WASHINGTON – The year 2008 is turning out to be stellar for astronomy. New discoveries in the sky are popping up like fireflies.

Recent highlights include a whopping haul of new planets around faraway stars. A baby planet caught in the process of forming. An alien solar system that bears a remarkable resemblance to our own. Two stars merging. The littlest black hole ever detected. Organic molecules – the possible stuff of life – discovered on a moon of Saturn and on an alien planet.

On Tuesday, astronomers reported the discovery of 10 extrasolar planets trillions of miles from Earth.

That boosts the roster of alien planets to 287 since the first two were identified in 1996. Using robotically controlled telescopes in Spain, South Africa, Australia, Arizona and Hawaii, an international collaboration known as SuperWASP – for Wide Area Search for Planets – measured slight dips in the brightness of certain stars.

The dips were caused by planets that passed in front of the stars, blocking some of their light.

The new planets range from half the mass of Jupiter, the largest body in our solar system, to more than eight times bigger than Jupiter. One planet zooms around its star – its “year” – in a little more than a day. None is Earth-size or likely to support life.

Also on Tuesday, American and British astronomers using radio telescopes found what appears to be a “protoplanet” orbiting a young star in the constellation Taurus.

The object is a bright clump of material in a dusty disk surrounding the star. If it proves to be an embryonic planet, it would be the youngest such object yet detected.

“We see a distinct orbiting ball of gas and dust, which is exactly how a very young protoplanet should look,” said Jane Greaves, an astronomer at the University of St. Andrews in Fife, Scotland. “In the future we would expect this to condense into a gas giant planet like a massive version of Jupiter.”

Another surprise reported last week was an unusual pair of stars in the Big Dipper that are so close together that they share some of their contents. In combination, they look like a big yellow peanut.

“When two stars orbit each other very closely, they share material, and the evolution of one affects the other,” Jose Prieto, an astronomer at Ohio State University, reported in the Astrophysical Journal.

Also last week, NASA scientists reported the smallest known black hole, an object so heavy that nothing, not even light, can escape from it. This little monster is 15 miles wide but weighs almost four times as much as the sun.

“This black hole is really pushing the limits,” said astrophysicist Nikolai Shaposhnikov at the Goddard Space Flight Center in Greenbelt, Md. “For many years, astronomers have wanted to know the smallest possible size of a black hole, and this little guy is a big step toward answering that question.”