NASA’s Exoplanet Discovery – Trappist-1

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Seven earth-sized planets have been discovered recently by NASA, in the constellation of Aquarius. The exoplanet (a planet that orbits a star other than our Sun) system is called TRAPPIST-1, which stands for The Transiting Planets and Planetesimals Small Telescope. The tiny, dim star the planets are orbiting is only about 40 light-years (235 trillion miles) away from the Earth. This is regarded as a huge discovery as this is the first star system known that consists of such a large number of Earth-sized and probably rocky planets.

How were the planets identified?

NASA’s Trappist robotic telescope and exoplanet-hunting Spitzer Space Telescope were used to observe the passage of planets. The telescope operates at infrared wavelengths which glow the brightest from TRAPPIST-1. In passing, celestial bodies block out a small amount of light from the host star, creating shadows. Tiny dimming can therefore be detected. The masses, sizes and densities of the planets can also be estimated. This process is called transit photometry.

There are 7 exoplanets orbiting the dwarf star: this plot shows the decrease in relative brightness from the star when they each cross in front of it. Larger planets cause a deeper

There are 7 exoplanets orbiting the dwarf star: this plot shows the decrease in relative brightness from the star when they each cross in front of it. Larger planets cause a deeper “dip” (as they are blocking more of it) whilst planets further away from the star cause longer “dips”, as they are orbiting more slowly.

This plot shows the decrease in relative brightness during a very unusual event: a triple transit. This occurred on 11 December 2015 and you can see each of the three

This plot shows the decrease in relative brightness during a very unusual event: a triple transit. This occurred on 11 December 2015 and you can see each of the three “dips” as a new planet crosses in front of the star. These data were obtained from ESO’s Very Large Telescope. Two of the planets seen crossing during this event were in the habitable zone.

Are the planets habitable?

Due to the dimness of the parent star, the planets are darker than the Earth. However they are relatively close to it and so all the planets have surface temperatures in the range of 0-100 degrees Celsius.

Of the planets, three of them are located in the habitable zone. It is also discovered that all of them could have liquid water under the suitable atmospheric conditions, which is a key for any life form on Earth to exist.

However, further study and investigations are needed to ensure that the temperatures, surface pressures and chemical fingerprints of water, oxygen and ozone (amongst other molecules) are suitable to support life.

This discovery has contributed a lot in the search of potential habitable environments outside the Solar system. Thanks to the continuous improvement in technology, we might may be able to move home to another world in the near future.

References:

  1. Chou, F., S. Potter, and E. Landau. “NASA Telescope Reveals Largest Batch of Earth-Size, Habitable-Zone Planets Around Single Star .” www.nasa.gov. February 22, 2017. Accessed March 02, 2017. https://www.nasa.gov/press-release/nasa-telescope-reveals-largest-batch-of-earth-size-habitable-zone-planets-around.
  2. Sommerlad, J. “Exoplanet discovery: Five facts you didn’t know about Nasa’s new solar system .” www.independent.co.uk. February 23, 2017. Accessed March 2, 2017. http://www.independent.co.uk/news/science/exoplanet-discovery-nasa-announcement-google-doodle-alien-life-supporting-solar-system-earth-like-a7594801.html.

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