We May Not Be Alone: New Planets Similar to Earth

The Spitzer Space Telescope detected seven planets similar to the Earth in size, diameter and temperature, NASA announced on a conference on February 22. They orbit TRAPPIST-1 (The Transiting Planets and Planetesimals Small Telescope), an ultracool dwarf star. Three of those planets are located in the habitable zone around the star, which makes it possible for them to contain liquid water. The obvious conclusion: there is a chance that these planets have the conditions necessary to sustain life or that they even do currently have life on them.

This artist’s concept appeared on the February 23rd, 2017 cover of the journal Nature announcing that the TRAPPIST-1 star, an ultra-cool dwarf, has seven Earth-size planets orbiting it. Any of these planets could have liquid water on them. Planets that are farther from the star are more likely to have significant amounts of ice, especially on the side that faces away from the star.
The system has been revealed through observations from NASA’s Spitzer Space Telescope and the ground-based TRAPPIST (Transiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories. The system was named for the TRAPPIST telescope.

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at Caltech/IPAC. Caltech manages JPL for NASA.

Last May, researchers found three exoplanets (a name given to planets outside of our solar system) orbiting TRAPPIST-1. The new discovery not only confirmed, but also expanded the claim: instead of three planets now we have seven of them, very similar to our Earth.

TRAPPISТ-1 with its planets is relatively close to us – about 40 light-years (approximately 235 trillion miles) away. While it may sound counterintuitive, light-years are a measure of distance, not time. Forty light-years is equal to the distance that light travels in 40 years, which is not as bad as it might seem. In comparison, the distance between the Earth and the nearest black hole is around 2,800 light-years.

TRAPPIST-1 is much smaller and cooler than the Sun, and is only slightly larger than the planet Jupiter. This explain why it is possible for the newly discovered planets to be in such close proximity to their star. The relative size of the planets and the star itself can be seen on the official illustration below.

This chart shows, on the top row, artist concepts of the seven planets of TRAPPIST-1 with their orbital periods, distances from their star, radii and masses as compared to those of Earth. On the bottom row, the same numbers are displayed for the bodies of our inner solar system: Mercury, Venus, Earth and Mars. The TRAPPIST-1 planets orbit their star extremely closely, with periods ranging from 1.5 to only about 20 days. This is much shorter than the period of Mercury, which orbits our sun in about 88 days. The artist concepts show what the TRAPPIST-1 planetary system may look like, based on available data about their diameters, masses and distances from the host star. The system has been revealed through observations from NASA’s Spitzer Space Telescope and the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories. The system was named for the TRAPPIST telescope. The seven planets of TRAPPIST-1 are all Earth-sized and terrestrial, according to research published in 2017 in the journal Nature. TRAPPIST-1 is an ultra-cool dwarf star in the constellation Aquarius, and its planets orbit very close to it. NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at Caltech/IPAC. Caltech manages JPL for NASA.

The new system is different from our Solar System, but these differences is what makes it so interesting. Here are some facts about the new exoplanets:

  • Since they are located closer to TRAPPIST-1, they rotate around it much faster than the planets in our system. They make the full circle around the star in just a few Earth days.
  • The planets are so close to each other that if you were lucky enough to stand on one of them, you would see the rocky surface of the other planets in the sky.
  • An exoplanet may or may not rotate around its own axis. If it does not, one of its sides will experience permanent “night”, while the other will experience permanent “day”.

The discovery is exceptionally exciting for science-enthusiasts, but disappointing for the wide public. Internet went crazy after NASA announced it is going to hold a press-conference, and it did not take long for speculations about an upcoming confirmation of the existence of aliens to spread rapidly around the web. As usual, the discovery was a bit more subtle and the presence of alternative forms of life was not confirmed. Yet, their existence still remains a possibility.

As Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington, put it: “This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,’’ he continued, “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.”

The planets currently continue to be scanned by NASA’s most powerful Hubble Space Telescope. The upcoming James Webb Space Telescope, launching in 2018, will also join the effort of exploring the system of TRAPPIST-1.

It may be the first system discovered similar to ours, but there is no doubt it is not the last one. With the advancement of technologies, news about planets and speculations about their implications will become more common. Much is yet to be explored.

Enjoy the little video that NASA put together to help us understand their findings:

 

Maryam Israelyan

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