Cool Comet ISON Simulations Help Us Picture Its Upcoming Flyby

A single frame of Comet ISON showing its location relative to the inner planets in early September. Click to watch the full flyby. Credit: INOVE

Visualizing astronomical concepts can make astronomy a real challenge for the beginner. That’s why nice people create simulations to help us understand how objects like comets move and evolve as they fly headlong into the inner solar system.

By clicking and dragging, you can change perspective on the comet. This is an edge-on or side view of Comet ISON approach to the sun. Credit: INOVE

Let’s take a look at C/2012 S1 ISON, the comet currently in the astronomical spotlight. INOVE Space Models has come up with a beautiful, interactive portrayal of ISON as it sweeps in from deep space, swings rapidly around the sun during its closest approach on Nov. 28 and then returns from whence it came.

A view of the solar system looking from below the plane of the planets up in the direction of Earth’s north polar axis. Click to use the solar system simulator. Credit: INOVE

With a click and drag of your mouse you can zoom in, change perspective and see basic information on the planets and comet. I guarantee you’ll get a great feel for ISON’s orbital path in three dimensions and how the comet changes speed as it approaches the sun. When you it loop-de-loops around the sun at perihelion, the comet’s true speed will be around 840,000 mph (1.35 million km/hr). That’s some roller coaster ride.

Simulations of Comet ISON around the time of perihelion or closest approach to the sun. A very curved tail wraps about the comet’s strongly- curved orbital path when near the sun but soon straightens into a long, graceful plume. The blue line points toward the sun. The black line measures 5 degrees. Credit: Uwe Pilz

German astronomer Uwe Pilz has made a series of simulations of Comet ISON’s tail around the time of perihelion based on how dust particles spew from a comet’s nucleus under the influence of sunlight. The images, which I’ve compiled here into a mosaic, show its tail quickly lengthening to 40 degrees or longer in early December.

The latest brightness predictions for Comet ISON according to NASA’s JPL Horizons site puts it at 10th magnitude – small telescope visibility – by mid-October. The naked eye limit won’t be crossed until a month later on Nov. 13-14. Not until a week and a half after that will the comet reach 2nd magnitude, but twilight will greatly interfere with the view. At perihelion the ISON could rival Venus at -4 magnitude, but it will be too close to the sun then to see with the naked eye.

Best views will come in early December when the comet will shine around 2nd magnitude during evening and morning twilight. While the head might be relatively faint, a long tail is expected.

21 Responses

  1. caralex

    Great animation, Bob. Thanks.

    Does the earth pass through the tail at all? It doesn’t seem to, from what I can gather. The doom-and-gloomers are, of course, predicting cyanide poisoning from the micro-dust in the tail. Trying to convince them otherwise is a lost cause, unfortunately!!

    1. astrobob

      We won’t go through the tail but Earth is supposed to pass through some of the comet’s debris after it’s left the vicinity. There might be a few meteors – that would be all.

  2. Edward M. Boll

    I am still believing that there is some potential for the comet to be somewhat visible on Thanksgiving Day and maybe even a little while the next day. Other than Mercury and Venus, comets or small asteroids and the Moon, there is nothing from outer space that I know that comes closer to the Sun than we do. I saw Venus during an annular eclipse in the afternoon and hope to see Mercury during the total eclipse in 2017.

    1. astrobob

      Well, we can only hope. The comet will do what it will do. It could also be fainter than mag. -4 or break up and disintegrate. Remember what happened with Comet Elenin. Despite bright mag. predictions it faded away before anyone with a small scope ever got to see it.

  3. Edward M. Boll

    A brighter than magnitude -6 on Thanksgiving day, through through the next morning is still within the very possible realm despite what some say. I do not think that anyone can be absolutely certain because each comet behaves a little different than the last one. And such a close perihelion adds to that uncertainty.

  4. larsa

    This simulation is absolutely is wonderful! =D I greatly thank the people who took time to make this! Looks like maybe I will get another great comet viewing on my birthday! Years ago I got to see Holmes when it started to get big and my dad taking me out to see it was the greatest birthday present ever next to my total lunar eclipse. I am excited to view the comet in December as well through my binoculars when ISON it at its best, just got a new pair!

  5. Edward O'Reilly

    Bob,here’s some new and interesting Ison news: Seiichi Yoshida,who posts light curves for a whole host of comets on his excellent site,has a new light curve graph for Ison uploaded.It appears to now show a very sharp perihelion peak of -14!! for the comet(likely for several hours on either side of closest approach).When I first looked at it,I wondered if it indeed showed an increase in brightening.Well,on the twitter site,isonupdates,they refer to this new light curve chart as a “nice increase in brightness”.Also,according to the British Astronomical Association,comparing Ison’s magnitude to the stars surrounding it seems to confirm a current mag of +12 for our oncoming visitor. While Ison will no doubt have its share of surprises,things do seem to be trending in a positive direction. – Edward

    1. astrobob

      Hi Edward,
      I see a peak of about -9 mag. tops on Seichi’s site. -14 isn’t shown on his graph. While 12 mag. is in line with JPL estimates I’m still delighted that the comet’s coming along. Thanks for sharing the news.

    1. astrobob

      It will start the month low in the eastern sky at dawn and move more to the northeast as the month goes on.

  6. John

    I live about an hour’s drive east of San Diego, near an old Gold mine town named Julian, which is at 4,000 ft. Can you tell me when would be the best tiime to observe ISON with the naked eye, and where would I look in the night sky? Thank you astrobob, love your rings!

    1. astrobob

      Hi John,
      You’ll have to patient a while longer. Comet ISON won’t become visible with the naked eye until early-mid November. At that time it will be in the southeastern sky at the start of dawn. I plan to make maps for folks to find it closer to that date.

  7. Phil

    Great images showing the path of ISON.

    What are your thoughts about any possible electrical interaction with the sun’s magnetic fields?

    Also, how close will the earth pass to the incoming debris trail in mid-January?


    1. astrobob

      Thanks Phil. Strong gusts of solar wind and coronal mass ejections from the sun can interact with the ionized gas tails in comets, causing kinks to form or pinching the tail off completely. Like a lizard, a new one grows to replace the old. Since these interactions are common in comets I’d guess we might see something similar with ISON as long as it develops a gas tail. Dust tails aren’t affected. The Earth will pass about 2.8 million miles from debris left behind by the comet. I’ve heard we might encounter some debris but the pieces will be so small they’re not expected to produce much of a shower – at least not visible with the eye.

Comments are closed.