Leonids

-”Hello Eric. Here I am!“

- „ Come in, Alice. It´s good to see you. May I help you out of your coat?”

- “ Thanks. Oh, how I like that about elder man… it´s so awfully old-fashioned and charming.”

- “My pleasure, dear. Eldery men, I´ll remember that. Come in. You look tired.”

- “Do I… well, I didn´t sleep much lately. And it´s pretty late, isn´t it?”

- “Yeah, I know. Thanks for coming over. Sit down there, please, make yourself comfortable. I´ll get you a glass of wine, shall I?”

- “No. A strong coffee, please. Thank you. Arghhh Eric!!! I hate that giant snake… why did you place the aquarium in the middle of your living room? Every time I come here, I feel it´s staring at me, as if… and why did you leave the glass slab half-open tonight, are you planning to carry out an experiment on me, or what??”

- “No no no… The animal simply needs some fresh air, scaredy-cat. I´ll shut it if you prefer. There!”

- “Ahh, that is too kind of you… though, how can you speak of `fresh air´… don´t tell me it is a smoker-snake and you share your fags with it, he? But say, what´s up, why did you ask me to come over?”

- “I have something for you.”

- “Great! What is it?”

- “Leonids.

- “Leonids??… But you know I just lost some weight without any effort, and you know I like it like that, so how can you tempt me with Brussel chocolate late at night? That´s not fair!”

- “Not `Leonidas´, silly billy. Leonids.”

- “????”

- “Tonight, tomorrow and Saturday night, we have the chance to be in the middle of a Leonid storm. A wonderful Leonid dust trail. Never heard of Leonids, darling?”

- “No…no. Are they… shiny?”

- “Very shiny!”

- “Are they beautiful??”

- “Breathtakingly!!”

- “Are they… dangerous???”

- “Sometimes.”

- “Tell me more! I´m wide awake now.”

- “Okay.

The Leonids are a profilic meteor shower associated with the comet Tempel-Tuttle. They get their name from the location of their radiant in the constellation Leo: the meteors appear to stream from that point in the sky.”

- “Oh, I see. Leo…`Lion´. I love Lions, I almost called my son Leo; but in 2003, that name was on the top 3 list for boys, so we chose another name for him… that was on the top 5 list in 2004, ha ha. But please, go on?”

- “Are you sure you can concentrate?”

- “Yeah, excuse me. Tell me more, about the Tempel comet, the meteor shower and all that. Someone once compared me to a meteor, and then later to a shooting star. So I´m very interested in the subject, believe me!”

- “Hmmmm. Meteors and shooting stars are sinonyms, dear. However… The meteor shower is visible every year around November 17, plus or minus a week, when the Earth moves through the meteoroid stream of particles left from the passages of the comet. The stream comprises solid particles, known as meteoroids, ejected by the comet as its frozen gases evaporate under the heat of the Sun which begins to warm the comet as it comes within the orbit of Jupiter. A typical particle is no bigger than fine dust. The main source of light for a meteor is caused by the meteoroid ramming air ahead of it as it slams into the Earth´s atmosphere at tremendous speed… 71km/s in the case of the Leonid meteorids.”

- “That´s speedy, indeed. What happens to the cosmic dust particles then?”

- “I´ll explain that in a minute. The tremendous pressures cause the dust spec to suffer compression stress that fragments and atomizes the dust and the resulting spray of microscopic debris collides with individual atoms of the atmosphere which then cool by glowing; not by friction as commonly thought. Larger particles leave a stream of smaller particles and compress larger amount of air and form a `Bolide´ or `Fireball´- which can leave a glowing trail in the atmosphere. Leonids in particular are well know for having such bright meteors… but tell me, who used to compare you to a shooting star?”

- “Oh, never mind. I told you it just happened once, and as you said yourself, the dust atomizes and disappears, so there´s not much left of the particular star, in the end…”

- “No, that´s incorrect. The dust, that is the particles of the trail, disappears, but the parent comet does not. It is very resistant, in fact, and has a considerable potential. It keeps coming back and ejecting. Look at Temple-Tuttle, the parent comet of the Leonid stream. It returns to perihelion every 33 years or so, in fact close to 3 times a century, generating new trails of meteoroids and dust each time.”

- “Why, that´s encouraging to learn. So, when did Tempel-Tuttle start crossing our earthly atmosphere?”

- “Oh, a long time ago. In fact, Leonids have been famous ever since, because their meteor showers, or storms, can be, and have been in a few cases, among the most spectacular. For example spikes in activity in 2004 were associated with streams from passages of the Comet Tempel-Tuttle in 1333 and 1733 because the Earth passed through both paths, as altered by gravitational and radiative forces over the time in between, while spikes in activity in 2001 were due in part to the passage of the comet in 1833. The 1833 storm itself was not due to the recent passage of the comet, but from a direct hit with the recent 1800 passage trail left behind, and the 1966 storm was from the 1988 passage of the comet…”

- “Aha, I see… so the effect is very enduring and long-lasting… revolving, also. And it must have a strong effect on nature and humans, or let´s say, the ones who can perceive it, and don´t ignore it, hasn´t it?”

- “Exactly, my love. I like it when you concentrate. For example, the meteor storm of 1833 was of superlative strength, in excess of a one hundred thousands meteors an hour, over the entire region of North America east of the Rocky Mountains. It was marked by the Native Americans, slaves and owners, and many others. It was, in a word, unignorable. Many thought it was the end of the world… or the beginning of a new age.”

- “Wow!”

- “Do you still mind the comparison with a meteor or shooting star?”

- “No, not any more.”

- “Good.”

- “Eric?”

- “Yep?”

- “When exactly do we have to look out for the Leonids? Tonight, or tomorrow, or…??”

- “Well, this year, on November 19th, the Earth passes very close to the centre of the trail created at the comet´s 1932 return. The calculated peak time of the outburst is 04:45 UT. It will probably not last very long, as meteor activity will rise and fall quite sharply, and so to see it you need to be in the right part of the world, which means west of Europe and west of Africa, and some eastern parts of the Americas. You need it to be night-time, and you need the radiant, that is the point in the constellation Leo where the meteors radiate from, to be above the horizon. This years´ encounter with the 1932 trail will lead to enhanced meteor activity: a nice outburst, but below storm level.”

- “Jesus, Eric… that is once again so amazing. But, oh; it´s already past midnight.I have to leave you now, I have to write something down instantly!”

- “What?? I thought we were about to watch the first night of Leonids together?”

- “Oh, I´m so sorry Eric, but I can´t, unfortunately… I really have to write that Leonid stuff down, I have to share it with someone.”

- “Someone? What Someone?? Why not share it with me now? Alice… don´t tell me that this someone is still that reckless Englishmen who pulled the wool over your eyes, please?”

- “Eric… stop it, please. You know this ain´t true. Between him and me, it´s different... it´s cosmic, I told you!

- “Cosmic, pah! You are too foolish, really. But it´s your life... Do what you must, Alice. And just feel free to come back when you need my help to sweep off the dust in your head!”

********************

Again:
- special thanks to Wikipedia (http://www.wikipedia.org/wiki/Leonids )
Other sources:
- Gary W. Kronk´s Comets & Meteor Showers, The Leonids, 1799 Leonids, http://comets.ansmeteors.org/meteors/showers/leonid1799.html
- Armagh Observatory, Leonid dust trails, http://www.arm.ac.uk/leonid/dustexpl.html