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.
This webpage has an interactive animation that shows how astronomers use stellar parallax to measure how far a star is from Earth. You can click and drag to change the distance of the star from Earth, and see how the star's movement changes compared to distant background objects. (Requires Java.): Herter, T., 2006.