Leonids Computer Graphics '99
Leonids Computer Graphics '99
Our www site is written in Japanese language, except only this page.
If you read Japanese documents, please see other pages as follows.
- What's about Leonids
- Links(include Leonids special)
■Let's see Leonids through Computer Graphics .
Nagoya City Science Museum has been made various C.G. Movies for education of astronomy on planetarium. We collaborate with Nagoya university and the Institute of Space and Astronautical Science. The name of our group is "the ZAKKYO project". The first work of the ZAKKYO project is "Collision of SL9 comet 1994", the second work is "Saturn ling plane crossing 1995", the third is "Comet Hale-Bopp 1996-7", the forth is "Leonids 1998-9". These pages are also written Japanese language, but you can see some snapshots of them.
Our concept is collaborations different specialities. Nagoya City Science Museum's stuffs are the specialists of social education of astronomy. Nagoya university School of Informatics and Science's stuffs are the specialists of visualization using computer graphics technology. Institute of Space and Astronautical Science's stuff is specialist of orbital calculations.
This C.G. is made from scientific data. In our planetarium, we have used this C.G. and explained about Leonids for more than 50000 peoples (only two months!). Original Leonids C.G. is 640*480 pixels, 30flames per second, thousand colors Quicktime movie with wonderful music made by Toshinori Ohkouchi. If you live near Nagoya City, please come to our planetarium.
NEW ! MPEG version movies are available here
You can find 98version movies here.
■Leonids from space(time mark is Japanese standard time, +9 UT)
Distant view of solar system and orbit of Comet tempel-tuttle(greenish line) Comet tempel-tuttle crosses perherion. The Earth passes the orbit of the comet tempel-tuttle. This scene is leonids day on 1998. The Earth passes the orbit of the comet tempel-tuttle once again in 1999.
Comet tempel-tuttle is far away.The scale is Comet tempel-tuttle's one year path. Near the perherion, comet goes fast. Close up view near the Earth at 11 17 1999 4:00am(JST). You can see Earth crossing meteor particle tube. The particles from right side of the screen flow about 42km per second. The Earth moves about 30km per second from left to right on the screen. Close up view near the Earth at 11 18 1999 4:00am(JST).
Eastern Asia looks to the upper stream of meteor particle flow again.
We wish Leonids meteor shower!
Leonids radiant and the Earth from space. It's radiant is different position to be seen from the Earth. Because the Earth moves about 30km per second around the Sun. This is "space Leonids".
■Computer simulation of meteor particles diffusion from the Comet to space
Yellow disk on right center is the Sun, blue disk moving around the Sun is the Comet tempel-tuttle, white dots are meteor particles discharged from comet nucleus. Number is years from start.
Comets are made by ice and particles of rock material. When comets come close to the Sun, ice melt and particles are discharged. If those particles flow into the Earth's atmosphere, they become meteor. The particle's discharge speed is one thousandth of the comet's orbital speed. On this simulation, we set the particle's speed 12m per second. When the comet close to the Sun(inner Mars orbit), the comet discharge particles to all directions. The result of this simulation shows the particles front of the comet meet the particles rear of it more than 500yesrs.
The faster particles have outer and longer orbit than the comet. So the particles come to periherion after the comet. The slower particles have inner and shorter orbit. So the particles come to periherion before the comet.
In every cycle, the particles spread along the orbit . The scene that comet pass the periherion.
After 500 years, you can see the particles scatterd like a long line. Even if the comet reaches beyond the Jupiter's orbit, the particles exists around the periherion.
■Computer simulation of the Leonids as shooting star.
This is new simulation of the Leonids.
We scatter the particles as some spatial density. The particle comes into the Earth's atmosphere, flashes, and dissappears. We set palameters of each particles as follows.
･flashing-altitude
120km-80km(-3,-2,-1mag.)
110km-80km(0mag.)
100km-80km(1,2,3,4mag)･flashing-time
0.75second, Typical flash pattern of meteor.･brightness
-3 - 4 mag. luminous function is 1.5
we consider the distance from observer to the meteor to know the real brightness for observer.
And only upper 4th magnitude(or 2nd mag.), we draw the meteor on screen.･density of particles and results(hourly rate of allsky)
particles per 100km cube 0.05 0.97 9.6 H.R. under ideal condition
(stars=6th,meteors=4th)500 10000 100000 H.R. under urban condition
(stars=3th,meteors=2nd)150 3000 30000 comparison past leonids 1998 ? 1833 ? 1966 ? Under urban condition, the H.R. decreases 1/3, but only darker meteors cannot be seen. So if we encounter great shower, the urban condition is not so bad.
■The Leonids C.G. Movie
You can find mpeg versions of our C.G. Movie. Original Leonids C.G. is 640*480 pixels, 30flames per second, thousands color Quicktime movie with wonderful music made by Toshinori Ohkouchi. If you live in near Nagoya City, please come to our planetarium.
These MPEG version movies are small samples of our work. Please enjoy.
samples of each scene
Astronomy Section
mailto:astro@ncsm.city.nagoya.jp
