Oral route. Many drugs can be administered orally as liquids, capsules, tablets, or chewable tablets. Because the oral route is the most convenient and usually the safest and least expensive, it is the one most often used. However, it has limitations because of the way a drug typically moves through the digestive tract.
Measuring Distances to Stars. Astronomers use several techniques for discovering how far away an object is. The first is called trigonometric parallax and is based on geometry, but it is only good for up to about 500 light-years.
Astronomers also measure distance in the Solar System using a measuring tool called the âastronomical unitâ. 1 astronomical unit, or AU, is the average distance from the Earth to the Sun; thatâs about 150 million km. So, Neptuneâs average distance from the Sun is 30.1 AU. Its perihelion is 29.8 AU, and itâs aphelion is 30.4 AU. We have written many articles about Neptune for Universe Today. Hereâs an article about Neptuneâs moons, and hereâs an article about how Neptuneâs southern pole is the warmest place on the planet.