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.
The Sun is 9 feet (2.7 m) across and 1000 feet (300 m) away. Pluto is 7 miles (11 km) away, and the nearest star is still off the real Earth: 49,000 miles (79,000 km) away. If we let the Sun be a quarter, the Earth is a speck 1/100 inch (1/40 cm) in diameter and ten feet (3 m) away. Pluto is more than a football field away: 350 feet (110 m). And at last we can begin to show stars in our scale model. The nearest one is about 500 miles (900 km) away, and it, too, is the size of a quarter, with a pea-sized companion star about 200 feet (60 m) away.