How many intelligent civilizations should there be in our galaxy right now? In 1961, U.S. astrophysicist Frank Drake, who passed away on September 2 at the age of 92, came up with an equation to estimate this. The Drake equation, dating from a stage in his career when he was "too naive to be nervous" (as he later put it), has become famous and bears his name.

This places Drake in the company of towering physicists with equations named after them including James Clerk Maxwell and Erwin Schrödinger. Unlike those, Drake's equation does not encapsulate a law of nature. Instead it combines some poorly known probabilities into an informed estimate.

Whatever reasonable values you feed into the equation (see image above) it is hard to avoid the conclusion that we shouldn't be alone in the galaxy. Drake remained a proponent and a supporter of the search for extraterrestrial life throughout his days, but has his equation really taught us anything?

Rice is one of the world's staple crops. It is regularly eaten by more than half the world's population. And now, it's been grown in microgravity, on board the newly launched Chinese Wentian space laboratory.

Wentian launched in July and joined up with the Tianhe module of China's new space station. Its original complement of eight experiments included one that attempted to grow rice in microgravity.

Rice typically grows to 3 to 4 feet over four months, and the stalks on Wentian have not been able to complete their entire maturation cycle since the experiment started in July. However, they seem to be on track compared to their Earth-bound counterparts.

There were actually two types of rice launched as part of the experiment. A tall shoot variety reached almost 30 centimeters in the first month of growth, and a dwarf variety reached around 5 cm. Both of these growth amounts are on par for these particular rice varieties on Earth.