1) Orchids are one of the largest families of flowering plants, with over 25,000 species.

2) Michael Phelps, an American swimmer, has won a total of 28 Olympic medals, including 23 gold medals, making him the most decorated Olympian of all time.

3) The Earth's core is hotter than the surface of the Sun.

4) The Sahara Desert, located in North Africa, is the largest hot desert in the world, covering an area of about 9.2 million square kilometers (3.6 million square miles). It is characterized by vast stretches of sand dunes, rocky plateaus, and extreme temperatures.