Celestial navigation Celestial navigation Celestial navigation, also known as astronavigation, is the ancient and modern practice of position fixing that enables a navigator to transition through a space without having to rely on estimated calculations, or dead reckoning, to know their position. Celestial navigation uses "sights", or angular measurements taken between a celestial body (e.g. the Sun, the Moon, a planet, or a star) and the visible horizon. The Sun is most commonly used, but navigators can also use the Moon, a planet, Polaris, or one of 57 other navigational stars whose coordinates are tabulated in the nautical almanac and air almanacs.
Foreign body aspiration x-ray findings that can be seen with foreign body aspiration include obstructive emphysema, atelectasis, and consolidation. While, x-ray can be used to visualize the location and identity of a foreign body, rigid bronchoscopy under general anesthesia is the gold-standard for diagnosis since the foreign body can be visualized and removed with this intervention. Rigid bronchoscopy is indicated when two of the three following criteria are met: report of foreign body aspiration by the patient or a witness, abnormal lung exam findings, or abnormal chest x-ray findings. Treatment of foreign body aspiration is determined by the severity of obstruction of the