Scientists May Have Discovered the First Planets Outside the Milky Way (washingtonpost.com)

Using data from a NASA X-ray laboratory in space, Xinyu Dai, an astrophysicist and professor at the University of Oklahoma, detected a population of planets beyond the Milky Way galaxy (Warning: source may be paywalled; alternative source). The planets range in size from Earth's moon to the massive Jupiter. From the report: There are few methods to determine the existence of distant planets. They are so far away that no telescope can observe them, Dai told The Washington Post. So Dai and postdoctoral researcher Eduardo Guerras relied on a scientific principle to make the discovery: Albert Einstein's theory of relativity. Einstein's theory suggests light bends when tugged by the force of gravity. In this case, the light is coming from a quasar -- the nucleus of a galaxy with a swirling black hole -- that emits powerful radiation in the distance. Between that quasar and the space-based laboratory is the galaxy of newly discovered planets. The gravitational force of the galaxy bends the light heading toward the Milky Way, illuminating the galaxy in an effect called microlensing. In that way, the galaxy acts as a magnifying glass of sorts, bringing a previously unseen celestial body into X-ray view. In a university news release, Guerras had a less formal way to describe the complicated process: "This is very cool science."

Comments

Re:Like detecting a butterfly across the ocean

[DrTJ]

No, this is far, far, far more impressive than that.

These planets are (according to the article) 3.8 billion lightyears away, i.e. 3.5*10^22 km. At that distance, a planet appears to be *extraordinarily* small.
If we take your France - New York example (Paris-New York = 5681 km), an earth-sized planet (included in the size range mentioned in the article) would - from Paris - have an apparent size of 2*10-15 m.

I.e. the same size as an alpha particle (Helium nucleus).

"This is very cool science" - Indeed!

Misleading story

[JoeRobe]

The picture that goes with the story is pretty, but carries no actual information about the planets that were detected. The story also gives the impression that the planets were actually imaged thanks to microlensing, which I donâ(TM)t think is true. Does anyone have access to the original AJL article?

My understanding (from the OU press release and abstract) is that they analyzed the high frequency fluctuations of atomic line energy shifts of the lensed light to determine that there were small, fast moving objects in the galaxy. They modeled those fluctuations to determine planets in the size range of moon to Jupiter were consistent with what they saw.

If thatâ(TM)s correct, then what theyâ(TM)re able to do here is impressive. Theyâ(TM)re claiming to be able to identify the presence of small objects based upon their contribution to the lensing from a much larger parent object.