Recently, Astronomers have observed an exoplanet (planet which orbits a star outside the solar system) named Wasp-76b where they suspect it rains iron instead of water.  

• Wasp-76b is an exoplanet that is twice the width of our Jupiter. Its name comes from the UK-led Wasp telescope system that detected it four years ago.  
• It is 640 light-years from the Earth and is so close to its star that it takes just 43 hours to complete one revolution.  
• According to researchers, the iron rain happens because the exoplanet always presents the same face to the star which is called as tidally locked.  
• Earth’s Moon also does exactly the same thing as we only ever see one side. 

Source: ForumIAS factly