NASA - Home. Astronomy Picture of the Day. Galaxy Zoo. Moon Zoo. Yerkes Observatory - Home. Weekday Tours Visitors may tour Yerkes Observatory weekday mornings or afternoons throughout the year.Weekday Tour Schedule, July 2017 to May 2018:Jul 3 - Sep 1, 2017, 11 am, 12:30 pm and 2 pm, Monday through Friday. Sep 5 - Dec 29, 2017, 12:30 pm and 2 pm, Monday through Friday. Jan 2 - Mar 16, 2018, 2 pm, Monday through Friday. Mar 19 - May 23, 2018, 12:30 pm and 2:00 pm, Monday through Friday.LABOR DAY, Sep 4, 2017, 11 am and 12:30 pm only. PLEASE NOTE: NO DAYTIME TOURS WILL BE OFFERED ON MONDAY, AUG 21, 2017. Stars at Yerkes Observatory.