Supernovae suggest the universe is growing slower than expected

Don't look now, but what you know about the universe's growth might have been turned on its ear. University of Arizona scientists have learned that a certain type of supernova (Ia) isn't the reliable measuring stick for universe expansion that previous data would suggest. By comparing optical and ultraviolet images (such as in the hybrid image you see above), they found that older, farther exploding stars aren't behaving in the same way as newer ones closer to our own star. In other words, the ancient supernovae aren't necessarily as distant as you'd think -- and if they aren't, the universe isn't growing as quickly as textbooks say.

The tricky bit is finding out just how inaccurate our existing model might be. It'll require combing through legions of optical and UV images to get a clearer answer. When that happens, though, researchers will have a better understanding of what's happened since the Big Bang, including the amount of dark energy that exists in the cosmos.

[Image credit: NASA/Swift]