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.
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.