Discovery of TRAPPIST-1’s seven Earth-sized planets is incredibly good news.

From the scientific point of view how big news is the discovery of seven Earth-sized planets and what does this discovery tell us about the possibility of an alien life? Read few comments.

A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. Credit: https://www.nasa.gov/ - R. Hurt/T. Pyle

A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. Credit: https://www.nasa.gov/ – R. Hurt/T. Pyle

James Kasting, Distinguished Professor of Geosciences, Penn State University

Whether one views this discovery as big or small depends on one’s perspective. From the standpoint of knowing whether life exists off the Earth, it’s a small step. There is no guarantee that any of these newly discovered planets are inhabited, or even habitable. But, from the standpoint of advancing our search for extraterrestrial life, it’s a big deal! This discovery will interest more astronomers in looking for Earth-like planets, and it will interest more of the general public in the search for life on planets around other stars. People elect Congressmen, and Congress determines NASA’s budget for doing such things as building space telescopes. So, hopefully, this will help NASA get the money to actually answer the question.

Mike GruntmanProfessor of Astronautics, University of Southern California

We do know about existence of planets around other stars. What is particularly important in the latest discovery is that these planets are relatively close, on galactic scales, to us. Consequently, our continuously improving observational techniques would allow studying in depth those planets. Because of their proximity, the planets present a unique opportunity to learn more about them and advance understanding of their properties not achievable  for most other discovered exoplanets.

Joshua Winn, Professor of Astrophysical Sciences, Princeton University

The announcement of all the new planets around TRAPPIST-1 is incredibly good news. This system has something for everyone. This nearby small star has not just one, but seven terrestrial-sized planets, in the size range between Mars and Earth. We know they exist because when they circle around the star, they cause miniature eclipses, blocking a little bit of the starlight from reaching our telescopes. And because the star itself is to tiny (only 10% the size of the Sun), those eclipse signals are big and relatively easy to study.

For this reason planetary scientists will be able to study the atmospheres of these planets with the upcoming James Webb Space Telescope, to be launched in 2018. They’ll search for molecules that might betray the presence of life, or at least give clues about the geological and atmospheric processes on those planets. Nobody knew we’d have this opportunity so quickly! I had been worried it would take 5-10 more years to find such a favorable system.

Physicists are delighted that the planets are in an intriguing arrangement around the star, much closer together than the planets in the solar system. The planets’ orbital periods — the time needed to go all the way around the star — seem to have special mathematical relationships. The ratios are simple fractions, in just the same way that consonant musical notes have audio frequencies with simple ratios. A perfect fifth has notes with frequencies in the ratio 3:2, and so do some the planets’ orbital periods! It will be fun to try to figure out what causes this planetary harmony. It may be that the planets used to be more widely spread apart, but gravitational interactions early in the system’s history brought them together nearly as close as they could possibly be.

Engineers who are dreaming up new ways to propel spacecraft to the stars will be glad that TRAPPIST-1 is relatively nearby: “only” 40 light-years from our solar system. There are a few known planets that are even closer, but TRAPPIST-1 is the most attractive destination because there will be seven potentially Earth-like worlds to explore.

And of course artists and science fiction writers now have 7 new nearby worlds to stimulate their imaginations!

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