Between 1997 and 2001, the Two Micron All-Sky Survey, with two telescopes located in Chile and Arizona, cataloged almost 500 million astronomical objects1. One of these 500 million was a star, charmingly named 2MASS J23062928-0502285. For anyone looking for a unique baby name, I have a recommendation. In May 2016, a team of astronomers out of the University of Liege in Belgium reported that, using the Transiting Planets and Planetesimal Small Telescope, they had discovered three Earth-sized planets orbiting 2MASS J23062928-0502285.2 Following this discovery, the star was renamed TRAPPIST-1, as it was at the center of the first exoplanets observed with the TRAPPIST telescope. Of note, the acronym comes from the beer made by the Trappist monks in Belgium. A dirty truth about science is that about 25% of your time is spent coming up with names for your projects that are cool acronyms, and naming something after a beer is pretty much the coolest, so I have zero doubt that someone worked really hard to come up with the name.
TRAPPIST-1 is located about 40 light years (235 trillion miles) from Earth, in the constellation Aquarius. For reference, that's only about 10 times further than the Alpha Centuri system, the closest stars to our sun, and really not all that far on an astronomical scale.3 At roughly 8% the mass of our sun, it's about the same size as Jupiter. It's considered an "ultra cool" star, about half as hot as our sun, and is only about 500,000 million years old.4
This week, the same team published a paper in Nature highlighting the observation of four more planets in the TRAPPIST-1 system, as well as releasing a lot more detail on the previously known planets.5 Five of the planets in the system (b, c, e, f, and g) are roughly Earth sized, while the other two are slightly smaller. The system is significantly denser than our solar system, with all seven planets' orbits falling within what would be the equivalent of our sun and Mercury. Given the ultra cool nature of TRAPPIST-1, though, the close proximity doesn't preclude the possibility of liquid water or of habitable temperatures. In fact, three of the planets are located within the habitable zone. This isn't necessarily that impressive though, since estimates of the number of habitable objects within the Milky Way alone range from 500 million to 180 billion.6, 7 A designation of being in the habitable zone only relates to the potential of possessing liquid water, and says nothing about any other features of the object, including atmosphere composition.8 Estimates of the density of the TRAPPIST-1 planets b-g suggest that they are likely rocky, as opposed to gassy, planets.9 Less is known about the seventh planet, but it may be icy.10 That's all the super cool descriptions of the system, but if you want to see some amazing artists' renderings, check out the NASA website.
The scientists on the team studying TRAPPIST-1 believe that "It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds."11 But what does that mean in non-astronomer terms? First of all, there's still a ton of work to do in determining just how habitable these worlds are. We don't know anything about weather patterns or temperatures. We don't know anything about the composition of the atmosphere. We don't know anything about surface pressure. The star is currently being observed by the Kepler telescope, which will be directed that way until March, collecting 70 days worth of data.12 New projects in the next few years will attempt to gather more information about these planets, including the James Webb Space Telescope, which will be launched next year, as well as the Hubble Telescope.13 The TRAPPIST project was also the prototype for a much larger astronomical survey called The Search for Planets Eclipsing Ultra-Cool Stars, or SPECULOOS.14 Refer to what I said earlier about acronyms.
The TRAPPIST survey is basically a really amazing, very early step that will, more than likely, end up to be kind of disappointing in terms of implications. As a non-astronomer scientist, however, I find something really exciting about the discovery (besides that fact that it's still really, really cool). Space discoveries have always been sexy, and that means that they drive scientific innovation. They excite people and inspire people. Some of the United States's best scientific years were driven by the space race. Kids were interested in science and math, and wanted to follow those paths. Government funding of science was growing. The sparkle and hope of discovering Earth-like planets that are potentially habitable could do a lot for public perception of science at a time it is desperately needed. Excited people are more likely to push for more government funding of NASA. Excited kids are more likely to get bitten by the space bug, and those are things that are hugely valuable to our society.
But let's get creative for a few minutes and imagine a future where TRAPPIST-1 turns out to be all we want it to be.15 Everything indicates that views on TRAPPIST planets would be kind of incredible. Remember how close the planets are to each other; you could reasonably look up and see all six others in the sky, and not as the tiny dots of light like we see planets on Earth, but more similarly to the way we see our moon. If the planets have day and night patterns like we do, and not just one side perpetually in light and one perpetually in dark, the day would seem more like our sunset, due to the fact that TRAPPIST-1 is significantly less hot, and therefore less bright, than our sun. Getting there would be the major complication. We currently don't have the technology, and with some sort of object moving at the speed of the Voyager 1 probe, it would take several hundred thousand years, so maybe we should work on extending human longevity first. There are talks of a new type of micro-probe that could be slingshotted using planetary orbits to exoplanets, but even that would take 200 years, so we've got a long wait coming.16
The TRAPPIST-1 system is an incredible discovery, and be on the lookout for more research on it coming out in the very near future. The data from the Kepler observation will be publicly available within a month of the end of the observation, which is a model for how all science should work. We'll be bringing in more information about the possibility of life in the system in the next several years, which is likely going to be cause for great excitement (and the promise of life sustaining conditions in a large number of other systems), or great disappointment (and life sustaining conditions seeming to be more rare than estimated). Either way, there won't be a confirmation of any sort of life in our lifetimes, so instead we're left with something possibly just as good: a renewed sense of wonder.