Joseph Ashbrook

Joseph Ashbrook ( born April 4, 1918 in Philadelphia, Pennsylvania; † 4 August 1980) was an American astronomer.

He was a longtime member of the American Association of Variable Star Observers ( AAVSO ). Ashbrook was among the first who studied the Cepheids to determine galactic distances. In addition, he searched old archives by observations of past centuries to the period of rotation of Mars to determine accuracy of a few thousandths of a second.

Ashbrook is the co-discoverer of the periodic comets 47P/Ashbrook-Jackson. The lunar crater Ashbrook and the asteroid ( 2157 ) Ashbrook are named after him.

As editor of the monthly magazine Sky and Telescope, he wrote a regular column under the title Astronomical Scrapbook.