Continuous positive airway pressure (CPAP) machines are used to maintain an open airway in patients diagnosed with obstructive sleep apnea. The machine functions by blowing pressurized air into the airway via mask at a setting determined by sleep study and prescribed by a physician.
Also the second largest impact structure on Earth, the 1.85 billion years old Sudbury crater in Canada, hosts world-class mineral deposits - in this case nickel-rich minerals that were melted and concentrated by the extreme heating caused by the impact.
And though millionsâin some cases billionsâof years of erosion have made it difficult to determine the exact size of the meteorites, there is a general scientific consensus around the world's largest craters, which mark the largest asteroid impacts. Here are the ten biggest known: 1. Vredefort Crater. Asteroid impact date: Estimated 2 billion years ago. Location: Free State, South Africa. Specs: Also known as the Vredefort Dome, the Vredefort crater has an estimated radius of 118 miles (190 kilometers), making it the world's largest known impact structure.