Since 2001, every May 25 fans of Douglas Adams, author of the widely popular five-part trilogy ‘The Hitchhiker’s Guide to the Galaxy,’ celebrate Towel Day. ‘HG2G’ is today’s Throwback Thursday, a look at sci-fi of the past.

This year, people around the world commemorated Adams and his revelation that towels are the most important things one could have when traversing the universe. People proudly carried their towels, shared photos, had contests and paid tribute in many other ways to the author.

In fact, this year’s celebration of Towel Day made it all the way to the International Space Station where Italy’s first woman in space, astronaut Samantha Cristoforetti, read an except from Adams’ book (upside down) and shared the many uses a towel can have aboard the ISS.

Initially a radio broadcast on BBC 4 in 1978, ‘The Hitchhiker’s Guide to the Galaxy’ comes in many incarnations from the widely popular books, stage shows, a TV series, a computer game and the film version released in 2005.

The basic plot of ‘HG2G’ follows the journey of Arthur Dent, an Englishman initially worried about his home getting demolished only to find himself one of the last human beings alive once the Earth is demolished later that day. He is joined by Ford Prefect, a researcher for the guidebook for interstellar travel aptly titled ‘The Hitchhiker’s Guide to the Galaxy.’ This electronic guidebook is ‘the standard repository for all knowledge and wisdom’ providing everything you would need to know when galactic hitchhiking including its famous inscription “Don’t Panic”.

Its comedy is widely important both for being a prime example of sardonic prose and reminding us about the vastness of the universe. As we see scientists such as Neil deGrasse Tyson skyrocket to superstardom, wider audiences become aware of the boundless multiverse and just how insignificant and “mostly harmless” we are. ‘HG2G’ continues to serve as an important reminder of this in an arguably more entertaining way than a television appearance.