Tonight may be the closest we come in a generation to staring down a bullet the size of a skyscraper.

A battleship-size asteroid will miss hitting Earth today by about 334,000 miles, scientists say. It is about 95,000 miles farther out than the moon. The NASA-sponsored Catalina Sky Survey discovered the asteroid TU24 on Oct. 11, 2007. It has been estimated to be 500 to 2,000 feet in size and originated from an area of the solar system between Mars and Jupiter. This is the closest an asteroid of this size has ever come to Earth, NASA officials said. Another asteroid of this size is not expected to come near Earth again until 2027, scientists say.

“The fact that asteroids like TU24 pass so close to the Earth is something that we need to be aware of,” said Dr. Andy Rivkin of the Johns Hopkins Applied Physics Laboratory in Laurel.

While NASA is sure an impact with the Earth is not possible, that doesn’t stop astronomers from contemplating the worst possible scenarios.

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If an asteroid of this size hit Washington, the damage would be tremendous, Rivkin said. The crater would likely consume most of the capital and throw debris as far as Pennsylvania.

Each year, 40 tons of space rock hit Earth, and it is estimated that more than 2,000 Earth-crossing asteroids exist in space greater than 1 kilometer across, according to the book “Impact Earth,” by British astronomer Austen Atkinson.

A meteor crater in Arizona is just more than half a mile in diameter, Rivkin said. It was created by a projectile much smaller in size than asteroid TU24.

“They are important not only because of the potential hazard they pose to civilization, but they also give us an opportunity to learn about the solar system and in coming decades and centuries will probably be a source of resources for astronauts,” Rivkin said.

The physics laboratory did not do any imaging of the asteroid, because most telescopes must be programmed a month in advance. It decided to rely on the efforts of local stargazers.

TU24 will be closest to Earth at about 3:33 a.m. Eastern Standard Time, NASA officials said. The asteroid will still be within viewing range tonight, but not without a telescope. This is because the asteroid will be 50 times fainter than something visible to the naked eye.

The asteroid can be viewed by using a modest amateur’s telescope equipped with a least a 3-inch aperture. A dark, clear sky far away from the city lights is preferable. The asteroid will be near the constellation Ursa Major tonight, NASA officials said.

mcedrone@baltimoreexaminer.com