Why do astronomers find it difficult to locate extrasolar planets with telescopes

Is there any danger to eating mold?

How does the molecular clock work? a. it analyzes the brain functionality of two different species. b. it examines and compares the physical characteristics of two different species. c. it illustrates relationships between two different species. d. it compares the number of mutations that exist in the dna of two different species.

Which prefix mean under less or below