1. Space debris are artificial objects which goes around the earth without any purpose

2. For example, there is the piece of broken rocket or satellite.

3. They are increasing year by year.

4. The contact with space debris is very dangerous, because they move at about 5 kilometers per second.

5. Space debris have become the environmental problem of space.

6. The environmental problem is serious not only on the earth but in space as well.

Source:http://ja.wikipedia.org/wiki/スペースデブリ

But professor Masatoshi Koshiba observed neutrinos by research conducted at KAMIOKANDE.

KAMIOKANDE is a device to observe the neutrinos.

KAMIOKANDE is located in 1000 meters in the underground. It is a huge water tank, and the water of 300t can be saved.

KAMIOKANDE observes the light caused when a neutrino collide with a water molecule. By observing this light, KAMIOKANDE analyzes where the neutrino come from.

Yoshimasa Takada

Source

http://ja.wikipedia.org/wiki/%E3%82%B9%E3%83%BC%E3%83%91%E3%83%BC%E3%82%AB%E3%83%9F%E3%82%AA%E3%82%AB%E3%83%B3%E3%83%87#_ref-0

Source

http://ja.wikipedia.org/wiki/%E3%82%B9%E3%83%BC%E3%83%91%E3%83%BC%E3%82%AB%E3%83%9F%E3%82%AA%E3%82%AB%E3%83%B3%E3%83%87#_ref-0

2. Comets is similar to a planet away from the sun.

3. But it’s not planet in solar system of the sun.

4. Difference point is that comets have a tail when close enough to the sun.

5. And comets have orbits that are either elliptical or parabolic.

6. Parabolic orbit are called to non-period comets and this comet appears only one time.

http://en.wikipedia.org/wiki/Comet

http://ja.wikipedia.org/wiki/%E5%BD%97%E6%98%9F

Hiroshi Yamaguchi