The Apollo 11 astronauts installed the first seismometer on the Moon ; later Apollo crews set up four more. The instruments detected moonquakes, revealed the inner structure of the Moon & counted over 1,700 meteoroid strikes on the lunar surface. #GAM2019 #RandomAstroFact

July brings the 50th anniversary of Apollo 11 . Neil Armstrong & Buzz Aldrin walked on the Moon as Michael Collins orbited above. Lunar rocks they brought back included a new-found mineral called armalcolite, after the first letters of their last names. #GAM2019 #RandomAstroFact

Decades of search failed to confirm that there's a planet around Barnard's star. Now a planet 3 times as massive as Earth & probably rocky is reported . The star is 6 light-years from Earth; the planet's 233-day orbit is the same size as Mercury's. #GAM2019 #RandomAstroFact

A day on Mercury is longer than a year. If there were hotels on the planet, the cost of a night's lodging would probably exceed annual rent. The robotic probe BepiColumbo was launched last year. It will enter orbit around Mercury on 5 December 2025. #GAM2019 #RandomAstroFact

Global Astronomy Month begins today. See planet Mars this week after dusk. It's moving past two star clusters visible to the eye or with binoculars. To one side is the Pleiades (looks like a little dipper); on the other side is the V-shaped Hyades. #GAM2019 #RandomAstroFact