NASA’s Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.
The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. All of these seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.
“This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” said Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington. “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”
But before you pack your spaceship with extra gas and set out to meet the new neighbors, you should keep in mind that the new system is about 40 light-years (235 trillion miles) from Earth, in the constellation Aquarius. So, while they may have the technology to come visit us, we are not so ready.
Because they are located outside of our solar system, these planets are scientifically known as exoplanets. This particular exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system. Assisted by several ground-based telescopes, including the European Southern Observatory’s Very Large Telescope, Spitzer confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.
The new results were published Wednesday in the journal Nature, and announced at a news briefing at NASA Headquarters in Washington.
Using Spitzer data, the team precisely measured the sizes of the seven planets and developed first estimates of the masses of six of them, allowing their density to be estimated.
Based on their densities, all of the TRAPPIST-1 planets are likely to be rocky. Further observations will not only help determine whether they are rich in water, but also possibly reveal whether any could have liquid water on their surfaces. The mass of the seventh and farthest exoplanet has not yet been estimated – scientists believe it could be an icy, “snowball-like” world, but further observations are needed.
“The seven wonders of TRAPPIST-1 are the first Earth-size planets that have been found orbiting this kind of star,” said Michael Gillon, lead author of the paper and the principal investigator of the TRAPPIST exoplanet survey at the University of Liege, Belgium. “It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds.”
In contrast to our sun, the TRAPPIST-1 star – classified as an ultra-cool dwarf – is so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system. All seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun. The planets also are very close to each other. If a person was standing on one of the planets’ surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth’s sky.
The planets may also be tidally locked to their star, which means the same side of the planet is always facing the star, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes.
According to Chabad.org (“Is There Life on Other Planets?“), several Torah scholars of past generations have discussed the possibility of life on other planets. Rabbi Chasdai Crescas (Spain, 1340–1411) wrote that there is nothing anywhere in Torah that negates such a possibility. Rabbi Yosef Albo (Spain, 1380–1444) disagreed. Rabbi Pinchas Horowitz (Poland 1765-1861) cites Albo, but rejects his thesis.
Shortly after the first moon landing, the Lubavitcher Rebbe pointed out that there is support in Torah for the notion that life exists on other planets. Furthermore, we can know something about that life through deduction from what the Torah tells us. He relied on the Talmudic tractates of Shvu’ot and Mo’ed Katan, which suggest that, in the Book of Judges 5:23, when Deborah the prophetess says “Cursed be Meroz! Cursed, cursed be its inhabitants, says the angel of God,” she is referring to a star named Meroz (could be a planet, too, since, for instance, Mercury’s Hebrew name, Kokhav, means star).
Next, the Lubavitch website wonders if these inhabitants of foreign planets are intelligent, and answers that since intelligence is defined by the Torah as the capacity to make decisions with free will, and free will is only possible where there is Torah, and the Torah’s account of the story of Creation does not include its being handed down on other planets, its stands to reason that aliens from elsewhere are not intelligent.
Happy star gazing!