There is no specific border between the Earth's atmosphere and space, but in most cases space is beyond 100 kilometers where air rarely exists.

We can "see" an object as the light hits that object and its reflection reaches our eyes. However, space between the stars is almost a vacuum. In other words, there is nothing to reflect the light except for small dust particles. Thus, the light can go through there, but light can not reflect back from the surrounding area and as a result, space looks dark and black.

If a human went out into space without wearing a space suit, since space is almost a vacuum, the liquid in our body and blood will come to a boil, and the functions of various organs in the body will stop, leading to death.

At present, there is no clear answer as there is no scientific or observational proof of aliens. However, there are many scientists who believe in "life in space," and investigations and research are ongoing.

Every year, September 20 is "Sky Day" in Japan.
"Sky Day" originates from "Aviation Day," which was created in 1940. It was established to commemorate the one-hour flight around the sky of Tokyo on September 20, 1911, by the Yamada-model Airship developed by Mr. Inozaburo Yamada.
When World War II ended, the Aviation Day celebration was stopped but it later restarted. In 1992, in commemoration of the 40th anniversary of the resumption of Japanese civil aviation, and with a view to encouraging the public to get a better understanding and awareness of civil airplane operations, Aviation Day was renamed "Sky Day", which sounds much more familiar. In addition, a "Sky Day campaign" (September 20-30) was established starting from Sky Day and many commemorative events related to aviation are held at airports and the other places nationwide.

Every year, September 12 is "Space Day" in Japan.
The year 1992 was designated International Space Year (ISY) to encourage widespread consideration of space and the Earth's environment through international cooperation. "Space Day" was established to commemorate this and September 12, the day when astronaut Mamoru Mohri flew to space aboard the Space Shuttle, was selected from the public's suggestions. (The chosen date also benefited from the fact that '92 and 9/12 can be pronounced the same way ("kyu-ju-ni") in Japanese.)

Starting form ISY, Japan also decided to promote space for the long term and commemorative events for "Space Day" have been held every year since then.
As a part of the commemorative event, JAXA holds "Fureai Festival" and an "Essay/Drawing Contest," and also opens its facilities at centers to the general public.
JAXA also designates the whole month of September as "Space Month" and holds "Space Classes" nationwide.