“Sky-Is-Falling” Asteroid Flies By

The Earth-crossing asteroid 4179 Toutatis is making one of its close flybys, gliding among the stars and awaiting your telescope. Its magnitude will be 10.9 to 10.5 from December 11th through 11th.

JPL / Steve Ostro
Toutatis Chart
Toutatis is crossing Cetus and Pisces on the evenings of December 11–14 for the time zones of the Americas. The dates here are Universal Time; 0h UT is 7 p.m. on the previous date EST. The black rectangles show the areas covered by the magnified charts below. Click on any chart for a larger version. And here are printable black-&-white charts for use at the telescope.
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Toutatis Chart 1
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Toutatis Chart 2
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Toutatis chart, evening of Dec. 13, 2012 (American time zones)
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Toutatis Chart 4
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In mid-December 2012, a small but famous asteroid makes one of its periodic close passes by Earth. Little 4179 Toutatis is an irregular double lump measuring just 2.8 × 1.5 × 1.2 miles (4.5 × 2.4 × 1.9 km) in size — a largish mountain.

What makes it remarkable is its close passes near us every four years. Astronomers first spotted Toutatis during one of them in 1934 but soon lost it. When it was rediscovered it in 1989, it was named with its possible threat of crashing to Earth in mind. Toutatis was a god of ancient Gaul who’s now best known from the French Astérix le Gaulois cartoons and comic books. In these, the village chief often appeals heavenward to Toutatis to keep the sky from falling, his one great fear. It always works.

Toutatis is in a chaotic 4-year-long orbit that’s currently governed by a 1:4 resonance with Earth and a 3:1 resonance with Jupiter. But the asteroid is tweaked this way and that by its close Earth passes. We’re safe from it for at least the next six centuries, and in the long run, it’s much more likely to be ejected from the solar system than to hit us.

And, no, it won't fall on our heads this month as part of the Mayan calendar end-of-the-world fuss, as some lost souls have been claiming on the internet.

Toutatis passes closest on the night of December 11–12 at a distance of 0.046 astronomical unit (4.3 million miles, 6.9 million km). That's a good 18 times the distance of the Moon. It should then be shining at magnitude 10.9, brightening to a peak of 10.5 four nights later. During that time it’s crossing Cetus and Pisces high in the evening sky.

Our charts here, and our printable black-&-white versions for use with a telescope, plot Toutatis's path for American and European observing hours on those four key nights. The tick marks are labeled with times and dates in Universal Time, so subtract 5 hours to get Eastern Standard Time, 6 hours for Central, 7 for Mountain, and 8 for Pacific. Toutatis will be creeping across the stars at an impressive 20 arcseconds per minute, fast enough for you to see its motion in real time.

Four years ago it didn’t come quite so close. But four years before that (in September 2004) it missed us by just 0.01 a.u., less than a quarter of its distance this time. Its best showing then was for the Southern Hemisphere at 8th magnitude, but many mid-northern observers will remember tracking it low in the south a few days later at magnitude 10.

You can watch the flyby online from the Canary Islands via Slooh (broadcast starts at 5 p.m. EST Dec. 11th), and from the Clay Center Observatory of the Dexter-Southfield School in Brookline, Massachusetts, here:

13 thoughts on ““Sky-Is-Falling” Asteroid Flies By

  1. Tom KelloggTom Kellogg

    This is great timing with the new moon and my planned trip to a dark sky location. I do not see a finder chart attached to the article, am I missing a link or something?

  2. Paul Cox

    We’ll be broadcasting live images of Toutatis in a couple of free public shows on the night of the 11th/12th Dec.

    I’ll be setting up three of the slooh.com robotic telescopes to track the asteroid, including the Half Metre telescope. Details and timings of the shows are on the Slooh homepage.

    The observatory is in the Canary Islands which is 4-7hrs ahead of USA time so the shows are at an ideal time for those who can’t stay up late on a working day. We’ll also broadcast a late show at the time of closest approach (2012-12-12T06:40UTC) with live images from Arizona, together with some popular objects using the Half Metre telescope at the Canary Islands Observatory.

    There are also a couple of other NEOs making their closest approaches a few hours after Toutatis, so we’ll probably track those too.


  3. david

    I am curious, first about the lost souls, and second about other NEA. Is it possible their are others that have" disappeared" or ones that have not been sighted, considering sky watchers can not cover the entire area of space and that during the day it is impossible to view what might be headed this way? Thank you.

  4. weathernaut

    Thanks for the live coverage! I can’t pull Toutatis out of bad light pollution tonight, 11dec12. An earlier start tomorrow will improve my chances. I bagged Ceres and Vesta with my binocs instead for my first views ever. Awesome backup plan, eh?

  5. Eric Holcomb

    Someone please check the declination coordinates on a couple of the Toutatis finder charts including Dec 14 0h UT. It’s showing between 0 and 1 deg, when it should be around +6 to +7 deg. Thanks.

  6. Scott Wlson

    What I would like to see would be an asteroid that makes a close flyby between the Earth and the Moon, and is large enough that A) you could see features naked-eye, or at least with, say, 10x binocs, and B) that you could see moving through space against the background stars in real-time.

    Have any asteroids been discovered that will do this, or are we already aware of any asteroids like this?

    Don’t get mad, but a 10th magnitude object moving five degrees per night just isn’t that interesting.

  7. weathernaut

    Success! Some star hopping from alpha Pisces got me there with binocs and a 9×60 finder on my 12.5" dob @ 25X and 40X. At 3h UTC 13Dec12 Toutatis became indistinguishable from the middle field star in the very small group of three shown along the path here. Great fun!!!

  8. judy

    I am new to any observing. Can you please help me figure out what time and where to look for the asteroid. I live 45 minutes south of cleveland ohio. I can try to find Cetus, but I don’t know any degrees to locate anything. I don’t have a telescope but do have some good binoculars. Thanks for any help at all!!!

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