Assessment 1 of 0

7th Grade Assessment – Unit 4 – RI.7.1, RI.7.2, RI.7.3, RI.7.4, RI.7.5, RI.7.8

Justice February 10, 2015

Read this article. Then answer questions 1 through 7.

Asteroids, Meteoroids, Comets

by Kenneth C. Davis


Where do asteroids like to hang out?

Asteroids, or “minor planets,” can be found all over the solar system, but most orbit the

Sun in an asteroid belt between Mars and Jupiter. Asteroids are space rocks that never

formed into a planet when the solar system was born. This is probably because of the

gravitational effects of Mars and Jupiter. Even if the asteroids had become a planet,

5      it would be less than one-quarter the size of Earth.


How many asteroids are out there?

Astronomers have found more than 20,000 asteroids since 1801 and discover more

every year. The largest asteroid, Ceres, was the first one found. Ceres is almost 600 miles

(970 km) across, or about one-quarter of the size of our Moon. But that’s pretty unusual.

Though a few asteroids are 150 miles (240 km) across or more, most are less than a few

10       miles wide and many are smaller than a car. There are more small asteroids than large

ones because the space rocks often crash into each other and break into smaller pieces.

(The little pieces become meteoroids, some of which are sent on a path toward Earth.)

That’s also why most asteroids are lopsided and full of craters.


The word comet comes from the ancient Greek word kometes, meaning “long-haired.” People thought comets looked like heads with hair streaming out behind them. Comets have long inspired fear and awe because, unlike the predictable Sun, Moon, and stars, they appeared to come and go as they pleased. Ancient people believed the unannounced visitors were warnings of something unusual and terrible—war, flood, death, sickness, or earthquake.


I have a head and a tail. I can move around, but you can’t take me for a walk. What am I?


A comet. Comets are dirty, rocky snowballs

15      that orbit the Sun. They spend most of their

lives far away from us, but when a comet’s

orbit brings it near the Sun, part of its frozen

“head” defrosts into a dusty, gaseous “tail”

millions of miles long. Then the comet appears as a

20      brilliant streak we can see in the sky for

weeks or even months. Since the pressure of

the Sun’s radiation—which is what pushes the

dust and gas away from the comet—always flows

away from the Sun, the comet’s tail always points

25      away from the Sun, too. That means that

sometimes the comet seems to travel backward,

with the tail leading the head!


Where do comets come from?

Most astronomers think that comets come from two places: the Oort Cloud, a huge

icy ring around the edge of the solar system, and the Kuiper Belt, a ring of planetary

30      leftovers inside the Oort Cloud. Comets that come in our direction have probably been

pulled in slowly because of the gravitation tugs of planets or passing stars.

All comets orbit the sun in a predictable period, or amount of time. Short-period

comets orbit at least once every 200 years and probably come from the Kuiper Belt.

Long- period comets take more than 200 years and most likely come from the Oort Cloud.


Edmond Halley (1656–1742)

As a student at Oxford University in England, Edmond Halley (rhymes with valley) was so excited about astronomy that he left school to map the stars in the Southern Hemisphere’s skies. Halley is best known for his groundbreaking work on comets, especially the one that bears his name. Halley was the first to say that comets sighted in 1531, 1607, and 1682 were actually the same comet returning every 76 years. He predicted the comet’s return in 1758, though he knew he wouldn’t live to see the prediction come true. When it did, the comet was named in his honor.

Astronomy was just one of Edmond Halley’s many strengths. Among countless other things, he developed the first weather map and studied Earth’s magnetic field. The multitalented Halley was England’s Astronomer Royal from 1719 until he died in 1742 at Greenwich Observatory in England.



Who’s coming to visit in 2062?

35      Halley’s Comet, the most famous of them all. Halley’s visits have been connected to

several historic events. The Chinese saw the comet in 240 B.C. and blamed it for the death

of an empress. The Romans recorded it in 12 B.C. and thought it was connected to the

death of one of their statesmen. In 1066, the Normans of France believed the comet

marked the invasion of England by William the Conqueror. (The comet is even shown on

40   the Bayeaux Tapestry, which records William’s victory.) Halley’s Comet also came through the

years the famous American writer Samuel Clemens—also known as Mark Twain—was born and died.

8th Grade Math Assessment: 8.F