Comet Tempel-Tuttle: Parent of a Meteor Shower

The streak of a Leonid Meteor as seen by an observer at the Atacama Large Millimeter Array in Chile. European Southern Observatory/C. Malin.

Each year Earth passes through the remains of comets left behind as these dusty iceballs pass around the Sun. The bits of debris they shed as they race through space form trails of material, and eventually Earth plows through those trails. The bits of rock and dust slide into our atmosphere and vaporize, creating meteors. If there are a lot of them, astronomers call the numerous meteors a "meteor shower." One of the most famous is the Leonid shower, which occurs each November. We see it thanks to a comet that visits the inner solar system once every generation. 

The Cometary Origin of the Leonid Meteor Shower

The comet 55P/Tempel-Tuttle has a very close relationship with Earth. It's not a bright, fabulous-looking one, and has only been observed only during a few of its orbits over the past 600 years. However, it has an interesting effect that you can watch every November and we see it thanks to a comet.

The comet's path around the Sun makes a relatively close approach to Earth every few passes. As it travels, it leaves behind a stream of debris. The "cometary litter" path is fairly dense in some places and more sparse in others. Earth plows through the dense parts each November as it orbits the Sun. The bits of debris get swept up into our atmosphere, where some of it vaporizes, while a few small pieces might make it to the surface. We see that debris in our nighttime skies as the ​Leonid meteor shower, which occurs every November around the 18th of the month. About the only way to get any closer to a comet is to send a spacecraft, which astronomers did with the Rosetta mission to Comet 67P/Churyumov-Gerasimenko. It gave even more insight into the ices and dust that make up comets.

Observing Comet Tempel-Tuttle

Comet 55P/Tempel-Tuttle is relatively dim but can be observed by amateurs with good telescopes. It's often studied by professional observers, and of course, the Leonid shower gives everyone a chance to see tiny bits of this comet fall through Earth's atmosphere as vaporizing meteors. Like other comets, it is a mixture of ices and bits of rock and dust. Its surface has a frozen crust and occasionally jets of material come from inside the comet. The ices sublimate (vaporize) as the comet passes close to the Sun, and the vapor carries dust along with it. This is what forms the path of debris that causes the Leonid meteor shower. Those bits of ice and dust are as old as the solar system, and so when you see one vaporize in the atmosphere, you're seeing a bit of solar system history go up in smoke.

Discovering and Charting the Comet's Path

Comet 55P/Tempel-Tuttle was first observed and noted by Gottfried Kirch in 1699, it was not recognized as a periodic comet at the time. It was also independently discovered on December 19th, 1865 by Ernst Wilhelm Liebrecht Tempel in Marseilles, France, and Horace Parnell Tuttle of Harvard College Observatory, Cambridge, Massachusetts, the U.S. on January 6th, 1866. It is named for these last two observers.  

The comet's orbit takes it around the Sun once every 33 years. At its most distant, the comet travels out about 19 astronomical units (almost out to the average orbital distance of the planet Neptune). Its closest point is about 1 astronomical unit (the same as the distance between Earth and the Sun). 

The Men Who Discovered 55P/Tempel-Tuttle

Ernst Wilhelm Liebrecht Tempel was born in 1821 in Nieder-Kunersdorf, in Saxony. Although he worked as a lithographer, astronomy was his hobby. Using a 4-inch refractor on a balcony of a Venetian palace, he discovered his first comet in 1859. That same year, he became the first observer to note the nebula around the star Merope in the Pleiades. His early discoveries allowed him to obtained employment at the observatory in Marseilles, France in 1860 where he discovered eight more comets, including Tempel-Tuttle.

Eleven years later, Tempel accepted a position as an assistant to Schiaparelli at the Brera Observatory in Milan, Italy. He discovered three more comets there before moving to the Arcetri Observatory in Florence in 1874, where he had access to larger telescopes. There he made his final discovery of a comet, bringing his total to 13. He died in 1889.

Horace Parnell Tuttle was born on March 24, 1839. As an assistant astronomer at the Harvard College Observatory, he spotted his first comet in 1857, which turned out to be periodic Comet Brorsen. The following year, he made a first discovery of Comet 1858 I, now called periodic Comet Tuttle.

Tuttle left Harvard to serve in the infantry during the U.S. Civil War, later transferring to the Navy. During the day he was a Navy paymaster, but at night, he worked at his real love, searching the night skies for comets. During his life, he eventually made a total of four comet discoveries and nine co-discoveries. Besides Tempel-Tuttle, he had earlier been a co-discoverer of Swift-Tuttle in 1862.

After leaving the Navy, Horace Parnell Tuttle worked with the U.S. Geological Survey. He died in 1923 and is buried in an unmarked grave at the Oakwood Cemetery in Falls Church, Virginia.


Edited and updated by Carolyn Collins Petersen