[2] While reviewing pictures of the planet Jupiter, astronomer Jennifer Dreiser (Joanna Miles) discovers a new comet streaking through space.

Astronomer Jason Voight (Richard Crenna), a specialist in near-Earth objects, shocks the group by telling them that the comet will hit within 50 miles of Phoenix.

The President does order the nuclear warheads of a Minuteman ICBM to be launched into space aboard a Titan-Centaur rocket, so that an attempt can be made at destroying the comet.

After talking with the President, Governor Ritchie meets with a number of key people, including his chief of staff Elliott Kirkwood (Kip Niven), insurance executive Paul Gilliam (Lloyd Bochner), newspaper owner David Allan (David Dukes), and emergency management officer Wayne Lustus (William Bogert).

Once it has been confirmed that the comet is still on course to hit the Earth, the network broadcast is interrupted with instructions from Civil Defense urging citizens of Phoenix to begin leaving the area immediately.

Governor Ritchie, now understanding the real danger posed by the comet, resolves to withdraw the FCC protest against Sharon's station, and he takes to the TV to urge people to evacuate the city.

This gives Paula the opportunity to get back to her boyfriend, Tom Reardon (Michael Biehn), a rough-and-tumble college student with whom she has a romantic relationship and of whom her father disapproves.

In the hours before impact, Stan Webster (Merlin Olsen), who is leading a group of young boys including his nine-year-old son, Danny (Dino Bachelor) on a survival hike, finds out about the comet over the radio.

With no shelter immediately available, Webster and the boys dig themselves into the desert floor and cover themselves with sleeping bags in a desperate attempt to survive the impact.

Meanwhile, Ann Webster (Jenny O'Hara), who has been in the family station wagon looking for her husband and son, has broken down in the desert and takes cover in a drainage ditch.

David Allan, who had been drafted to help evacuate patients from a local hospital, takes refuge with them in the basement of a bank building downtown.