An asteroid the size of a refrigerator was spotted by telescopes in Hawaii on Saturday, just before it collided with Earth's atmosphere and burned as a fireball in the sky due south of Puerto Rico. The harmless space rock, officially named 2019 MO, never had a chance of making it to the ground or doing much damage, as it was only about a tenth the size of the bolide that exploded in the atmosphere over Russia in 2013. What's most interesting about 2019 MO, though, is the fact that it was spotted by telescopes beforehand. That's only happened four times...