Feb. 19, 2007  -- Circle your calendar. April 13th, 2036 could be a really, really bad day on planet Earth.

A group of astronauts and engineers warns that an asteroid may pass uncomfortably close to Earth that day. The chances it will actually hit are just one in 45,000, but even at those odds, the scientists warn, the United Nations should consider a response.

Potential Threat

The scientists met this past weekend in San Francisco to discuss the potential threats asteroids pose to the Earth and what can be done to prevent a possible collision.

Most feared is Apophis, a large asteroid that will pass within 10,000 miles of Earth around 2029 and even closer in 2036.

Dr. Dan Barry, a retired astronaut, told ABC News, "Even if the probability is low of an asteroid hitting Earth, if it has the potential to have a significant impact, then it has to be looked at. It is the absolutely responsible thing to do. In fact, it would be irresponsible not to do so."

Barry said more research is needed so that when a potentially dangerous asteroid is found, there is a plan in place. He said it is therefore important to start the search for asteroids now, to allow enough time to effectively deal with them.

Scientists believe that if advance warnings of dangerous asteroids like Apophis can be made decades in advance, there will be enough time to try and knock them off course.

Suddenly, Bruce Willis on a mission to stop a devastating asteroid from destroying Earth, as he did in the movie "Armageddon," does not seem as far-fetched.

What Are The Solutions?

Nobody knows for sure what it would take to push a massive asteroid off its course, but the theoretical possibilities include detonating weapons on an asteroid's surface or using gravitational pull to alter a possible collision course.

But it could also break an asteroid into many pieces, all still headed toward Earth.

Some scientists say a better option could be to launch a large satellite to rendezvous with an asteroid. The mass of the satellite alone could produce enough gravitational pull to change the asteroid's course.

Another suggestion is to crash a spacecraft into an asteroid in the hopes of changing its direction.

"Done far enough away, only a small deflection would be needed and it is kept in one piece," said Barry.

In 1996, NEAR became the first spacecraft launched by NASA to orbit and land on an asteroid. The purpose of the mission was to determine the asteroid's mass, structure, gravity and magnetic field. Scientists hoped this important information would help them understand asteroids.

So, while astronauts blowing up an asteroid may be movie fiction for now, scientists are already thinking about how to save Earth from a massive asteroid possibly on its way.