Remarkable movie shows alien planets orbiting another star

Astronomers have used a specialised camera attached to a powerful telescope to produce the first remarkable “movie” of a family of planets circling another star.

HR 8799 planets
The animated movie produced by Jason Wang from images taken by Christian Marois.

The incredible sequence shows four alien worlds, each larger than Jupiter, orbiting a young star that is five times brighter than the Sun.

Dubbed HR 8799, it lies 129 light-years away in the constellation of Pegasus, the winged horse, and is just visible with the naked-eye in a dark, moonless sky.

The movie was compiled from eight images taken over seven years at the W.M. Keck observatory in Hawaii.

That is too short a period to capture more than a portion of the planets’ orbits because the closest to the star circles it in about 40 years while the most distant takes more than 400 years.

Recent advances in telescope technology allowed astronomer Dr Christian Marois from Canada to capture the individual images, using a tiny mask to hide the glare from the star and reveal the faint glow of the planets.

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They were put to gather to produce the animation by astronomy student Jason Wang, of the University of California, Berkeley, which focuses on the science of planets outside our own Solar System – called exoplanets – in a NASA-sponsored project.

The planets orbiting HR 8799 are some of the first to be discovered by directly imaging the star’s neighbourhood with a sensitive camera. Another success was to picture a planet orbiting Fomalhaut, which is one of the brighter stars in the night sky.

W.M. Keck Observatory
The W.M. Keck Observatory is a pair of telescopes, each using a 10-metre wide main mirror as its eye on the sky, at the summit of Mauna Kea, Hawaii. Image credit: T. Wynne / JPL

Wang used a special computer software to fill in the orbital gaps between the eight separate images of HR 8799 and produce a smooth-flowing movie.

The planets are believed to be gas giants, like Jupiter, and so not a potential home to the sort of life found on rocky worlds like our own. They all lie many times farther away from their host star than the Earth does from the Sun.

Read more about this amazing imaging at the Many Worlds blog. And see the star HR 8799 for yourself (but not its planets) using our chart below.

Position of HR 8799
The position of the star HR 8799 after dusk in late January is indicated by the circle, close to one edge of the Square of Pegasus. It should be easy to spot with binoculars. Chart by Skymania, using Stellarium.
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By Paul Sutherland

Paul Sutherland has been a professional journalist for nearly 40 years. He writes regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy, plus he has authored three books on astronomy and contributed to others.

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