Final answer:
The region of the Sun's atmosphere with a significantly lower density, from where the solar wind escapes into space, is known as the corona.
Step-by-step explanation:
The vast region of the Sun's atmosphere where the density of matter is about 10 times lower than average and gas streams freely into space at high speeds, escaping the Sun completely, is the corona. This outermost layer of the Sun's atmosphere extends so far into space, beyond Earth, that technically, we live within the Sun's atmosphere. The corona is characterized by its very low density and high temperatures, and it is where the solar wind is generated—a stream of charged particles that travels through the solar system.