Do organics fall from space onto planets? In 2007, astronomers discovered what they claim is the largest negatively charged molecule yet found in space.

Jupiter, Saturn, Uranus and Neptune - the giant outer worlds in our sun's family - all have many moons. Since the late 1990s, astronomers have found that most moons of these outer planets are 'irregular moons,' probably captured from heliocentric orbits. In many cases, the moons orbits are so tilted that they go around their planets backwards.

In 2007, when astronomers measured the mass of the dwarf planet Eris, they found that it's 27% more massive than Pluto. Astronomer Mike Brown, who discovered Eris, said, "We got lucky in that Eris has a moon going around it. And by tracking the orbit of the moon around the dwarf planet, you actually get to weigh how much the dwarf planet weighs."

They call it 'Einstein's dream come true.' In 2004, astronomers reported the discovery of the first known double pulsar system. Both pulsars have masses greater than that of our sun, but are only 20 kilometers across. Their orbital separation is less than the sun's diameter, and they orbit each other in only 2.4 days. This pulsar pair provides confirmation for Einstein's theory of gravity.

Did Earthly life originate on Mars? Robert Hazen, a scientist at the Carnegie Institution, talked to Earth & Sky about where signs of life off Earth are most likely to be found.

Some astronomers believe that the first signs of life on alien worlds might come from the gentle breathing out of plants. Read more about alien plants here.

Scientists want to know if habitable planets are common. And if they are, how close are some to us? Learn about Gliese 581, one of the 100 closest stars to us.

The largest spiral galaxy known to astronomers is Malin 1. Its disk of stars measures 650,000 light-years across, several times the diameter of the disk of our Milky Way galaxy. In 2007, a newly found image from the Hubble Space Telescope revealed that the central part of Malin 1 looks like an ordinary barred spiral galaxy, somewhat like our Milky Way.

On Oct. 11, 2006, astronomers witnessed a stellar outburst. It was labeled Supernova (SN) 2006jc. This same star had undergone a mysterious outburst two years earlier.

Early stargazers named Neptune for the god of the sea. Now the possibility exists for Neptune to have an ocean of its own ... someday. Astronomers say our sun will become a faint white dwarf star some 8 billion years from now. Then Neptune will cool, possibly causing rain to fall from Neptune's clouds - which might create a water layer, or ocean, up in Neptune's thick atmosphere.