International Astronomy Day: Astronomy Quotes That Will Inspire You To Explore The Cosmos 05/15/21 AT 7:50 AM International Astronomy Day is here, so it's the perfect time for astronomy enthusiasts of all ages to enjoy space-related things. International Astronomy Day is actually celebrated twice a year -- once in the spring and then in the fall. The idea is to celebrate the changing constellations and the different things that can be seen in the sky at different times of the year, Days of the Year (DOTY) First started in 1973 by Doug Berger, the president of the Astronomical Association of Northern California at the time, the idea for the occasion is to make space more accessible to everyone and encourage interest in astronomy.