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.
Our Milky Way galaxy of stars is so huge that even at the speed of light it would take 100,000 years to travel across it! The further a star, the fainter it looks. Astronomers use this clue to figure out the distance to very distant stars.