Dr. Neil deGrasse Tyson is the first to admit that he didn’t get the best grades or SAT scores, but he doesn’t let that stop him as an internationally renowned astrophysicist – and he doesn’t want it to stop the new University of Massachusetts graduates.

“Your grades, whatever is your GPA, rapidly becomes irrelevant,” Tyson said. “Ask anybody just a few years older than you when was the last time someone asked for your GPA, and they will have long forgotten.”

Tyson said other questions, such as those regarding work ethic and effort, matter much more in life.

Tyson’s commencement address lasted for approximately 10 minutes, and his off-the-cuff speech at McGuirk Stadium was filled with anecdotes and humor.

The 56-year-old astrophysicist also told graduates that “it’s okay not to know,” but not to pretend to have knowledge of something.

“If you don’t know, but you think you do know, and you have power over legislation that affects others, that is dangerous,” Tyson said. “That is the sign of the end of an informed democracy.”

He then stressed the importance of science in the world, especially the advances in science that have made Earth – which is constantly trying to kill us, according to Tyson – a more livable place.

“Cavemen had clean air, fresh water. Their food was free range. Yet their life expectancy was 35,” Tyson said. “Something else … improves your health, your wealth, your wellbeing.”

Before the commencement, Tyson seemed excited to give the commencement address to the graduating class.

“My knowledge of this campus goes way back in terms of the quality research that’s done here,” he said.

The astrophysicist added, “[A graduation] is one of the more special moments in a person’s life and to the extent that I can assure that’s the case for this audience, I will do so because I even get misty-eyed every time I attend a graduation.”

UMass system President Robert Caret attended his final UMass Amherst commencement ceremony as he prepares to take on the chancellorship at the University of Maryland. Caret wished the graduates luck, and told them that in a world made ever smaller by technology and globalization, the doors are wide open for them.

“The world is waiting, you are ready for it, good luck as you take the next step in your life journey,” Caret said.

About 5,500 students received bachelor’s degrees at the ceremony, according to a UMass news release. Tyson also received an honorary doctorate degree in science.

“When you leave campus this evening, you will begin an exciting new phase of your life: for college-educated adults, you are fortunate to have many opportunities ahead of you,” Chancellor Kumble Subbaswamy said to the graduates. “And, having seen the class of 2015 in action, I have no doubt you will make good use of these opportunities. … You are smart, resourceful and civic-minded.”

Erin Mabee was chosen as the student speaker, a theater major from Saugus who will serve in City Year Boston in the fall.

Mabee admitted that initially, she didn’t want to attend UMass, but she fell in love with it during her time here. Mabee focused her speech on nostalgia and her experiences at UMass – Avocado Week at the dining halls, 2 a.m. study parties and the October 2011 snowstorm.

“Most college graduates are concerned about what to do for the rest of their lives, but I’m more concerned about not getting Antonio’s on a regular basis,” she said.

The Alumni Association honored ten students at the commencement ceremony as 21st Century Leaders, the most exceptional graduating seniors.

“As students here at UMass Amherst, each one of these young men and women has demonstrated exemplary standards of achievement, initiative and social awareness,” Andrew MacDougall, the president of the Alumni Association said, adding, “These scholars stand before us today as representatives of the qualities that characterize the members of this exemplary class of 2015 and the vast array of opportunities available to all students enrolled at the University of Massachusetts Amherst.”

The University also bestowed Distinguished Achievement Awards on Charles Sherwood, who earned his master’s in 1972 and doctorate in 1977 in polymer science and engineering from UMass, Patricia Crosson, who earned her master’s in 1972 and doctorate in 1974 from UMass’ College of Education, and John Calipari, former head coach of UMass basketball.

The entire commencement ceremony took approximately two hours to complete.

Graduate school marches as well

Additionally, more than 1,700 graduate students were conferred with doctoral and master’s degrees Friday morning in the Mullins Center. A total of 310 doctoral degrees, 1,432 master’s degrees and 47 educational specialist degrees were awarded to graduates of 75 programs, according to a UMass news release. Recipients were as young as 22, and as old as 69.

“Together, you share an understanding amongst yourselves of the commitment and self-discipline that was required to successfully bring you here today,” Subbaswamy told the graduates. “And while you each pursued your own academic focus, you all have a common appreciation for the excitement that comes from following one’s own intellectual interest.”

The University presented Distinguished Graduate Mentor Awards to professor of nutrition Elena Carbone, founding director of the master’s program in architecture and design Kathleen Lugosch, and professor of chemistry Dhandapani Venkataraman. The Distringuished Graduate Staff Award went to Beth Barry of the labor studies program and sociology department, and the Distinguished Graduate Student Teaching Awards were presented to Una Tanovic of comparative literature and Kyla Waters of the sociology department.

Katherine Newman also addressed the degree recipients for the first time as provost and senior vice chancellor for academic affairs.

“Walk to the beat of your own drummer,” she said. “In some ways, your degree is a license to disrupt.”

Patrick Hoff can be reached at [email protected] and followed on Twitter @Hoff_Patrick16.