Comet 55P Tempel-Tuttle was discovered twice independently

Comet 55P/Tempel-Tuttle

Even though comet 55P/Tempel-Tuttle has an orbital period of about 33 years it has only been recovered five times in the past 630 years. The earliest clearly documented return is that of 1366, with the others being in 1699, 1865, 1965 and 1998. The comet may have been briefly sighted in 1035 (indicative of a possible outburst) and in 1234 and it was conspicuous by its non-recovery in 901 (possibly indicating very low surface activity during that return).

We review the absolute magnitude data for comet 55P /Tempel-Tuttle and find tentative evidence to suggest it underwent an outburst in 1699. If large meteoroids were ejected from the comet during the 1699 outburst numerical integration studies find that they would have been Earth-orbit crossing in 1832 and 1965 – years in which the Leonid shower was rich in bright fireballs. The Earth will also sample 1699 ejected material in November 2001.

Comet 55P/Tempel-Tuttle is a small, faint, and unspectacular comet. It has a highly elliptical orbit around the sun, taking 33 years to complete one orbit. The comet’s nucleus is about 2.24 miles across. It comes as close as 0.98 AU and as far as 19.70 AU from the sun.

55P/Tempel-Tuttle is a Halley-type comet, with a period between 20 and 200 years. It was discovered by Wilhelm Tempel on December 19, 1865, and by Horace Parnell Tuttle on January 6, 1866. 55P/Tempel-Tuttle is the parent comet of the Leonid meteor stream. It has only been observed on a few occasions over the past 600 years. Its most recent apparition was in 1998, when it reached perihelion on February 28.

Discovery

Comet Tempel-Tuttle was discovered twice independently—in 1865 and 1866 by Ernst Tempel and Horace Tuttle, respectively.

Overview

Comet 55P/Tempel-Tuttle is a small comet―its nucleus measures only about 2.24 miles (3.6 kilometers) across. It takes Tempel-Tuttle 33 years to orbit the sun once. Tempel-Tuttle last reached perihelion (closest approach to the sun) in 1998 and will return again in 2031.

The pieces of space debris that interact with our atmosphere to create the Leonids meteor shower originate from Tempel-Tuttle. This usually weak annual meteor shower takes place each November, and peaks mid-month. When comets come around the sun, the dust they emit gradually spreads into a dusty trail around their orbits. Every year the Earth passes through these debris trails, which allows the bits to collide with our atmosphere where they disintegrate to create fiery and colorful streaks in the sky.

Every 33 years, or so, the Leonids meteor shower becomes a meteor storm. A meteor storm―versus a shower―is defined as having at least 1,000 meteors per hour. Viewers in 1966 experienced a spectacular Leonid storm: thousands of meteors per minute fell through Earth’s atmosphere during a 15 minute period. There were so many meteors seen that they appeared to fall like rain. The last Leonid meteor storm took place in 2002.

How Comet 55P/Tempel-Tuttle Got Its Name

Comets are usually named for their discoverer(s) or for the name of the observatory/telescope used in the discovery. Since both Ernst Tempel and Horace Tuttle discovered this comet it is named for them. The letter “P” indicates that Tempel-Tuttle is a periodic comet. Periodic comets have an orbital period of less than 200 years.

Discovery: The comet was independently discovered by Wilhelm Tempel on December 19, 1865, and by Horace Parnell Tuttle on January 6, 1866. Hence, it is named after both of its discoverers.

Orbit: Comet Tempel-Tuttle has a highly elliptical orbit that takes it from just beyond the orbit of Jupiter at its farthest point to within the orbit of Earth at its closest approach to the Sun.

Periodic Comet: It is classified as a periodic comet because it has an orbital period of about 33 years. This means that it returns to the inner solar system approximately every three decades.

Leonid Meteor Shower: The Earth crosses the orbital path of Comet Tempel-Tuttle, and when this happens, the debris left behind by the comet burns up in Earth’s atmosphere, creating the Leonid meteor shower. The Leonids are known for producing bright meteors and occasional meteor storms.

Close Approaches to Earth: The comet’s closest approach to Earth can lead to increased meteor activity during the Leonid meteor shower. These close approaches occur when the comet is in the inner solar system, and its debris intersects Earth’s orbit.

Observations: Scientists and astronomers regularly observe and study Comet Tempel-Tuttle during its perihelion (closest approach to the Sun) to learn more about its composition, activity, and to gather information about the formation and evolution of comets in general.

Comet Tempel-Tuttle’s next perihelion passage is expected around 2031. As always, scientific interest in comets like Tempel-Tuttle contributes to our understanding of the solar system’s early history and the processes that led to the formation of celestial bodies.

We interpret the historical activity of comet 55P/Tempel–Tuttle in terms of the observed characteristics of present-day short period comets. In this respect, it is now realized that such comets are liable to undergo significant outburst and mantle loss events at intervals separated by of order a few hundred years.

On this basis one might well expect comet 55P/Tempel–Tuttle to have undergone several outbursts since its earliest sighing in 1366. The limited absolute magnitude data available for 55P/Tempel–Tuttle is not inconsistent with the suggestion that the comet underwent outbursts during its 1699 and 1865 perihelion returns.

If the outbursts of comet 55P/Tempel–Tuttle are interpreted in terms of mantle loss events then the bright, electrophonic sound producing fireballs reported during the great Leonid meteor storm of 1833 may have been due to the Earth sampling mantle material ejected during the outburst of 1699.

55P/Tempel-Tuttle is a mid-sized comet with a medium-length orbit that is highly inclined to the ecliptic plane of the solar system. NASA JPL has classified 55P/Tempel-Tuttle as a “Near Earth Asteroid” due to its orbit’s proximity to Earth, but it is not considered potentially hazardous because computer simulations have not indicated any imminent likelihood of future collision.

55P/Tempel-Tuttle orbits the sun every 12,100 days (33.13 years), coming as close as 0.98 AU and reaching as far as 19.70 AU from the sun. Its orbit is highly elliptical. 55P/Tempel-Tuttle is about 3.6 kilometers in diameter, making it larger than 99% of asteroids, comparable in size to the island of Manhattan.

Images and Observations
55P/Tempel-Tuttle’s orbit is determined by observations dating back to Dec. 22, 1865. It was last officially observed on July 5, 1998. The IAU Minor Planet Center records 392 observations used to determine its orbit.

Recent observations of an unexpectedly high incidence of bright Leonid meteors about 16 h before the predicted maximum of the main shower are explained by the ejection of dust grains into the 5/14 mean-motion resonance with Jupiter, principally during the perihelion passage of Comet 55P/Tempel—Tuttle in 1333.

The dynamical evolution of resonant grains has the following properties: first, the grains do not spread uniformly around the orbit, but instead librate about a resonance centre within the main stream; secondly, these resonant zones contain a much higher space density of particles than the background stream, with the particle density approaching that of recently ejected cometary grains; thirdly, differential precession between the cometary orbit and the orbits of resonant particles may lead to meteor storms at unexpected times, possibly far removed from that of the normal shower.

The presence of resonant dust grains leads to a complex structure within the Leonid meteoroid stream, and is an important general feature of meteoroid streams associated with Halley-type comets, themselves often trapped for long periods in mean-motion resonances.