What is being signaled when you hear 5 short blasts from another vessel’s horn?

Five short blast from another vessel's horn signify DANGER OR DOUBT. When two vessel are about to pass each other by, they have to communicate each other intentions in order to avoid collision. If one of the party does not understand the message that is been relayed or feel that the other party is not taking enough caution to avoid collision, then he should sound the five short blasts to signify that he does not understand what the other party is trying to do. 

It contains only about an eighth of our sun's mass. Faint red Proxima Centauri is only 3,100 Kelvin (5,100 degrees F or 2,800 C) in contrast to 5,778 K for our sun. So Proxima is 500 times less bright than our sun.

Explanation: