Strong evidence for the existence of planetary systems in the process of formation around other stars comes from:
A) spectroscopic evidence of large quantities of molecules such as ammonia and methane, which can exist only in planetary atmospheres.
B) photographs and infrared observations of disks of dust.
C) detection of very regular pulses of radio energy from some stars.
D) direct photography of actual planets near other stars.

Question

Quizplus · Accepted Answer

Photographs and infrared observations of disks of dust around other stars provide the strongest evidence for the existence of planetary systems in the process of formation. These disks of dust are thought to be the building blocks of planets, and their presence strongly suggests planetary formation. Spectroscopic evidence of molecules in planetary atmospheres and the detection of regular pulses of radio energy from some stars are not necessarily indicative of planetary systems in formation, and direct photography of actual planets is still a relatively rare occurrence.

Strong Evidence for the Existence of Planetary Systems in the Process