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.
Many of us, while still in grade school, learned about the staggering distances to planets, stars and galaxies. The sun is approximately 150 million km or 93 million miles away, a distance that is known as the astronomical unit (AU). Venus, our closest neighbor, is 0.72 AU from the sun, while Mars is 1.52 AU from the sun.