The term "comet" comes from the Greek "kometes" meaning long hair, referring to the tail.

The flyby spacecraft is about the size of a Volkswagen Bug.

The impactor is about 3 X 3 feet, about the size of a desk and weighs 370 kg (820 lbs).

The entire combined spacecraft weighs about 1 ton.

The impact did not knock the comet out of its orbit because the force of the collision between the impactor and the comet was like a moving truck hitting a pebble. It did not affect the speed or direction of the comet to any noticeable degree.

The closing speed of the comet to the impactor is 10 times faster than a speeding bullet.

The crater is expected to be up to the length of a football stadium and several stories deep.

The ejecta curtain coming out of the crater might look like what you get when you throw a rock into a can of paint (funnel shaped spray).

If you view the impact of Comet Tempel 1 from Earth with a large telescope it might look like a bright flash followed by a glowing stream. It would take a couple of minutes after the flash for the "stream" to separate from the center of the comet.

It takes 7 1/2 minutes for the flyby spacecraft signal to reach Earth. Once the mission is within its last hour, there is no time for the team on Earth to communicate effectively with the twin spacecraft. That is the reason auto navigation systems are being built into the flight plan.

The communication time between the flyby spacecraft and the impactor takes less than one second.

Prior to impact, the flyby spacecraft moves away from the comet to a safe location for observation of the event.