets in 2013?](https://boards.straightdope.com/sdmb/showthread.php?t=667036)** > > 2013 could be a good year for stargazers. I heard about C/2011 L4 (PANSTARRS) last year. It has the potential to be a bright, easily-visible comet. Just a few hours ago, there’s a report of a new comet: C/2012 S1. The breathless reports are that it... ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 22, 2013, 4:35pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/17 "2013-08-22T16:35:47Z")
Huh, must be a slow news day. Satellites like SOHO catch comets hitting the sun all the friggin’ time, and it doesn’t usually make the news. For anyone watching that, by the way, the coronal mass ejection had nothing to do with the comet, and it was just coincidence that they happened at about the same time. The white circle in the middle of the big black blot is the actual size of the Sun’s surface, so the comet hadn’t even hit yet when the CME erupted. ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [August 22, 2013, 5:51pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/18 "2013-08-22T17:51:25Z")
> [@outlierrn](#): > > We had a decent comet this last spring > > [Two good comets in 2013? - Miscellaneous and Personal Stuff I Must Share - Straight Dope Message Board](http://boards.straightdope.com/sdmb/showthread.php?t=667036) I never managed to spot it. ☹ It was a horizon hugger, lost in the twilight every time I made an effort to look for it (not that I made an extraordinary effort to find it, just from my front yard). Anything that doesn’t require averting the eyes to spot a faint smudge would be awesome. I’m hoping for a nice easy spot like good ol’ Comet Hyakutake from the '90’s which hung out near zenith after sunset for a good while in the crisp wintertime sky. No squinting on the horizon, no getting up at 4am. 🙂 ---
**Author:** ![MonkeyMensch](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@MonkeyMensch](https://boards.straightdope.com/u/MonkeyMensch)\ **Post date:** [August 22, 2013, 7:42pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/19 "2013-08-22T19:42:29Z")
> [@Chronos](#): > > Who, really, that’s all? I would have guessed it was a lot brighter than that-- It certainly looked impressive. > > And Hyakutake might not have been as nice as Hale-Bopp, but it was still quite easily visible, and had enough shape that it was clear that it was a comet (it looked more like a badminton birdie than like Hale-Bopp’s long streak, though). I know what you mean about Hyakutake. I lived in a dark sky region (1 mile outside of town was _ **dark** _) at the time and I was thrilled by it. After being so disappointed by Kohoutek (1973) and Halley (1986) I was happy, as a lifetime astronomer, to finally seeing something really comet-like. Your comparison to a badminton shuttlecock is perfect. I just enjoyed so much Hale-Bopp’s comet-y appearance in the late evening sky, pre-perihelion. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [August 22, 2013, 9:58pm UTC](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730/20 "2013-08-22T21:58:01Z")
> [@MonkeyMensch](#): > > Well, yeah. Comet magnitudes are for total brightness, but consider that comet Hale-Bopp (or as I call it: the one of the two that _really_ looked liked a comet, compared to Hyakutake) only reached around -1 magnitude. That’s considerably less than Venus, with magnitude of -3 or -4, and yet it was a pretty spectacular thing to see. I saw Hale-Bopp from a beach west of Malibu; which is still considerably light polluted if not nearly as bad as most of L.A. County. It was a bit diffuse and faint, perhaps about as prominent as a first magnitude star allowing for the comet’s more diffuse structure. But there was no mistaking it, and it was spectacular enough that I was able to see it without deliberately looking for it. [Next page](https://boards.straightdope.com/t/so-theres-a-comet-headed-this-way/666730.md?page=2)