Scientists say they found an Earth-like planet

Transcription

1 Scientists say they found an Earth-like planet By Scientific American, adapted by Newsela staff on Word Count 971 The two bright stars are (left) Alpha Centauri and (right) Beta Centauri. The faint red star in the center of the red circle is Proxima Centauri. Photo: Wikimedia Commons For years scientists and the public alike dreamed of a day when we would find another planet where humans could live. The safe bet was to guess that the discovery of such a planet would come only after hundreds of years. The safe bet was wrong. Astronomers just made a historic announcement. They believe they have discovered a potentially livable planet beyond our solar system. Astronomers Hope Proxima b Could Be A Livable Planet "Proxima b," as scientists are calling this planet, is still waiting for verification to be considered a planet. But many astronomers are hopeful that our species has uncovered a livable planet right next door. Scientists don't know whether there is water on the surface or if the planet has an atmosphere. They do think both are likely. This would mean the planet could support life.

2 Proxima b is too faint to be seen without a telescope. It is a little more than four light-years away from our solar system. This is more than 260,000 times the distance between the sun and the Earth. The planet is thought to be orbiting Proxima Centauri, which is the closest star to our sun. It is known as a red dwarf star because of its smaller size and dimmer light. Proxima b resembles the Earth in terms of mass and exposure to starlight. It has an day orbit, compared to the Earth's 365 days. Proxima b is likely to be little more than onethird heavier than Earth. It also may have a solid surface with seas and oceans, like Earth. Succeeding in the search for the nearest terrestrial planet beyond the solar system has been an experience of a lifetime, says the study s lead author, Guillem Anglada-Escudé, an astronomer at Queen Mary University of London. We hope these findings inspire future generations to look beyond the stars." Hints Of Proxima b First Seen In 2013 The study's co-author, Mikko Tuomi, an astronomer at the University of Hertfordshire in England, was the first to see hints of Proxima b in He was planet hunting with Anglada-Escudé. Their efforts were combined with other research dating back to the year The scientists were looking for a back-and-forth wobble of the star Proxima Centauri. This could be caused by the gravitational pull of a planet in orbit. Tuomi thought he saw evidence of a wobble. People seem to think we just found the planet. But no, we have believed it was there for years, Anglada-Escudé says. We just had to build an argument to convince others it exists. The "Pale Red Dot" Observing Campaign Tuomi, Anglada-Escudé and others submitted a paper of their observations. At first, others found their evidence unconvincing. Anglada-Escudé responded by spending the next two years developing the Pale Red Dot observing campaign. The researchers wanted to observe the star for a long period of time, so for the first half of this year, telescopes around the world were pointed at Proxima Centauri. Anglada-Escudé and the rest of the Pale Red Dot team used high-tech equipment to observe Proxima for 60 nights in a row last spring. After just 10 days, the Pale Red Dot team knew they had found a planet. "Goldilocks" Worlds Perhaps the most surprising thing about Proxima b is that its existence is not really surprising at all.

3 In recent years, astronomers have all landed on a similar statistical estimate for the number of potentially life-friendly worlds in our galaxy. Somewhere between 15 and 30 percent of the Milky Way s stars should harbor Goldilocks worlds. This is how scientists describe planets that are not too big to be smothered by thick atmospheres and not too small to lose their precious air to space. They must also be in a not-too-hot, not-too-cold orbit where liquid water could exist on their rocky surfaces. As the Solar System formed, the sun sent out energy and particles in a stream called the stellar winds. These powerful winds blew the gases off the four planets closest to the sun. Without their gases, these planets became smaller. Only their rocks and metals were left. That s why they are called rocky, or terrestrial, planets. The four outer planets are much farther from the sun. From such a distance, the winds could not blow away their ice and gases. These outer planets stayed in a gas form. Most of these Goldilocks worlds exist around red dwarf stars, like Proxima Centauri. But could something live on them? Not even experts know this answer. Anglada-Escudé says Proxima b could be verified as a planet within weeks. As news of Proxima b moves through the scientific community, even more astronomers are excited to observe and study it. Researchers want to directly measure Proxima b s size, figure out its mass or its weight as well as calculate its density and estimated composition. In addition, more extensive studies of Proxima Centauri s wobbles would help determine the possibilities for life there. Extremely Large Telescopes Could Be Used To Study Proxima b Proxima b offers a unique opportunity for a new generation of extremely large groundbased telescopes presently under construction around the world. Set to debut in the 2020s and armed with light-gathering mirrors stretching almost 100 feet or more across, such telescopes could conceivably obtain actual pictures of Proxima b. This would unveil otherwise unavailable information about its composition and history. The biggest of these next-generation behemoths will be the European Extremely Large Telescope (E-ELT) of the European Southern Observatory (ESO), which could begin operations in Chile as early as What's more, Proxima b's discovery is fueling new interest in searches for radio- or laserbased messages beamed toward Earth from any technologically talkative aliens on the planet, as well as futuristic proposals to send robots there to explore. "The search for life on Proxima b comes next," says Anglada-Escudé.

4 Quiz 1 Which of these details from the article MOST helps shape the main idea? Humans have wondered for years whether there are other planets to live on. Astronomers have evidence suggesting Proxima b is a livable planet. Proxima b is too small to be seen without a telescope. The existence of Proxima b is not that surprising to many scientists. 2 The central idea of the article is developed by: examining the advances scientists have made in studying Proxima b describing evidence proving that Proxima b is a planet and not a star highlighting the fact that Proxima b has been studied for many years already comparing Proxima b to other known planets within the Milky Way galaxy 3 Which of the following answer choices BEST represents Anglada-Escudé's reaction to the Pale Red Dot team's findings? sadly defeated nervously quiet cautiously hopeful confidently pleased 4 What caused Mikko Tuomi to believe Proxima b was a planet? He read the research of Anglada-Escude. He saw the star Proxima Centauri move in a particular way. He realized that there was a "pale red dot" near Proxima b. He discovered that Proxima b likely contained water.

5 Answer Key 1 Which of these details from the article MOST helps shape the main idea? Humans have wondered for years whether there are other planets to live on. Astronomers have evidence suggesting Proxima b is a livable planet. Proxima b is too small to be seen without a telescope. The existence of Proxima b is not that surprising to many scientists. 2 The central idea of the article is developed by: examining the advances scientists have made in studying Proxima b describing evidence proving that Proxima b is a planet and not a star highlighting the fact that Proxima b has been studied for many years already comparing Proxima b to other known planets within the Milky Way galaxy 3 Which of the following answer choices BEST represents Anglada-Escudé's reaction to the Pale Red Dot team's findings? sadly defeated nervously quiet cautiously hopeful confidently pleased 4 What caused Mikko Tuomi to believe Proxima b was a planet? He read the research of Anglada-Escude. He saw the star Proxima Centauri move in a particular way. He realized that there was a "pale red dot" near Proxima b. He discovered that Proxima b likely contained water.