Scientists recently announced the discovery of seven Earth-like planets in a solar system close to our own. The “sun” of this system is a small, cool star called TRAPPIST-1A. So why all the excitement? Earth-like planets capable of supporting life are rare. Finding one among all the non-habitable planets in our galaxy is a little like winning the lottery, but finding several all at once is truly extraordinary! Here are ten things to know about this exciting new discovery:

  1. TRAPPIST is an acronym that stands for Transiting Planets and Planetesimals Small Telescope, the instrument which was use to detect the first planets in this system. Later, scientist used larger earth and space-based telescopes to confirm and expand their findings. TRAPPIST-1 was the first system discovered with this telescope. Scientists designated its central star as TRAPPIST-1A and the orbiting planets as TRAPPIST-1 b-h.
  2. Scientists discovered the planets using a method called transit photometry. As a planet orbits the central star in its solar system, it sometimes blocks the star’s light in what we more commonly recognize as an eclipse. Even if the planet is too small to be seen from Earth, scientist can see and measure that temporary dip in the star’s brightness. By measuring the magnitude and frequency of those dips, we can tell how many planets, their approximate size, and their orbital period. So far seven planets have been discovered orbiting TRAPPIST-1A, but there could be more.
  3. The TRAPPIST-1 star is much smaller and cooler than our own sun. Known as an ultracool M-Dwarf star, it burns at a temperature of about 4,100°F, which is less than half that of our sun, and is much less bright. This slow, cool burn means that the star could live for 5 trillion years or more, compared to the meager 10 billion year life span of our own sun.
  4. Because the central star is so cool, the planets in the TRAPPIST-1 system were able to form and orbit much more closely. The entire system could sit inside the center of our own solar system, with all seven planets neatly fitting inside Mercury’s orbital path.
  5. Of the seven planets discovered in TRAPPIST-1’s system, at least three or four are thought to lie in the habitable zone, far enough from the heat of the star to prevent oceans from evaporating, but still close enough to keep the water from freezing. TRAPPIST-1 b and c, the closest planets to the star, could be hot and dry, while TRAPPIST-1 h, the farthest star, could be completely ice-bound. Those in between (TRAPPIST-1 d-g) are more likely to be just right.
  6. Many, if not all, of the TRAPPIST-1 planets are believed to be tidally locked, meaning that one side of the planet always faces the sun. This leads to one bright, warm side of the planet and one cold dark side. If life were possible on these planets, it would be most likely found along the terminator, the narrow band where the light and dark sides meet.
  7. Standing on one of these new planets, the light of the TRAPPIST-1 star would look much dimmer and redder than our own sun and would alter how colors appear. Green plants, for example, might appear as a deep maroon color or even black.
  8. A year on a TRAPPIST-1 planet could be as short as one day (for TRAPPIST-1 b) or as long as 20 days (for TRAPPIST-1 h).
  9. TRAPPIST-1 is actually a close neighbor of our own solar system. It lies just 39 light years away, or a mere 229 trillion miles. If you were travel in the fastest space craft we have now it would take you nearly 817,000 years to reach TRAPPIST-1, just blink of the eye compared to the approximately 2 billion years it would take you to cross the Milky Way.
  10. Looking up into the night sky from Earth, you won’t be able to see TRAPPIST-1 with your naked eye, but you can find its approximately location by tracing the constellation Aquarius.

You can further explore TRAPPIST-1 and other exoplanet systems using the NASA’s EYES app.

Images by: NASA/JPL/CalTech