There is no reason to panic when Asteroid 2005 YU55, passes by the Earth on Tuesday.

NASA scientist said the space rock poses no threat to Earth even as it will be at range of about 201,700 miles or 324,600 kilometers on Tuesday at 6:28 p.m. ET at its closes, which is closer that the moon which is about 238,854 miles (384,399 kilometers) away.

"This is particularly exciting, since it is the first time since 1976 that an object of this size has passed this closely to the Earth," Scott Fisher, a program director of the National Science Foundation's Division of Astronomical Sciences said.

In fact, astronomers are ready for this rare cosmic event, including setting up telescopes like the giant Arecibo radio telescope in Puerto Rico and several NASA Deep Space Network instruments.

Observatories in Hawaii will also attempt to take spectroscopic measurements of the asteroid to analyze its composition, researchers said.

But what is there about asteroids that the science world is all agog with rare cosmic event?

Space.com provided five reasons why we should care about asteroid.

• Asteroids may explain why planets are diverse. The materials in asteroids represent the building blocks of the planets. Because of the position of the asteroid belt that lies between the rocky inner planets and the gas giants of the outer solar system, the materials found there may hold clues as to why the planets are so diverse today.

• Asteroids may explain how life started on Earth. Scientists do not fully understand how the first life forms arose on Earth from non-living organic matter, and asteroids may help us learn about how life arose on our own planet.

• Asteroids could be sources of valuable metals. But to be able to investigate the feasibility of such operations, it is important to know more about asteroid composition and the technical aspects of traveling to them.

• Asteroids complement other planetary studies. Besides the opportunity for mining, these asteroids are also interesting from a scientific perspective, because studying them complements our studies of the major planets.

• Asteroids are may help scientists prepare for future flybys or even possible collisions. In April 2010, President Barack Obama reportedly announced the next goal for Americans in space: visiting an asteroid by 2025 because according to astrophysicist John Grunsfeld - a former NASA astronaut who flew on five shuttle missions - sending humans to purposely move an asteroid, to nudge the space rock to change its trajectory could show that humanity could deflect a space rock if one threatened to crash into the planet.

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Asteroid 2005 YU55 to Pass by Earth Next Week: But What If It Hit?