Although nebulous and vast, it is surprising to remember that outer space is actually a common fixture in our everyday lives. During the day there is the sun, and at night the moon and stars to keep us company as our globe spins through space. Maybe it is here where the true depression of an overcast sky lies; a claustrophobic shroud that blocks the comforting gaze of the extraterrestrial bodies that watch over us. Man's fascination with the extraterrestrial is as old as time and the urge to search for friends is insatiable. The usual line of questioning leaves room for hope; How many billions of solar systems exist? Shouldn't the probability be high that there is at least one somewhat similar to our own?

Last month, a team of scientists from around the world made a breakthrough in the search for earth like planets when they successfully used a new technique to spot an orbiting planet in a solar system 20,000 light years away. The new planet, named OGLE-2005-BLG-290 Lb is 5 and a half times larger than the earth, but is still the smallest planet yet discovered outside our own solar system.

At such a distance, there is no way to actually see an object of similar size to the earth, it must be inferred by the new method of gravitational microlensing. To understand this technique--which was first theorized by Einstein some 70 years ago--it might be helpful to review some of the basics of photography. In a camera, a lens bends light rays entering the camera to focus an image onto film. Gravitational microlensing is similar, but in this case a star is the light source, a telescope on earth is the film and the lens is a planet passing in between the star and telescope. The gravitational pull of the planet actually bends the light emerging from the star, causing the perceived brightness of the star to change slightly from our vantage point on earth. Based on this change in brightness, astronomers can determine both how large the planet is and how far away it is from the star it orbits. Factoring in the size of the star, they can also deduce the temperature of the planet and whether it is solid or gaseous.

Roughly 200 planets beyond the reaches of our solar system have been cataloged so far, but almost all are gaseous giants more similar to jupiter, and discovered using a different method. Microlensing is the first method that allows discovery of smaller planets. Researchers know that BLG-290 has a solid core like the earth because its mass is too small to hold it together if it were gas. The new method will help to determine how common small planets are in our galaxy. This might lead to the discovery of a planet with a temperature range similar to earth's. This feat may just be the golden fleece of astronomy, worth far more than all the pot Carl Sagan ever smoked.

In other news from outer space, a new object discovered within our own solar system has re-ignited the hot debate over whether or not our good friend Pluto/Charon is actually deserving of planet status. UB 313, and orbiting body even further away than Pluto clocks in with a diameter of 3000 km, 700 km greater than that of Pluto. So either UB is the 10th planet circling our sun, or neither Pluto nor UB should be wearing the planet ring. It seems like either way My Very Eager Mother Just Served Us Nine Pizzas is going to need a revamp.

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