In the last week of February, NASA announced the discovery of a spectacular “sister solar system,” a mere 39 light-years away, boasting not one, but seven Earth-size planets, all of which huddle around their ultra-cool dwarf star TRAPPIST-1, much like a family around a campfire.
They appear to be rocky; have surface temperatures ranging from 32 to 212 Fahrenheit; and even host liquid water.
Nature describes the star system as a “compact analog of the inner solar system.” It’s so compact, in fact, that if you were standing on the surface of one of these planets, the neighboring planets would sometimes appear even larger than our Moon does in our own sky.
The closest planet takes a mere 1.5 days to orbit its parent star; the sixth, 13 days. Compare that to our own solar system, where Mercury takes 88 days to orbit the Sun; Neptune, the most distant planet, 165 years.