Alexa Grittani - 3B Mechanical
Posted on: March 12, 2017

NASA’s Spitzer Space Telescope has revealed the largest batch of Earth-size, habitable-zone exoplanets around a single star. An exoplanet is just a term to describe a planet that orbits a star other than the Sun. Seven planets were found orbiting in the TRAPPIST-1 system, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile.

Three of them are located in the habitable zone. Now it is important to understand what “habitable zone” means. Being located in the habitable zone is not the same as being habitable, or fit for human life. The habitable zone refers to a band of potential habitability surrounding a star. So, if planets are found there, they are at the right distance and temperature for liquid water to possibly exist on the surface. To further point out how little the habitable zone tells us about the planets, in our own solar system Earth, Venus and Mars are in or near the habitable zone, but they are so different.

The habitable zone in the TRAPPIST-1 system is much closer to the star because its star is classified as an ultra-cool dwarf (I’m picturing a dwarf wearing sunglasses looking ultra-cool, surrounded by seven Snow Whites). Since it is an ultra-cool dwarf star, all seven planets orbit closer than Mercury does around our sun. Also, all of the planets are much closer together, meaning that to someone standing on one planet, the other planets in the sky could appear larger than the moon does in our own sky.

Still the seven exoplanets are an important discovery because they are, “the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds” explained Michael Gillon, the principal investigator of the TRAPPIST exoplanet survey at the University of Liège, Belgium.

The properties of the planets’ surfaces and atmospheres are yet unknown. While there is still a possibility that all seven planets have liquid water, even if they did, it is only under the right atmospheric conditions that they would be habitable. Based on calculations performed using Spitzer data the densities of the planets are likely to be rocky. This is important because Earth is rocky and is, therefore, the type of planet that we have the most knowledge about.

The TRAPPIST-1 system is about 40 light-years (235 trillion miles) from Earth. This is relatively close, but it would take NASA’s space shuttle 1.5 million years to get there. Still, they are close enough that scientists are able to study them, and will be better able to study them when the James Webb Space Telescope launches in October 2018. The new telescope is a collaboration between NASA, the European Space Agency, and the Canadian Space Agency, and will be an infrared telescope with a 6.5 meter primary mirror.

The TRAPPIST-1 system is a great way for the James Webb Telescope to start its career off. “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.” Do not fret. The scientists are looking for aliens.

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