1) The phenomenon known as "black holes" occurs when matter is crushed into an infinitely small space, creating a gravitational pull so strong that nothing can escape.

2) The Amazon rainforest produces more than 20% of the world's oxygen.

3) Mount Everest, located in the Himalayas, is the highest peak on Earth, with an elevation of 8,848 meters (29,029 feet). It is a popular destination for mountaineers and represents a significant challenge due to its extreme altitude and harsh weather conditions.

4) The Grand Canyon, located in Arizona, United States, is a massive and awe-inspiring natural formation carved by the Colorado River. It is approximately 446 kilometers (277 miles) long, up to 29 kilometers (18 miles) wide, and reaches a depth of over 1.8 kilometers (1.1 miles).