The quest for life outside Planet Earth just got a lot more interesting.

NASA on Wednesday revealed it has discovered a "treasure trove" of Earth-sized planets. Dubbed TRAPPIST-1, the system consists of seven Earth-sized planets orbiting around a single, nearby star. Three of these planets are located in what NASA calls the "habitable zone," meaning the area around the parent star where a rocky planet is most likely to have water.

While NASA has identified Earth-like planets before, this discovery sets a new record for the largest number of habitable-zone planets found around a single star outside our solar system. The space agency said all seven planets in TRAPPIST-1 could have liquid water under the right atmospheric conditions, but the three in the habitable zone are most promising.

"This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life," Thomas Zurbuchen, associate administrator of NASA's Science Mission Directorate in Washington, said in a statement. "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 system of planets is 40 light-years away from Earth, or about 325 trillion miles, which is "relatively close" in the grand scheme of things, NASA said. Since they're located outside our solar system, they're technically exoplanets.

Using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST), researchers in Chile previously discovered and announced three planets in the system. NASA's Spitzer Space Telescope confirmed the existence of two of these planets and discovered five additional ones.

NASA said all the TRAPPIST-1 planets are likely rocky, but further observations are needed to determine whether they have any liquid water on their surfaces. The system's star is much smaller than Earth's sun, meaning liquid water could possibly survive on planets orbiting very close to it. All seven of the TRAPPIST-1 planets are closer to their star than Mercury is to our sun.

"The planets also are very close to each other," NASA said. "If a person was standing on one of the planet's 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, the agency added, meaning the same side of the planet is always facing the star. That side would be perpetually day, while the side facing away from the star would be night all the time. "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," NASA said.