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.
Only around 180 impact craters have ever been discovered on Earth and around 30 per cent of them contain important natural resources of minerals or oil and gas. The largest and oldest known crater prior to this study, the 300 kilometre wide Vredefort crater in South Africa, is 2 billion years in age and heavily eroded.
The second largest crater in the world was formed by the impact of a comet according to a 2014 study by researchers in Canada and Ireland. Colliding with Earth almost 1.85 billion years ago, the estimated diameter of the crater is 81 miles (130 km).