Tampa, Fla. -- Did you know that just a few days ago we avoided what could've been a major disaster? A massive asteroid just barely missed Earth.

Scientists say that huge rock, bigger than a house, came closer to us than the moon. And, you should know, before you go breathing a sigh relief that another one is scheduled to do the same thing and just about six days.

So, why are scientists having such trouble seeing these things coming?

10News WTSP took its doomsday dilemma to Antonio Paris, astronomy guru at the Museum of Science and Industry, or MOSI, in Tampa.

For all of our satellite and telescopes, he was asked why we are still so bad and spotting objects so big.

“You're correct," said Paris, "There could be one headed this way and it could be a last-minute thing before we actually see it's going to hit us. The larger these things are, the easier they are to spot it's the little ones that we tend to not really find. And when we do, it's a little too late."

The word “little," is relative. Rocks the size of a bus, even a building may go unseen.

Paris showed a meteorite at MOSI -- a 350-pound 4 1/2 billion-year-old space rock made mostly of iron and nickel.

It's similar in size to another mystery meteorite that lit up Russia’s skies a little over three years ago. The shockwave from that one, as it exploded in the upper atmosphere, blew out windows and damaged buildings.

These recent, undetected asteroids could've been as bad. Maybe worse, he said.

"It also depends on where it hits," said Paris, "is it going to hit the side of a mountain? In the desert? In the ocean? All of these things play a factor."

And what if it hits a city?

"It'll be a bad day," said Paris.

So, what might help?

Scientist have developed a space telescope to track near-Earth objects. It's called a NEO-cam.

It could help spot up to 10 times as many asteroids, but last week for the second time, NASA chose not to fully fund the NEO-cam project.

Another problem is that even if an asteroid big enough to cause a catastrophe was coming from the direction of the sun it could be too small, in comparison, for us to spot it. Blinded by our nearest star.

"Something major, even catastrophic, we still probably would not be able to see it if the sun was blocking it," said Paris.

Paris says those catastrophic impacts happen like clockwork just about every 75 million years.

The last one wiped out the dinosaurs 66 million years ago.

That's enough time, perhaps, for us humans to improve our rock-spotting skills.

But stopping a collision once we see a major asteroid heading in our direction could be an even bigger problem.