Read Asteroids, Comets, and Meteors. Many people have looked up into the night sky on a starry night and spotted shooting stars. They may ask themselves, what are the different items that soar through our night sky? It's easy to confuse asteroids, comets, and meteors as they share many similarities, but they are actually quite different. Asteroids and meteors take a more circular orbit around the sun. In contrast, a comet's orbit is usually more of an oval pattern. Meteors are what we typically call shooting stars. They are much smaller than asteroids and comets. Meteors are less than ten meters across. Asteroids and comets, on the other hand, can be several kilometers across. Some are even hundreds of kilometers across! Because meteors are so small, they often get pulled into planetary orbits, while asteroids and comets are large enough that they stay within the gravitational pull of the sun. Meteors are small enough that if they begin to hurdle towards the earth, they either burn up in Earth's atmosphere, or hit the earth with very little impact. Several millions of meteors fall towards the earth every year. If an asteroid or comet hit the earth though, they would have a severe impact.

Scientists believe an asteroid the size of San Francisco hit Earth 65 million years ago. It had a huge environmental impact on the earth and caused the extinction of many animals, including the dinosaurs. Asteroids and comets get named, while meteors are too small and plentiful to name. Asteroids are given a name by the person who discovers them. On the contrary, comets are named after the person who discovered them. For example, Guiseppe Piazzi discovered the first asteroid and named it Ceres. Edmund Halley discovered Halley's Comet.

Asteroids and meteors are made of rock and metal. Comets are made of ice, hydrocarbons, and rocks. Comets have a volatile core, while meteors and asteroids do not. Comets can have their own atmospheres, where asteroids and meteors do not. The next time you look up at the night sky, see if you can spot any meteors flashing by. Maybe you will be lucky enough to trace the tail of a passing comet or asteroid instead!

Which information in from the article helps the reader understand the overall text structure? (2 points)

a
The author explains the similarities and differences between asteroids, comets, and meteors that have hit the earth, and the impact each made.

b
The author explains the similarities and differences in characteristics between asteroids, comets, and meteors.

c
The author explains the similarities and differences between people who look in the night sky using a telescope and those who look with their eyes.

d
The author explains the similarities and differences between the size, power, and appearance of asteroids, comets, and meteors.