Astronomy Day 2027 is on Saturday

About Astronomy Day

Astronomy Day is a grassroots outreach event. On the day, local groups run public telescope sessions, talks, workshops and hands-on activities, often in busy places such as parks, shopping centers and libraries rather than at remote observatories. Many sites also offer safe, filtered views of the Sun during the daytime. The Astronomical League also promotes an Astronomy Week, running from the Monday before each Astronomy Day to the Sunday after it, for hosts who want more time.

According to the Astronomical League, the day began in California in 1973. Doug Berger, then president of the Astronomical Association of Northern California, decided that instead of asking people to travel to distant observatory open houses, his club would bring portable telescopes to busy urban spots. The approach drew crowds and, the League says, sent many first-time viewers to the club's later observatory events. The League now coordinates the day nationally, publishes a free event handbook with Sky & Telescope, and gives annual awards to the best events.

The date moves every year. The League picks a Saturday near, and usually just after, the first-quarter Moon, when a half-lit Moon is high in the evening sky and easy to show through small telescopes. Since 2007 there have been two dates: a spring Astronomy Day between mid-April and mid-May and a fall one between mid-September and mid-October. Hosts can choose either or both. The League publishes the schedule years in advance; this page follows its list, which currently runs to 2035. Events have been held across the United States and in many other countries.

Sources: Astronomical League: Astronomy Day Fact Sheet, Astronomical League: Astronomy Day website, upcoming dates, Astronomical League: Astronomy Day. How we check dates.

How to mark Astronomy Day

• Look up your local astronomy club, planetarium or science museum and see whether it is hosting a public viewing session.
• Find the Moon in the evening sky and look at it through binoculars, following the line between light and shadow where craters stand out.
• Only look at the Sun through equipment made for solar viewing, such as a properly filtered telescope at a public event or certified eclipse glasses.
• Download a free monthly sky map and try to identify three bright stars or planets from your backyard.
• Take children to a library or museum program on the solar system, or build a scale model of it together.
• Check when the International Space Station will pass over your area and watch for it.

Astronomy Day dates