When we talk about what Chandra observes, we're usually discussing things like black holes or galaxies or stars. But Chandra is a pretty amazing telescope and it can study many things in the Universe – including the Earth.

Here's a piece of high-energy astrophysics trivia (you never know when you might need to know these things). Where does the "X" in "X-ray" come from?

Speaking in broad generalities, there are two main classes of physicist: those who generate new hypotheses and those who generate new data. The former are called "theorists" and the latter, in most of physics, are called "experimentalists." In astrophysics, we're called "observers" because we can't do experiments in the traditional sense. We have no knobs to turn, no switches to flip; we can't turn the dial to a maximally spinning black hole just to see what happens (oh, what fun that would be!). Instead, we look at what's already there and try to figure out what it is we're looking at.

This week, the High Energy Astrophysics Division (HEAD) meeting is taking place at the Omni Hotel in downtown Los Angeles, California. What exactly is HEAD?

Dr. Carles Badenes is a Chandra postdoctoral fellow at Princeton, having spent the previous few years at Rutgers University. His main research focus is on supernova explosions and supernova remnants, particularly the class known as Type Ia.

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The Chandra X-ray Observatory is now in its ninth year in orbit around the Earth, and things are sometimes lonely out there. So we've been helping Chandra to use the web to reach out to others who like to network online. Here are a few ways to get in touch with Chandra.

Just as astronomers were getting used to the idea of not knowing what dark matter is, they got a completely different surprise at the end of the 20th century. Instead of slowing down after the Big Bang, the expansion of the Universe was found to be accelerating. Astronomers quickly did what they always do when they come up with something mysterious: they gave it a name. Now, we call whatever it is pushing the Universe apart "dark energy", but the truth is no one knows what it is.

When you look up at the night sky, you see a lot of things glowing like stars, planets, and galaxies. So it might sound strange to hear that most of the Universe is actually dark. The truth is the protons, neutrons and electrons that make up everything we can see - and that means with every telescopes we've got -- accounts for only about 4% of the mass and energy of the Universe. The rest is dark and mysterious. More specifically, about 70% of the Universe is what is known as dark energy; about 26% is so-called dark matter.

Hello! Hopefully by now you'll have read a little about 3C 321, aka the "Death Star Galaxy" from last week's blog entry, which was a transcribed from a presentation I gave a few months ago. I wanted to take this opportunity to give you the insider's view on how we came to discover this amazing system, the point when we knew we had a pretty major result on our hands, and the media frenzy that ensued.

Dr. Dan Evans from the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA, shares some information on 3c321, as of December 2007 now known as the Death Star Galaxy. Dan Evans has never seen Star Wars, so who came up with the nickname? Read on.

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NASA's Chandra X-ray Observatory has opened up a new era of performing x-ray astronomy and x-ray astrophysics.