He covered a few things about the instruments. It's about the size of a bus with the main mirror being 7.5 feet in diameter. It's in a low Earth orbit so that the space shuttle can service it. It's 353 miles up, orbits the Earth in 97 minutes and travels at 19,500 miles per hour.
He researches galaxies and talked a bit about how scientists measure astronomical distances. I'll do that in another post.
He spent some time on the Hubble Ultra Deep Field image.
It's the deepest picture of the universe ever taken in visible light. They pointed the Hubble at the same patch of sky over 800 times over 4 months for a total exposure of 11.3 days. Most everything in it is a galaxy. The faint red ones are 13 billion light years away, which means we're seeing back in time 13 billion years. The universe is 13.7 billion years old, so we're looking at things in the very young universe. There are 10,000 galaxies in the image, each with 2 billion stars!
The part that made this amazing was this. Take a (US) quarter, hold it at arms length, edge-on. You want to see the edge of the coin not the face. They told us that's the area of sky covered by this image, the width of the quarter's edge, square. The wikipedia page actually says the area covered by it "is smaller than a grain of sand held at arm's length". 10,000 galaxies in a swatch of sky the size of a grain of sand; the universe is big.
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