(CNN) -- Today is one for remembrance and holding your loved ones a little tighter.
There's no way around it. September 11 will always be a difficult day because the memories don't fade.
I'll never forget sitting in myclassroom on that beautiful fall morning. The sky was impossibly blue and the air was crisp. Then, everything changed in an instant and a shadow swallowed the sun. But I also remember how my community came together, the way we supported each other and found ways to help.
As Mister Rogers once said, "When I was a boy and I would see scary things in the news, my mother would say to me, 'Look for the helpers. You will always find people who are helping.'"
People are still doing things to keep the spark of hope alive -- like an astronaut who helped fulfill the dream of a 9/11 victim.
When the time came for veteran NASA astronaut Chris Cassidy to go to space for the third time, he reached out to the National September 11 Memorial & Museum in New York City.
There, he learned the story of Chandler "Chad" Keller, who died when American Airlines Flight 77 crashed into the Pentagon on 9/11. As a child, Keller dreamed of being an astronaut, and he became a propulsion specialist at Boeing.
Forget Jurassic Park -- our oceans would have been a terrifying place 500 million years ago. If you went for an ocean dip, you may have encountered this giant "swimming head," a primitive creature built like an underwater tank.
It had multifaceted eyes, a pineapple slice-shaped mouth and spiny claws beneath its head that acted like a rake for prey. The animal's body had a series of flaps to help it swim. And then there was that large head carapace, or a defensive covering, like the shell of a turtle.
Dubbed Titanokorys gainesi, this primitive arthropod, called a radiodont, was huge compared to other contemporary ocean creatures that were about the size of a pinkie finger.
He said the sassy phrase during a courtship display that involves sound and splashing around. Ripper probably took inspiration directly from his caretaker, considering that he was raised by hand at the Tidbinbilla Nature Reserve, near Canberra, Australia.
We're wondering if he knew how to say "you're despicable" like Daffy Duck.
Watch astronauts Thomas Pesquet and Akihiko Hoshide venture outside the International Space Station for a spacewalk Sunday, starting around 8:30 a.m. ET. And thanks for your spacewalk song suggestions -- we took them to heart and updated our playlist.