This is a fascinating solar system. It has seven earth like planets orbiting very close to their star. Since the star is much dimmer than our Sun, these planets have earth like climate.

"if we could arrange to move all seven of these worlds to our own solar system, they would fit within the orbit of Mercury"

Since these planets are so close to each other, they would appear as round balls in the sky.

"For example, on the third rock from this dim sun, the second rock would look bigger than the moon does to us. Compare that our own situation, where Venus is only a bright speck. The TRAPPIST-1 worlds would also move far more quickly across the sky than you’re used to. In a matter of minutes, they would change their positions relative to background stars."

Interplanetary travel would be much easier.

"Our best spacecraft could take you to Mars in six months. To shuttle between neighboring TRAPPIST-1 planets would be a weekend junket."