Leonids:
Frequently Asked Questions
What causes the meteors?
Meteors are created when the Earth intercepts a "tube" of dust particles in space. As a comet travels around the Sun, it leaves behind a trail of dust. If the Earth encounters this trail of dust, a meteor shower results. The Leonid meteor shower is the result of the Earth passing through the dust trail left by comet Tempel-Tuttle.
Why are the Leonids more intense some years than in other years?
Tempel-Tuttle orbits the Sun once every 33 years and last came by in February of 1998. Each time it passes close to the Sun it leaves a fresh trail of dust debris. Over centuries the dust trail will disperse and become part of the general Leonid shower. However, close to the comet, the dust will naturally be denser than in the rest of the debris ring, which actually consists of multiple dust trails, one for each of the last several comet passages (i.e., a 1966 dust trail, a 1933 dust trail, an 1899 dust trail). If the Earth intercepts one of the denser regions of the dust trail, a more intense meteor shower results.
In 1998, the most spectacular activity occurred about a day earlier than expected. What happened?
In 1998, two peaks occurred. The first (and best looking) was about a day earlier than expected while the second peak was right on time with scientific predictions. The first peak had large meteor streaks (indicating larger dust particles) that were rather impressive. Studies have shown that this was the result of the dust trail created by the comet in 1899. The second peak was caused by the dust trail from the 1966 passage of the comet. The 1899 dust trail consisted of larger particles (the smaller particles had time to disperse), which caused the larger meteor streaks.
Do the meteor showers present a danger to us on Earth? To airplanes?
No. The very small size of the dust particles stops them from getting very far into the Earth's atmosphere. If you go to the beach or to your backyard and pick up a handful of loose sand or dirt, then the smallest particle your eye can see is about the size of the largest Leonid particle. When these small particles impact the Earth's atmosphere at such high velocities (about 43 miles per second), they create a ball of high-energy plasma that is about 1 yard across. As the particle disintegrates, the plasma dissipates until nothing remains. The plasma ball is what causes the meteor streak that observers on the Earth see. Because of the small size of the particles, they will all burn up at very high altitudes and will not reach either airplane altitudes or the surface of the Earth.
Do the meteor showers present a danger to satellites?
The Leonid meteor storm does represent a threat to satellites. While no major damage to satellites has been reported as a result of the Leonids so far, many agencies that manage and control satellites are actively assessing the threat and taking appropriate actions when possible.
Will the Leonids affect the weather?
No. Since the dust particles burn up at such high altitudes, the meteors will have no impact on the Earth's weather.
