5 days to impact

Deep Impact is on target to impact comet Tempel 1 on the 4th of July.

For the last five billion years of our planet's violent history, Earth has been walloped by comets. These small bodies and their asteroid cousins whacked Earth often in its early years, knocking the stuffing out of our young world. As the solar system matured, impacts happened less often—but they have never ceased. Earth bears its scars in the form of weathered craters and extinct species.

This 4th of July is payback time. For the first time in history, Earth gets to strike back.

According to the article, results from this impact could one day be used to save us from a comet bound for Earth - which reminds me of a section from A Short History of Nearly Everything (see yesterdays post). Bill points out that nuking an incoming comet, while currently totally impractical for a bunch of reasons, is probably not wise. One of the upsides (!) of a major comet strike on the surface is no radiation - if we nuke a comet, we not only break it up into chunks (each of which would still hit us), but we make those chunks radioactive. Joy.