"One of the reasons is my sister thinks I'm an alien," Jack writes before revealing the source of his expertise. "Also, I have seen almost all the space and alien movies I can see."
In an interview, Jack told ABC News that he wrote the letter because it thought it would be "really cool" to work for NASA.
"I feel like -- I am the only one who really wants a job at NASA this young," he said.
The position of NASA planetary protection officer pays $124,406 to $187,000 per year, according to the USAJOBS website.
Duties include planning and coordinating activities related to NASA mission planetary protection needs and oversight of their implementation by NASA's space-flight missions.
The recent announcement of the position -- which was created in the 1960s -- has "generated a lot of excitement in the public," NASA said in a statement.
"Although the Planetary Protection Officer position may not be in real-life what the title conjures up, it does play an important role in promoting the responsible exploration of our solar system by preventing microbial contamination of other planets and our own," the statement read.
Dr. James L. Green, director of NASA's Planetary Science Division, promptly responded to Jack's inquiry, writing that the "position is really cool and is very important work."
Green then tells Jack that he hopes he will "study hard and do well in school."
"We are always looking for bright scientists and engineers to help us...." he wrote. "We hope to see you here at NASA one of these days!"
In an email to NASA today, Jack's father, Bryan Davis, wrote that he and his family are "big fans of NASA" and that he posted a photo of his son's letter on Facebook thinking his friends "would get a smile out of it."
"Jack, of course, is pretty sure he’ll get the job," Davis wrote in the email to NASA, which he shared with ABC News. "I’m trying to manage expectations with the hope he might receive a response letter in the mail."
The letter was mailed to the Marshall Space Flight Center in Huntsville, Alabama, Davis said. NASA also called Jack Friday morning to thank him for applying, Davis told ABC News.
ABC News' Jamila Huxtable contributed to this report.