From VOA News
Science & Health
by – Walter Wisniewski
A relatively large asteroid will cross Earth’s orbit around the sun this month. Astrophysicists and astronomers say there is no chance of a collision, but it will be the closest flyby of an asteroid that large for at least another 10 years.
Asteroid 2014 JO25, discovered three years ago, is about 650 meters (2,100 feet) in diameter, 60 times as large as the small asteroid that plunged into our atmosphere as a meteor and exploded over the Russian city of Chelyabinsk in 2013. That blast was felt thousands of kilometers away and caused havoc on the ground, damaging more than 7,000 homes and offices and injuring 1,500 people.
Asteroid 2014 JO25’s pass by Earth on April 19 will be a near miss, cosmically speaking. The U.S. space agency NASA said no one should worry: “There is no possibility for the asteroid to collide with our planet, [but] this will be a very close approach for an asteroid of this size.”
The Minor Planet Center of the International Astronomical Union classifies 2014 JO25 as a “potentially hazardous asteroid.” (Astronomers classify asteroids as “minor planets”; when they pass close to Earth they are termed “near Earth objects.”)
An animation of the intersection of Earth’s orbit and that of 2014 JO25, prepared by the Jet Propulsion Laboratory, a unit of the California Institute of Technology, makes it look like an awfully close call, but the hard facts are more reassuring: At its closest point, the asteroid will be about five times as far from Earth as the moon is, more than 1.75 million kilometers away (1,087,400 miles).
Although the asteroid is expected to be twice as reflective as our moon, it will be difficult to spot in a night sky filled with stars, and certainly not without help. Scientists say the sort of telescope amateur astronomers use should be adequate to pick out the space rock as it whizzes across the sky at 120,000 kilometers per hour (74,500 mph).
EarthSky.org, a website that follows developments in the cosmos and throughout nature in general, has posted an article with detailed information to help sky-watchers find the asteroid on April 19, and for a day or two afterward.
Professional astronomers also will be tracking 2014 JO25 closely. Puerto Rico’s Arecibo Observatory, an extremely powerful radio telescope center, will study the asteroid for five days.
After all, it’s not often that something as big as this comes along, even a couple of million kilometers from home. NASA says 2014 JO25 hasn’t been this close to Earth in the past 400 years, and it will be at least 500 years before it comes back for a repeat close encounter with our planet.
Asteroids actually pass close to Earth fairly often, but it’s their size that matters. Asteroid 2017 GM made one of the closest passes by Earth ever seen — 16,000 kilometers (9,900 miles) above sea level — less than a week ago, on April 4. Little notice was taken, however, because that chunk of space rock was about the size of a small car.