The Hubble Space Telescope has successfully identified and characterized the host star of one of the most distant planetary systems yet discovered, reports astronomer David Bennett of the University of Notre Dame University. The method used is called "microlensing," which observes distant objects indirectly by keeping track of "light-bending."

What happens is that light waves from a visible star are gravitationally bent when a smaller, invisible object with mass passes in front of it. This causes the visible object - known as the "lensing" star - to brighten and dim over a period of time. The "spike" in brightness indicates that a smaller object - a planet, or in this case, an entire solar system - too small to be observed directly is passing in front of the lensing star.

Unfortunately, if the passing object is an entire solar system, this kind of observation tells astronomers little about the host star beyond the fact that it exists. Bennett's team was able to determine the specific characteristics of this particular star (dubbed "OGLE-2003-BLG-235L/MOA-2003-BLG-53L") because it's color was different than that of the lensing star behind it.

The researchers concluded that the host star - some 19,000 light years distant - has little over 3/4 of the Sun's mass. Although smaller in terms of mass, it appears to have greater density. The planet is similar to Jupiter in terms of make-up (a gas giant) and orbit, although it is over two and a half times as big.