NASA-International Space Station

The most important asteroid in the sky is currently yours for the perusing with binoculars -- and perhaps even the naked eye.

Tonight, Wednesday, Feb. 17, Vesta, the second most massive object in the asteroid belt, reaches what astronomers like to call "opposition." An asteroid (or planet or comet) is said to be "in opposition" when it is conflicting to the sun as seen from Earth. In other words, if you were to stand outside with the sun directly above you at high noon, Vesta would be straight below your feet some 211,980,000 kilometers (131,700,000 miles) away. With Vesta at opposition, the asteroid is at its adjoining point to Earth in its orbit.

Wednesday night, the asteroid is predictable to shine at magnitude 6.1. That brightness should make it visible to concerned parties brandishing telescopes or binoculars, and even those blessed with excellent vision and little or no light pollution or clouds in their vicinity. Vesta will be visible in the eastern sky in the constellation Leo.

What makes this space rock so famous these days? Along with its relative proximity at this point, a full half of the asteroid is being bathed by sunlight when seen from Earth, making it emerge brighter. Another attribute working in the observer's favor is that Vesta has a exclusive surface material that is not as dark as most main belt asteroids - allowing more of the sun's rays to reflect off its surface.

If spotting Vesta in the night sky has whetted your appetite for mega-rocks, all we can say is, stay tuned. NASA's Dawn spacecraft, currently motoring its way through the asteroid belt, will begin its exploration of Vesta in the summer of 2011.

A report released on Friday by the National Academy of Sciences claims almost nothing is being done to discover and destroy smaller objects in space that are perhaps a more likely threat that bigger asteroids and obvious threats.

The National Academies report says it is extremely probable that the next destructive impact will be something less than 50 metres (164 feet) across. This happens about once every 1,000 years. The last one hit over Tunguska, in Siberia, in 1908, destructing forests. If one hit a populated area today, it would cause destruction akin to a severe hurricane or tornado.

The term given to space matter that could potentially intimidate the planet is 'Near-Earth Objects' - asteroids, comets or really big pieces of rock that may wander close to Earth. About 6,200 near-Earth asteroids have been recognized, the largest being 1036 Ganymed, which is 20 miles (32 km) across.

Like the moon and Mars, which are covered in craters, the Earth is also often bombarded. But erosion, the association of continents, the oceans and even forests obscure them over time.

Objects one kilometre (just over half a mile) across hit the Earth about once in a million years. Something this big could harm a large region or cause a vast tsunami if it hit an ocean.

Objects of about 5 km (three miles) or larger could kick up enough dust to cause inclusive damage for years, perhaps decades of cold and dark conditions, and could cause mass extinctions.

"Luckily such events are exceptionally rare, the last known being about 65 million years ago," the report reads.

Your own possibility of dying in a large cosmic impact is 1 in 40,000, not because it is likely but because such an impact would kill so many people that it raises the odds. In contrast, your own risk of dying in a flood is 1 in 30,000, while the risk of death from a motor vehicle accident is 1 in 100.

NASA's Wide-field Infrared Survey Explorer, or WISE, has covered its first never-before-seen near-Earth asteroid, the first of hundreds it is likely to find during its mission to map the whole sky in infrared light.

The near-Earth object, designated 2010 AB78, was revealed by WISE Jan. 12. After the mission's complex software picked out the moving object against a background of stationary stars, researchers followed up and confirmed the discovery with the University of Hawaii's 2.2-meter (88-inch) visible-light telescope near the summit of Mauna Kea

The asteroid is at present about 158 million kilometers (98 million miles) from Earth. It is estimated to be roughly 1 kilometer (0.6 miles) in diameter and circles the sun in an elliptical orbit tilted to the plane of our solar system. The object comes as close to the sun as Earth, but because of its twisted orbit, it is not thought to pass near our planet. This asteroid does not pose any predictable impact threat to Earth, but scientists will continue to monitor it.

WISE, which began its all-sky survey on Jan. 14, is anticipated to find about 100-thousand previously undiscovered asteroids in the Main Belt between Mars and Jupiter, and hundreds of new near-Earth asteroids. It will also spot millions of fresh stars and galaxies.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the WISE for NASA's Science Mission Directorate, Washington. The principal researcher, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA. The ground-based observations are partially supported by the National Science Foundation.

Asteroid 2010 AL30, exposed by the LINEAR survey of MIT's Lincoln Laboratories on Jan. 10, will make a close approach to the Earth's surface to within 76,000 miles on Jan. 13 at 12:46 pm Greenwich time (7:46 am EST, 4:46 am PST). Because it’s orbital period is almost the same to the Earth's one year period, some have suggested it may be a manmade rocket stage in orbit about the sun. However, this object's orbit reaches the orbit of Venus at its neighboring point to the sun and nearly out to the orbit of Mars at its furthest point, crossing the Earth's orbit at a very steep angle. This makes it very doubtful that 2010 AL30 is a rocket stage. Furthermore, trajectory extrapolations show that this object cannot be connected with any new launch and it has not made any close approaches to the Earth since well before the Space Age began.

It seems more likely that this is a near-Earth asteroid about 10-15 meters in size, one of about 2 million such objects in near-Earth space. One would expect a near-Earth asteroid of this size to pass within the moon's distance about once every week on average. The asteroid does not pose a risk, in fact, stony asteroids under 25 meters in diameter would be predictable to burn up in our atmosphere, causing little or no ground damage.