Jeffrey arnett, the psychologist who created the term emerging adulthood, believes that the developmental period between adolescence and adulthood (emerging adulthood):

Jeffery Arnett is a physiologist who coined the term "emerging adulthood." This has previously been known as; delayed adulthood, transition age youth, youthhood, and the twixter years. He believes that the period between adolescence and adulthood is when the person reaches adulthood but doesn't have children, have sufficient funds, or have their own home. He believes it starts at 18 and ends around 25 years of age. He thinks this is when people are still looking for love, make money to spend on recreational activities, and trying to develop their own identities. This theory is highly controversial and has been contested by developmental psychologists. 

1.989×10^30 kg is the weight of the sun.