Groundbreaking Discovery Of Exoplanets Beyond The Milky Way

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Microlensing image that detected the extragalactic planets (Photo Credit: University of Oklahoma)

With over 3,500 exoplanets confirmed as of January 2018 and more being observed on a regular basis, the discoveries have become almost routine. However, all the planets found thus far have been within the Milky Way, the galaxy that contains our solar system. Now, scientists from the University of Oklahoma believe they may have found evidence of trillions of planets beyond our galaxy.

The research team, led by astrophysicist Xinyu Dai and postdoctoral student Eduardo Guerras, accidentally stumbled upon the exoplanets, which lie 3.8 billion light-years away, accidentally while studying the environment around a black hole using data obtained from NASA’s Chandra X-ray Observatory. Guerro says, “There was not the slightest chance of observing these planets directly, not even with the best telescope one can imagine in a science fiction scenario.” Hence, the only way to confirm their suspicion was with a technique called microlensing. Similar to using a magnifying glass to bend light waves and focus them elsewhere, the process takes advantage of a large object’s gravitational pull to magnify and bend light from a distant object behind it. This allows experts to observe distant planets even if they emit little light.

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The researchers say, unlike Earth, the newly-discovered worlds are not bound in place by their stars. They either float freely through space or loosely revolve around their stars. What is even more intriguing is the evidence of about 2,000 exoplanets around a single star. Based on the fact that the Milky Way has about 250 billion stars, Dai says, "We can estimate that the number of planets in this faraway galaxy is more than a trillion.”

While experts are not refuting the existence of the planets, they believe more research needs to be done to confirm the large number. Przemek Mróz, a researcher at the University of Warsaw in Poland, says, “The exact number of planets in their analysis depends on specific assumptions, and the uncertainties are large. Examining similar variations in other galaxies should help to refine that number.” David Bennett, a gravitational expert at NASA, agrees, saying the researchers need to consider other possible scenarios, such as the presence of brown dwarfs, which can be mistaken for planets.

A visible-light image of a gravitational lens captured by the Hubble Space Telescope (Photo Credit: NASA/ESA/Hubble Space Telescope)

Dai is not upset by the skepticism. The researcher, who published the study in The Astrophysical Journal Letters on February 2, 2018, says, "We hope other teams publish independent analysis to confirm our findings. I think this is a case where scientific discoveries can be triggered by the spark of ideas." As for the possibility of finding aliens? Bennet says while certainly plausible, “Communication with life in another galaxy would be very, very slow.”

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assumptionsastrophysicistblack holeboundemitevidenceexoplanetsgravitationalintriguingmilky wayplausiblepostdoctoralrefutingskepticismtechniquetriggeredvariations

Reading Comprehension (8 questions)

  1. Why has the discovery of exoplanets become almost routine?
  2. What is unique about the ones discovered by University of Oklahoma scientists?

Critical Thinking Challenge

List two factors that are necessary for a planet sustain life...


Vocabulary in Context

“The researchers say, unlike Earth, the newly-discovered worlds are not bound in place by their stars.”

In the above sentence, the word bound most likely refers to:


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  • Oh hi markMonday, November 5, 2018 at 2:04 pm
    This is so cool I LOVE learning about space i really want to work for nasa by the way i know where Nasa is
    • MinetressASFT32Wednesday, October 24, 2018 at 12:36 pm
      I love learning about space! This is cool! Especially new planets and investigations. Think about it. Contact with life in a different galaxy!!! It could be another spiral galaxy and I believe that it will take a long time to find different life’s in another galaxy because some of the planets and stars in our own galaxy we can’t even get that close to! Say if you are excited to find a new species!
      • Hello how are uThursday, October 11, 2018 at 9:54 am
        i wonder if it has aliens or something that we have never discovered
        • HiTuesday, October 9, 2018 at 10:19 am
          Weird but cool at the same time though
          • A51Thursday, October 4, 2018 at 7:06 am
            I wonder if it has alien life forms
            • A51Thursday, October 4, 2018 at 7:05 am
              I wonder if it contains alien life forms.
              • plante 50Wednesday, October 3, 2018 at 8:37 am
                I 'm scratching on the walls
                • plante 50Wednesday, October 3, 2018 at 6:01 am
                  • plante 50Tuesday, October 2, 2018 at 11:46 am
                    I feel as if this is a greats descuvy every
                    • MhmmmMonday, May 28, 2018 at 4:59 pm
                      I feel that there is no point looking for aliens because how much research we would have to do to be able to communicate with them would be expendential us or them would have to learn English mandarin French or any language to communicate with us through this would take years and they may not understand what we’re trying to do

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