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Black Holes And Gravitons

In Gravity by Brian Koberlein6 Comments

During the Archean Eon of planet Earth, when life was figuring out how to harness energy from the Sun, two black holes in a distant galaxy merged with a ripple of gravitational waves. Over the next 2.9 billion years these ripples traversed a vast and empty space, while on Earth a plucky little species of bipeds learned to use lasers and mirrors to measure gravitational vibrations smaller than the nucleus of an atom. When the gravitational ripples reach Earth, they become humanity’s third detection of merging black holes. Read More

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Lunar Reconnaissance Orbiter Hit By Meteoroid

In Meteors by Brian Koberlein3 Comments

Impact strikes are a rare but dangerous threat to spacecraft. The highest threat is for spacecraft in near-Earth orbit, where decades of satellite debris have accumulated. Given the tremendous speeds of orbiting spacecraft, even a fleck of paint can pose a threat. Beyond Earth orbit the threat is less, but it isn’t zero, as demonstrated by a rare impact with the Lunar Reconnaissance Orbiter (LRO) currently orbiting the Moon. Read More

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How To Define Distance In An Expanding Universe

In Cosmology by Brian Koberlein6 Comments

Recently the Sloan Digital Sky Survey (SDSS) has completed the largest map of the universe thus far. The map focuses on the positions of quasars. These objects are powered by supermassive black holes in the centers of galaxies, and are so bright they can be seen from the farthest regions of the cosmos. Most quasars are so far away that we have to redefine what “distance” means. In an expanding universe, distance can be defined in a variety of ways. Read More

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A Young Star System Holds Clues About The History Of Our Own

In Exoplanets by Brian Koberlein2 Comments

Ten light years away there is a star that could tell us about the origins of our solar system. Known as Epsilon Eridani, it is a bit smaller and cooler than our Sun, but similar in composition. It is also only about 500 million years old, giving us a view of what our own solar system may have been like in its youth. New work now finds the system is similar to our own. Read More

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The Dark Web

In Dark Matter by Brian Koberlein0 Comments

Dark matter is difficult to study. Since it doesn’t interact with light, it is basically invisible. But it does have mass, and that means it deflects light ever so slightly, an effect known as weak gravitational lensing. By observing the way light from distant galaxies is distorted, we can map the distribution of mass between us and the galaxies. Comparing this to the visible matter of galaxies allows us to map the presence of dark matter. This technique works well when measuring large regions of dark matter, such as the halos around galaxies, but gravitational lensing is such a weak effect it’s difficult to study the detailed structure of dark matter. That’s unfortunate, because the details are what we need to understand the nature of dark matter. Read More