NEWSELA Ceres -- Grade 5.pdf

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Ceres is blowing off steam, but why?

By Los Angeles Times, adapted by Newsela staff Jan. 29, 2014 5:00 AM

Dwarf planet Ceres is located in the main asteroid belt, between the orbits of Mars and Jupiter, as illustrated in this artist’s conception. Observations by the Herschel Space Observatory between 2011 and 2013 find that the dwarf planet is shooting steam into space.

LOS ANGELES—It’s hard to say just what Ceres is. It can be thought of as the largest known

asteroid, or as the smallest dwarf planet. For a time in the 1800s, it was considered a full-fledged

planet.

Whatever it is, Ceres is looking more interesting these days. Astronomers, who study space and

planets, have discovered water vapor—like steam—shooting off the mysterious little planetoid. That

discovery could tell us something fascinating about the history of our solar system.

Astronomer Michael Kippers led the study. For the first time, he said, we have “discovered water

in the asteroid belt.”

Ceres sits in the asteroid belt between Mars and Jupiter. That belt may have millions of asteroids

in it, but Ceres is the biggest one and the first one to be discovered. It is 590 miles wide and is round like a planet. Its shape is part of why it was once considered planet-like. It was big enough

for its own gravity to crush it into a round shape.

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are lumpy.

Blasts Of Water Vapor

NASA’s Dawn mission visits Ceres next year. But Kuppers had been looking to do a little advance

scouting before then.

The biggest question hovering around the dwarf planet: Is it filled with water, or not?

Because Ceres isn’t very dense, astronomers think that it could have a large amount of water. If it

did, it would likely be stored away as ice. Astronomers in the 1990s picked up signs of water in the

light coming from Ceres. However, a study in 2011 could not back that claim up.

To settle the matter, Kuppers and his team turned to telescopes at the Herschel Space Observatory.

They spotted clear signs of water coming from two separate dark spots. These were located on

roughly opposite sides of the little world.

Water was coming off Ceres at a quick pace. That made the scientists think there could be a lot of

stored ice. So much, in fact, that once melted, it could add up to more fresh water than we have

on Earth.

The scientists aren’t exactly sure how the ice is stored on Ceres. And they don’t know how it’s

escaping as vapor.

It could be that heat from inside the planet is the cause. This could be making the water rise up

and explode up into blasts of water vapor. It could also simply be that ice on the surface is melting

when the sun hits it. In any case, water on Ceres wouldn’t ever be in liquid form. Liquid water

requires a thicker atmosphere (like Earth’s) to remain stable.

Puzzling Questions Abound

Whatever is going on, the larger question remains: Why is Ceres so wet? And another puzzling

question is why Ceres is so different from the asteroid named Vesta.

After all, Ceres is roughly the same distance from the sun as the lumpy asteroid Vesta. Yet Vesta

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Ceres may have been moved around during a big migration in the solar system’s history. The huge

planet Jupiter, for example, is thought to have traveled long distances: first toward the sun, and

then away from it. Its strong gravity yanked planets and asteroids around the solar system.

The discovery of ice on Ceres also supports the idea that asteroids aren’t as dry as expected, Kuppers said. Comets are icy and are the usual suspects for having brought water to Earth. But,

he said, it could just as well have been an asteroid. Asteroids are basically comets that don’t have

ice. But now one has been found with ice on it.

Answering more questions about Ceres will have to wait. The Herschel telescope, which is still

in space, stopped working last year. But scientists won’t have to wait too long: NASA’s Dawn spacecraft will reach Ceres in spring 2015. It will give scientists a close look at this strange, distant

world.

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Quiz

1. According to the article, why do scientists think Ceres has large amounts of water?

(a) its size

(b) its shape

(c) its density

(d) its atmosphere

2. According to the article, what led to scientists believing that asteroids are not as dry as expected?

(a) the discovery of Vesta

(b) the discovery of Jupiter

(c) the discovery of the asteroid belt

(d) the discovery of water coming from Ceres

3. Select a paragraph from “Puzzling Questions Abound” that contains a word that means “jerked.”

4. Read the sentence from the article.

The discovery of ice on Ceres also supports the idea that asteroids aren’t as dry as expected, Kuppers said.

What is a synonym for the word “expected” as used in the sentence above?

(a) proposed

(b) unwanted

(c) unknown

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Answer Key