Our solar system has a tail, just like comets. Now the U.S. space agency can prove it.

Scientists revealed images Wednesday showing the tail emanating from the bullet-shaped region of space under the grip of the sun, including the solar system and beyond. The region is known as the heliosphere, and the tail is called the heliotail.

Japan's nuclear regulator says radioactive water from the crippled Fukushima power plant is probably leaking into the Pacific Ocean, a problem long suspected by experts but denied by the plant's operator.

Officials from the Nuclear Regulation Authority said a leak is "strongly suspected" and urged plant operator Tokyo Electric Power Co. to determine where the water may be leaking from and assess the environmental and other risks, including the impact on the food chain. The watchdog said Wednesday it would form a panel of experts to look into ways to contain the problem.

Astronomers on Wednesday reported their best observation yet of a massive star embryo growing within a dark cloud -- the largest stellar "womb" ever spotted in our Milky Way galaxy.

The star, which could grow to 100 times the mass of our Sun and up to a million times brighter, was spotted by the most powerful radio telescope on Earth -- the ALMA international astronomy facility located in Chile, according to a paper published in the journal Astronomy and Astrophysics.

The latest models of Mercedes cars cannot be sold in France as they still use an air conditioning refrigerant the EU says emits excessive greenhouse gases and should be replaced, the German auto company said on Tuesday.

"Only new cars are subject to the measure," a company spokesman told Agence France Presse adding that customers confronted with the ban are to be offered alternate models.

Physicists said Tuesday that a so-called optical lattice clock, touted by some as the time-measuring device of the future, had passed a key accuracy test.

The performance boosts chances that the world's timekeepers will one day adopt it for defining the second, they said.

The next rover to Mars should hunt for signs of ancient life and gather rocks that a future mission could bring back to Earth for the first time, a team of scientists appointed by the U.S. space agency said Tuesday.

The scientists' new report outlines ambitious goals for a mission to Mars that NASA wants to launch in 2020.

Australia admitted Wednesday conditions at the Great Barrier Reef are "poor" as it battles UNESCO threats to downgrade its heritage status over concerns about pollution and development.

Environment Minister Mark Butler released a report card showing that the reef's health had slumped since 2009 due to cyclones and floods, despite progress on reducing agricultural runoff.

The world typically sees about 90 tropical cyclones a year, but that number could increase dramatically in the next century due to global warming, a U.S. scientist said Monday.

Rising greenhouse gas emissions could lead to a 10 to 40 percent increase in the frequency of tropical cyclones by the year 2100, said prominent climate scientist Kerry Emanuel of the Massachusetts Institute of Technology (MIT).

It took longer than expected, but NASA's Curiosity rover is finally heading toward a Martian mountain.

The nuclear-powered, six-wheel rover drove a total of 190 feet (58 meters) since July Fourth, leaving the spot where it spent the past seven months examining rocks and dirt.

A new study links heavy air pollution from coal burning to shorter lives in northern China. Researchers estimate that the half-billion people alive there in the 1990s will live an average of 5½ years less than their southern counterparts because they breathed dirtier air.

China itself made the comparison possible: for decades, a now-discontinued government policy provided free coal for heating, but only in the colder north. Researchers found significant differences in both particle pollution of the air and life expectancy in the two regions, and said the results could be used to extrapolate the effects of such pollution on lifespans elsewhere in the world.