Astronomical observatories have been available since ancient times, and many cultures set aside special sites for astronomical observations. The thing modern observatories have that was missing from these older observatories until about 1610 was .

telescope

Explanation: Telescope can simply be defined as an optical instrument used to view distant objects. When distant objects are viewed from a telescope, the image becomes magnified. Types of telescope include; optical telescope, infrared telescope, X-ray and ultra-violet telescopes. Astronomical observation has been made before the discovery of the telescope around the year 1610, Astronomical tools in use prior to this time include: astrolabe, nocturnal, the armillary sphere, the cross staff and so on.

answer: b has a great day

explanation: