"Planet Nine": Have astronomers found a huge new world past Pluto?

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1 "Planet Nine": Have astronomers found a huge new world past Pluto? By Scientific American, adapted by Newsela staff on Word Count 737 This picture is an artist s depiction of what "Planet Nine" might look like. The planet is thought to be gaseous, similar to Uranus and Neptune, and in our solar system out beyond Pluto. Photo: Caltech/R. Hurt (IPAC) In the last 20 years, astronomers have identified about 2,000 new worlds using a telescope in space. These planets orbit stars that lie tens or even hundreds of light-years from Earth. These discoveries are important, but no single planet is likely to be much of a big deal. The new planet is a very different story. It does not circle a distant star. Instead, it is part of our own solar system, a place you would think we had explored pretty well by now. Evidently not. In a new study, California Institute of Technology planetary scientists Konstantin Batygin and Mike Brown say they found strong evidence of a very large undiscovered planet. They say the new planet is orbiting in the solar system s outer darkness beyond Pluto. Space Orbit Oddities This new planet could perhaps be 10 times as massive as Earth. The scientists think it is out there because they have detected oddities in the orbits of space objects nearby. The scientists say they could only be caused by the gravity of a massive planet. The study will be published in The Astronomical Journal, a magazine for scientists.

2 I haven t been this excited about something in quite a while, says Greg Laughlin. He is a planetary scientist at the University of California, Santa Cruz. For the time being, the researchers have named it Planet Nine. The new planet never comes closer than 30.5 billion or so kilometers (19 billion miles) from the sun. Despite its enormous size, if it exists, it would be so dim that it is not surprising that it has not been spotted it yet. Sadly, Brown says, the scientists haven't actually detected it yet. Still, the evidence is strong enough that other experts are taking it seriously. I think it s pretty convincing, says Chad Trujillo of the Gemini Observatory in Hawaii. Batygin and Brown are not the first to argue for an extra planet in our solar system. In 2014, Trujillo and Scott Sheppard, of the Carnegie Institution for Science, argued that there might be something planet-sized out there. The theory was based on the orbits of a handful of space objects. They seemed to be affected by the gravity of an unseen world. A "Crazy" Notion... The first thing Batygin and Brown did, Batygin says, was to look at their data with fresh eyes. "This was a case where we had our noses buried in the data," Brown says, "never stepping back and looking at the solar system from above." The direction of the orbits was an even stronger hint that something was physically moving these distant objects. At first, Brown says, we said there can t be a planet out there that s crazy. However, the only explanation that fit the data was the crazy notion of a planet. The planet that best fits the data would be 10 times as massive as Earth. It would put the new planet in the so-called Super Earth category. It includes many planets around other stars but none, until now, in our own solar system. The new planet would be smaller than Neptune, which is about 17 times larger than Earth. The new planet comes within 19 billion miles (35 billion kilometers) of the sun at its closest. At its most distant, it would be between three and six times as far away. Even at that enormous distance, Planet Nine might be seen with a telescope. Until then, astronomers cannot say definitely that Planet Nine is actually out there. I tend to be very suspicious of claims of an extra planet in the solar system, says Hal Levison. He is a scientist with the Southwest Research Institute in Boulder, Colorado. The question needs to be further explored, he adds.

3 ... And Perhaps A Thrill Overall, however, planetary scientists are clearly thrilled that we might be close to such a major discovery. When I was growing up, Sheppard says, we thought the big planets had all been found. It would be very exciting and very surprising to learn that we were wrong. The mood of the astronomers is captured, Laughlin says, by something British astronomer John Herschel said in It looked like the gravity of an unknown, massive planet was tugging on the planet Uranus. We see it as Columbus saw America from the shores of Spain," Herschel said. Just two weeks later, the planet Neptune was discovered, right where the astronomers said it should be.

4 Quiz 1 According to the article, why would the planetary scientists consider the discovery of a new planet a "big deal"? The new planet is more massive than Earth. "Planet Nine" would be part of our solar system. Viewing the new planet would be exciting. We need another planet to make our solar system complete. 2 According to the article, with which of the following statements would the British astronomer John Herschel AGREE? Scientists should be suspicious of big discoveries. Scientists must always prove their theories. Scientists need to be wrong at times. Scientists need to keep their eyes open for new evidence. 3 Read the paragraph from the section "A 'Crazy' Notion." The direction of the orbits was an even stronger hint that something was physically moving these distant objects. At first, Brown says, we said there can t be a planet out there that s crazy. However, the only explanation that fit the data was the crazy notion of a planet. What does the phrase "crazy notion" imply in the sentence? The scientists thought that the idea of a new planet was silly. The scientists thought a new planet was unlikely to exist. The scientists thought the idea of a new planet was clever. The scientists thought that the new planet was real.

5 4 Read the paragraph from the section "... And Perhaps A Thrill." The mood of the astronomers is captured, Laughlin says, by something British astronomer John Herschel said in It looked like the gravity of an unknown, massive planet was tugging on the planet Uranus. What is the meaning of the word "captured" as used in this paragraph? rescued demonstrated changed forced