Scientists at NASA announced the discovery of seven Earth-like planets orbiting a single star, TRAPPIST-1, on Feb. 22.

Located outside of our solar system, the planets surrounding TRAPPIST-1 are known as exoplanets. The discovery of the star and its planets marks the first time scientists have found and been able to observe a seven-planet system of Earth-sized bodies around a single star.

“At least three of the planets are in the so-called ‘Goldilocks zone,’ which means that they are in the region that could possible be at a temperature that would allow for liquid water to exist on the surfaces,” astronomy and physics teacher Mark Brada said.

Only three of the planets in the TRAPPIST-1 system are situated in the “Goldilocks zone,” also known as the “habitable zone,” the area around a parent star where a rocky planet is most likely to have liquid water.

“While three of the planets of TRAPPIST-1 are in the Goldilocks zone [. . . all the planets] could potentially support life,” Director of the Griffith Observatory Dr. Edwin Krupp said. “Of course, at the moment, we really don’t know what supports life. That’s why we follow the water, because in all of the examinations of the circumstances that permit life to exist, water is the key aspect of that. We look for liquid water because we know it works.”

These exoplanets in the Milky Way Galaxy are approximately 40 light years, or 235 trillion miles, away from Earth.

“[Something] that makes that system pretty cool is that this star is pretty close to our sun, and so that makes it a lot easier to keep observing these planets to try and see what they’re made out of,” Stanford professor of physics Dr. Bruce Macintosh said. “Right now, we don’t know, we just know they are about the radius of the earth; they could be rocky planets with an atmosphere, they could be made out of hydrogen gas. There’s no way we can tell the difference yet, but because the star is so close, we might be able to measure what their really made out of and if they’re earth-like or not.”

The small distance between our solar system and that of TRAPPIST-1 gives scientists hope for the discovery of other nearby solar systems beyond TRAPPIST-1.

“The fact that it’s relatively close by is significant in that it most likely means planetary systems like this, like our own or like the one in TRAPPIST-1, are even more common than we had considered before, and I think that’s the main reason why that’s so interesting,” Brada said.

The distance between these planets and TRAPPIST-1 also lets scientists predict whether the temperatures of these planets are suitable for life.

“Often when we see planets, they are giant ones, like our solar system; there’s giant planets like Neptune and small rocky planets like Venus or Mars. In this solar system, all the planets they found were Earth-sized. The small rocky planets are the ones that could potentially harbor life someday,” Dr. Macintosh said. “[In] this system especially, several of those planets orbit the right distance from the sun, not too much sunlight, not too little sunlight, just the right amount of sunlight, so that it could have Earth-like temperatures.”

According to NASA, the system of planets is named after the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, which discovered three of the planets in May of 2016. With NASA’s Spitzer Space Telescope, the existence of two of the three planets was confirmed, and five additional planets were discovered this year.

An infrared telescope was able to detect TRAPPIST-1 because the parent star of the system glows brightest in infrared light, which is undetectable with the human eye.

Following the discovery of these exoplanets, scientists used data from the Spitzer Space Telescope to calculate these planets’ sizes and masses.

“There are two significant projects underway that will be looking with much greater precision and detail than we’ve been able to do with the instruments so far. The WEBB space telescope, at the moment, is scheduled for launch at the end of 2018,” Dr. Krupp said. “Now, it’s not a case of detecting them, it’s a case of understanding them physically. The TRAPPIST-1 discovery is in fact important because it’s the first time that we’re seeing a whole system of smaller worlds.”

NASA’s Hubble Space Telescope has begun a screening of four of the planets in the TRAPPIST-1 system, including the three in the habitable zone, to search for evidence of atmospheric conditions suitable for supporting life.

“The discovery of seven Earth-like planets orbiting a nearby star is exciting, but not unexpected,” UCLA professor of physics and astronomy Dr. Jean Luc-Margot said. “We have known for a few years now that there are tens of billions of Earth-like planets in the Milky Way Galaxy. The number of habitable planets suggests that life elsewhere may be common.  We have no evidence of other forms of life at this time, but we are searching for it.”