Star HR 8799 was born about the same time as humanity's ancestors — 60 million years ago, after the dinosaurs went extinct and the age of animals that would lead to our evolution was just beginning here on Earth. It's 129 light years away from us, tucked toward the front legs of the constellation Pegasus. It's so close and so brilliant (five times brighter than our own sun) that on a clear night it can easily be spotted by the naked eye.
In 2008, scientists discovered three planetary companions circling within a dusty disk that surrounds the star, just as the nine planets of our solar system are encircled by the Kuiper belt. And they took a picture. It tied for the first direct image ever taken of planets outside our celestial neighborhood. (Another image of the planet Fomalhaut b was released the same day.)
Further observation uncovered another planet. And now, we can watch all four in motion.
This three-second animation is the result of seven years of work by Jason Wang, an astronomy graduate student at the University of California, who compiled dozens of images taken by the W.M. Keck observatory in Hawaii to create the digital equivalent of a flip book.
The black circle at the middle is a result of the device used to block the light from the star so that scientists could detect the much fainter gleam of its nearby planets.
The four glowing globes that orbit it are HR 8799's planets. This animation does not show their full orbits — the planets are so far from their star that it would take more than four centuries to create that video.
But this is a snapshot of four alien worlds orbiting a distant sun. And that's pretty incredible.