Stephen P. Maran

Here are some favorite facts about astronomy and, in particular, Earth and its solar system. With the following information under your belt, you may be ready to handle the astronomy questions on television quiz shows and inquiries from friends and family. You have tiny meteorites in your hair Micrometeorites, tiny particles from space visible only through microscopes, are constantly raining down on Earth.

Astronomy is the study of the sky, the science of cosmic objects and celestial happenings, and the investigation of the nature of the universe you live in. Professional astronomers carry out the business of astronomy by observing with telescopes that capture visible light from the stars or by tuning in to radio waves that come from space.

Telescope motels are establishments where the attractions are the dark skies and the opportunity to set up your own telescope in an excellent viewing location. They usually have telescopes of their own that you can use, perhaps at an additional fee. If you fancy enjoying a stargazing vacation without lugging your own equipment across the country or the world, telescope motels are a good option.

A comet is a stuck-together mixture of ice, frozen gases (such as the ices of carbon monoxide and carbon dioxide), and solid particles — the dust or "dirt" shown here. Historically, astronomers described comets as having a head and tail or tails, but with additional research, they've been able to clarify the nature of a comet's structure.

Normally, only a few meteors per hour are visible — more after midnight than before and (for observers in the Northern Hemisphere) more in the fall than in the spring. But on certain occasions every year, you may see 10, 20, or even 50 or more meteors per hour in a dark, moonless sky far from city lights. Such an event is a meteor shower, when Earth passes through a great ring of billions of meteoroids that runs all the way around the orbit of the comet that shed them.

Hundreds of operating satellites are orbiting Earth, along with thousands of pieces of orbiting space junk — nonfunctional satellites, upper stages from satellite launch rockets, pieces of broken and even exploded satellites, and tiny paint flakes from satellites and rockets.You may be able to glimpse the reflected light from any of the larger satellites and space junk, and powerful defense radar can track even very small pieces.

Digital cameras are now the preferred tools for photographing meteors. But digital meteor photography requires a digital single lens reflex camera (DSLR), which is an expensive camera (point-and-shoot cameras and cellphone cameras don't work very well, except in the rare case when you can catch a brilliant fireball) and a lot of trial-and-error experimenting until you get it right.

When you're outdoors on a dark night and see a "shooting star" (the flash of light from a random, falling meteoroid), what you're probably seeing is a sporadic meteor. But if many meteors appear, all seeming to come from the same place among the stars, you're witnessing a meteor shower. Meteor showers are among the most enjoyable sights in the heavens.

If you're just starting to become interested in astronomy, get into the astronomy hobby gradually, investing as little money as possible until you're sure about what you want to do. Here's a plan for acquiring both basic skills and the needed equipment: If you have a late-model computer, invest in a free or inexpensive planetarium program.