| The Leonids |
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Leonid Main
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Observing the Leonids
The point from where the Leonid meteors appear to radiate is located within the constellation Leo and is referred to as the radiant. The radiant is located in the western portion of that constellation in what is commonly referred to as the "sickle" or "backwards question mark." The following charts will help you find it from both the Northern Hemisphere and Southern Hemisphere:
Northern Hemisphere
This represents the view from mid-northern latitudes at about 2:00 a.m. local time around November 19. Because of Earth's rotation, this view will roughly be the same for every mid-northern latitude location in the world. The red line across the bottom of the image represents the horizon. This does not necessarily indicate the time of maximum. For this information, click here. (Image produced by the Author using SkyChart III 3.5 and Adobe Photoshop 5.5.)
Southern Hemisphere
This represents the view from mid-southern latitudes at about 3:00 a.m. local time around November 19. The red line across the bottom of the image represents the horizon. Once again this does not necessarily indicate the time of maximum. For this information, click here. (Image produced by the Author using SkyChart III 3.5 and Adobe Photoshop 5.5.)
To best observe the Leonids wear appropriate clothing for the weather. Lie outside in a reclining lawn chair with your feet pointing towards the east (the general direction of the radiant). Do not look directly at the radiant, but at the area above and around it. The Leonids can be observed into morning twilight. Other minor meteor showers will be going on at the time and stray meteors, more commonly called sporadics, will frequently be seen that do not belong to a meteor shower. When you see a meteor mentally trace it backwards and if you arrive at the "sickle" of Leo it is probably a Leonid.
Information for Advanced Observers
The Radiant
The duration of this meteor shower covers the period of November 13-20. Maximum currently occurs on November 17 (solar longitude=235.3 deg), from an average radiant of RA=153 deg, DEC=+22 deg. Although the maximum hourly rate typically reaches 10-15, this shower is most notable for producing greatly enhanced activity every 33 years---events that are associated with the periodic return of comet Tempel-Tuttle. During these exceptional returns, the Leonids have produced rates of up to several thousand meteors per hour. The Leonids are swift meteors, which are best known for producing many exceptionally bright meteors that leave a high percentage of persistent trains. The radiant's daily motion is +1.0 deg in RA and -0.4 deg in DEC.
The Orbit
The orbit of the Leonid stream, based on the orbits of 12 meteors photographed during the early 1950s and the orbits of 3 meteors detected by radar during the early 1960s, is as follows:
| AOP | AN | i | q | e | a |
|---|---|---|---|---|---|
| 173.1 | 235.4 | 161.0 | 0.983 | 0.901 | 9.956 |
The 1965 orbit of comet Tempel-Tuttle, according to Yeomans' 1981 study published in Icarus is
| AOP | AN | i | q | e | a |
|---|---|---|---|---|---|
| 172.6 | 234.4 | 162.7 | 0.982 | 0.904 | 10.272 |
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