Category: 5. Life in the Universe

Should We Transmit in Addition to Listening? Our planet has some leakage of radio waves into space, from FM radio, television, military radars, and communication between Earth and our orbiting spacecraft. However, such leakage radiation is still quite weak, and therefore difficult to detect at the distances of the stars, at least with the radio…

Given all the developments discussed in this chapter, it seems likely that life could have developed on many planets around other stars. Even if that life is microbial, we saw that we may soon have ways to search for chemical biosignatures. This search is of fundamental importance for understanding biology, but it does not answer…

Astronomers and planetary scientists continue to search for life in the solar system and the universe at large. In this section, we discuss two kinds of searches. First is the direct exploration of planets within our own solar system, especially Mars and some of the icy moons of the outer solar system. Second is the…

The Building Blocks of Life While no unambiguous evidence for life has yet been found anywhere beyond Earth, life’s chemical building blocks have been detected in a wide range of extraterrestrial environments. Meteorites (which you learned about in Meteorites: Stones From Heaven) have been found to contain two kinds of substances whose chemical structures mark them…