Approach of Asteroid 4179 Toutatis

This article is the first in a series by Prafull Sharma, a student and amateur astronomer based in Delhi, India. He recently discovered a new comet, SOHO 2333, which is a fragment of 96P/Machholz. In addition to the comet, Sharma has discovered 13 asteroids, 87 supernovas, and 55 variable stars. He uses a SkyMaster 25x70 binocular to aid him in his work. Celestron is thrilled to feature Prafull's articles here on our blog!

 On 12th December 2012 at 06:40 UTC, Asteroid 4179 Toutatis made a close pass by the Earth, coming within 6.9 million kilometers (4.3 million miles) of our home. It was shining at magnitude 10.9 that night. Toutatis passed through the constellation Cetus, into constellation Pisces, and then back into constellation Cetus.

Asteroid 4179 Toutatis
A computer-generated view of Toutatis

Toutatis is 2.7 miles (4.46 kilometers) long and 1.5 miles (2.4 kilometers) wide with mass of 5.0×1013 kg. It is one of the largest asteroids that comes near our planet and approaches Earth every four years. Although it is half of the size of the asteroid thought to have wiped out the dinosaurs, Toutatis poses no immediate danger to us. Astronomers have projected its orbit hundreds of years into the future and concluded that there is no risk of Toutatis colliding with Earth. In fact, astronomers believe Toutatis has been passing Earth’s orbit every four years for billions of years. It will likely continue to do so, harmlessly, for billions of years to come.

Toutatis is a well-known asteroid; it has been studied extensively and its orbit has been fully determined. That’s why it has a proper name, instead of just a numerical designation. Toutatis was first observed and cataloged on February 10, 1934, as 1934 CT, but was lost after a short duration in which it couldn’t be observed. The asteroid remained lost for several decades even though it approached Earth every 4 years. Then, on January 4, 1989, Christian Pollas spotted it. Its orbit was then calculated enough that there was no danger of losing sight of it again and finally the International Astronomical Union (IAU) officially named this object after the Celtic god Toutatis (Teutates).


Path of Asteroid 4179 ToutatisToutatis' orbital path. Credit: NASA/JPL

Now, Toutatis is known as one of the largest of the Potentially Hazardous Asteroids (PHAs). Despite this menacing name, the term PHA simply refers to any asteroid that approaches within 4.6 million miles (7.5 million kilometers) of Earth. That’s approximately 19.5 lunar distances, about the distance of Toutatis at this 2012 passage.

Next time Toutatis will approach at least this close to Earth is in November of 2069 when the asteroid will fly by at a distance of only 0.0198 AU (7.7 lunar distances). We’ll be waiting for it!

- Prafull Sharma
Celestron Contributing Blogger