The Andromeda and Milky Way galaxies, with their 1.2 trillion stars, are on course to collide at 1 million miles an hour.

While humanity eventually might need sunglasses and seat belts for the rocky cosmic ride, there's no immediate need for panic. The smashup won't even begin to occur for another 2 billion years.

But James Lombardi Jr., an associate professor of physics at Allegheny College in Meadville, Crawford County, has worked for years to develop a computer model to explain stellar collisions. That knowledge also has provided him insight into the dynamics of intergalactic collisions.

He and two of his students have used his model to simulate stellar collisions that could occur when the Milky Way and Andromeda sideswipe each other and eventually coalesce into a giant egg-shaped galaxy.

"It's known that galaxies will collide, but the details of what will happen may not be entirely known," Dr. Lombardi said. "But we understand the physics enough to make statistical predictions."

The Discovery Channel interviewed Dr. Lombardi for its recent documentary, "Cosmic Collisions: Galaxies," which described what the future holds when Andromeda, now 2.4 million light-years from Earth, collides with our Milky Way.

Jethro Nededog, a writer and producer with Workaholic Productions, the Los Angeles company that produced the show, said he contacted Dr. Lombardi to discuss stellar collisions, but discovered him to be a gold mine of information. That explains why he's included in four of the show's six segments.

"He has the ability, in my opinion, of someone with a high level of knowledge who can explain things in laymen's terms," Mr. Nededog said, noting that Dr. Lombardi offered "some of the most poignant" information in the documentary. "When you find a person with the ability to discuss topics in a way that the average person can understand, you want to go back to them time and time again."

Chances are negligible, Dr. Lombardi said, that existing stars will collide when the two galaxies merge, because of the enormous distances between stars. But collision of gas clouds in each galaxy could trigger formation of billions of new stars, whose close proximity to one another could produce stellar collisions.

Stars, like the sun, are gases in plasma form. Dr. Lombardi used such information in his computer code to gauge what happens when stars collide. "Once you model the gravitational and pressure forces, you know how to move around the gases of the stars," he said.

During formation of a blue straggler, for example, heat from the collision makes gases glow many times brighter than the two original stars. "We were one of the first groups that worked on this," he said. "It's the kind of thing you can work on for years to refine the physics."

Two of Dr. Lombardi's students, seniors Alexander Brown of Bethel Park and Kyle Gearty of Fairview, Butler County, also have used his model to simulate how star collisions could produce such exotic objects as binary neutron stars and possibly intermediate mass black holes.

The team's research has been featured on the History Channel series, "The Universe," with their animations used in the planetarium show "Cosmic Collisions" at the American Museum of Natural History, the National Air and Space Museum, the Museum of Nature and Science, and the Shanghai Science and Technology Museum.

The sun is but one of the Milky Way's 200 billion stars, Dr. Lombardi said, noting its locale two-thirds of the way along one of the spiral arms making up the Milky Way, which is one of 100 billion galaxies in the universe.

There are as many stars in the universe as dry grains of sand on all of Earth's beaches, he said. For mathematicians, that equates to 1 followed by 22 zeroes. Each galaxy is believed to have a black hole at its center.

Dr. Lombardi knows one thing about our astronomical future: "Andromeda and the Milky Way will collide," he said. People already have begun naming the new galaxy. The show used the name "Milkomeda."

Despite the neglible chance that stellar collisions will rearrange our solar system, the Earth's future could be threatened by a gamma-ray burst if one occurs within a few thousand light-years of our planet. Such bursts are thought to occur when binary stars merge.

And Earth will not remain intact once the sun exhausts its core hydrogen fuel supply in a few billion years. When that occurs, the sun's outer layers will expand to reach Earth's orbit and reduce the planet to an ember.

Talk about global warming.

"If people, as a species, are able to survive several billion years into the future, we'll have to colonize another planet in a nearby star system or build an artificial planet at a safer distance from the sun," Dr. Lombardi said.

But in billions of years, traveling to other planets and solar systems might be a routine venture. So, at least for now, it's premature to book that spaceship reservation.