The "faint sun paradox" has to do with the relationship between the sun's size and Earth's climate.

Is our universe shaped like a sphere, a saddle, or flat? It depends on how you look at it. That will tell us if the universe is open or closed. Read more here.

A recent study suggests that, by the 2080s, extreme summer warming in cities such as Chicago and Atlanta could hover above 100 degrees Fahrenheit. Read more.

He has created a device that could help doctors identify what are called "oncoproteins." This research might eventually enable doctors to better diagnose and treat early-stage cancer.

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.

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.

Here's news about the most famous stellar nursery of all, the Orion Nebula. Previously, the distance to the Orion Nebula was estimated at about 1,500 or 1,600 light-years. But the Orion Nebula is actually closer than that by about 200 light-years, according to Rob Jeffries at Keele University in England.

... but that liquid isn't water. The lakes can't hold water because Titan is so far from the sun that any water on its surface would be solid ice. Instead of having liquid water, Titan's lakes are thought to be filled with methane in a liquid form.

Wolf 359 is one of the closest stars to Earth at only 7.8 light-years away. It is a red dwarf star, known to be a single star. Former studies of bright, easy-to-see stars indicated that most of them lie in multiple systems of two or three stars. But those earlier studies neglected small, faint stars like Wolf 359.