Another asteroid will buzz the earth today -- the second such flyby in 48 hours.

The asteroid 2014 EC, which was discovered March 5 by the Catalina Sky Survey near Tucson, Ariz., is approximated at about 25 feet across and expected to will safely pass the earth this afternoon, at about 1:21 p.m. Pacific Standard Time, or 4:21 p.m. EST.

Passing six times closer than the moon, the asteroid at its closest will be an estimated distance of 38,300 miles, or, 61,600 kilometers, for the blue planet. That equals about four or five Earth-diameters away, not be visible to the naked eye.

"This is not an unusual event," Paul Chodas, a senior scientist in the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory, Pasadena, Calif., said in a news release. "Objects of this size pass this close to the Earth several times every year."

A Wednesday flyby of the larger 2014 DX110 asteroid, estimated at about 100 feet across, came within about nine-tenths the distance to the moon.

A third asteroid, 2014 EF, which is closer in size to today's 2014 EC, passed Earth at about 7 p.m. PST (10 p.m. EST) Wednesday, with its estimated distance about twice as far from our planet as 2014 EC's closest approach will be.

Through the Near-Earth Object Observations Program, commonly referred to as "Spaceguard," the National Aeronautics and Space Administration identifies and tracks asteroids and comets using both telescopes on the ground and positioned in space.

The program also records the specifics of each approach by specific objects and from that determines if any could be potentially hazardous to the earth.

According to NASA, there are millions of asteroids orbiting our sun, many thought to be the shattered remnants of space materials that were never able to coalesce into actual planets.

Scientists say of known asteroids are found in the asteroid belt between the orbits of Mars and Jupiter, although some look more to be in co-orbit with Jupiter.

Near-Earth asteroids, however, represent a different group altogether.

More information about asteroids and near-Earth objects is at: https://www.jpl.nasa.gov/asteroidwatch.