Fireworks is the highlight of many holidays and celebrations such as Independence Day, Chinese New Year, etc. Though they are older than you thought-it was believed that they were invented in China over thousands of years ago.

A bow is a long and flexible staff with short string attached to the staff's two ends, which is why the staff is bent. An arrow, however, is a shaft with feather-type vanes.

Black holes are one of the most dangerous objects roaming around our universe. These fallen-stars have gravitational fields so strong not even light can escape.