“The international study is led by the joint Japan-New Zealand-American Microlensing Observations in Astrophysics (MOA) and the Probing Lensing Anomalies NETwork (PLANET) programs, using telescopes in New Zealand and Tasmania. Their technique, called gravitational microlensing, takes advantage of chance alignments between stars. When a foreground star passes between us and a more distant star, the closer star can act like a magnifying glass to focus and brighten the light of the more distant one. These brightening events usually last about a month.
“If the foreground star -- or what astronomers refer to as the lens -- has a planet circling around it, the planet will act as a second lens to brighten or dim the light even more. By carefully scrutinizing these brightening events, astronomers can figure out the mass of the foreground star relative to its planet.
“In some cases, however, the foreground object could be a free-floating planet, not a star. Researchers might then be able to measure the mass of the planet relative to its orbiting companion: a moon. While astronomers are actively looking for exomoons -- for example, using data from NASA's Kepler mission - so far, they have not found any.
“In the new study, the nature of the foreground, lensing object is not clear. The ratio of the larger body to its smaller companion is 2,000 to 1. That means the pair could be either a small, faint star circled by a planet about 18 times the mass of Earth -- or a planet more massive than Jupiter coupled with a moon weighing less than Earth.”
Researchers have found evidence of almost 2,000 exoplanets, planets in other star systems. Data from the Kepler space telescope is still being analyzed for evidence of even more planets.
In the meantime NASA is preparing for the deployment of a multibillion dollar James Webb Space Telescope, an infrared optimized device due to be launched in 2018. While the JWST is a multifaceted observatory, similar to the Hubble, it will have a unique technology that will allow it to detect exoplanets and perhaps exomoons as never before.
The James Webb has a device called a “star shade” which would be used to block the light of a target star. It is hoped that absent the glare of a star, the JWST will be able to directly image exoplanets for the first time. It will only be able to hunt for planets orbiting nearer stars, within ten or twenty parsecs, but it will have the potential of being able to directly detect the first Earth-like planet. It would be a world orbiting in the habitable zone of another star and which is detected to have oceans and an atmosphere. The telescope will be able to determine changes in seasons of these worlds, which would be a remarkable accomplishment indeed.