WASHINGTON – There's a rare blue moon tonight, a fitting wink to Neil Armstrong by the cosmic calendar.

Today is the day of a private service for Armstrong, the first man to walk on the moon, who died last Saturday in Ohio at age 82.

A blue moon occurs when there's a second full moon in one calendar month. It won't happen again until July 2015. The full moon cycle is 29.5 days so a blue moon is uncommon and has come to mean something rare. The moon actually won't be colored blue.

Harvard University astronomer Avi Loeb said the moon is far more important to lovers, literature and folklore than to science.

Armstrong's family has suggested paying tribute to him by looking at the moon and giving the astronaut a wink.

Lunar pioneers plan to attend a private service in Ohio for astronaut Neil Armstrong today, following an event to announce a children's health fund in his honor.

Amstrong's family scheduled a private service in Cincinnati. A public memorial service is being planned for early September in Washington, D.C.

Eugene Cernan and James Lovell are expected at the announcement of the Neil Armstrong New Frontiers Initiative at Cincinnati Children's Hospital Medical Center. The family has suggested memorial contributions be made to that fund or two scholarships in Armstrong's name.

Cernan flew two moon missions and is the last man to have walked on the moon. Lovell's four space missions included commanding the harrowing Apollo 13 flight that was recounted in his book and depicted in the popular movie, in which Tom Hanks played Lovell.

A complete list hasn't been released, but other attendees will include Apollo astronaut William Anders and NASA Administrator Charles Bolden.