Rare opportunity to study planets as Mercury passes Sun

Scientists train telescopes to discover planetary movements as smallest planet in solar system crosses Sun.

Mercury only crosses the Sun 13 times in a century.

So on Monday astronomers aimed their telescopes skywards when Mercury passed directly between the Earth and the Sun.

Scientists have been able to discover the new planets and exoplanets by studying such phenomena.

Al Jazeera’s John Hendren reports from Chicago.