The first of the large asteroids that will breach the Minimum Orbit Intersection Distance (MOID) of 0.05 AU (4.6 million miles) is asteroid 163348, also known as 2002 NN4. At between 820 to 1,870 feet in diameter, it is larger than the Empire State Building and around the length of a large sports stadium.
According to the NEO Close Approach data table, which documents near-Earth objects and the dates they approach our planet, asteroid 2002 NN4 will make its closest approach to Earth on June 6, at 3:20 a.m. UTC, and at its closest will reach a distance of 3.16 million miles to Earth.
Any object larger than 150 meters that passes within 4.6 million miles of Earth is considered potentially hazardous, according to NASA. However, the distance at which asteroid 2002 NN4 is approaching Earth can be regarded as safe.
Another asteroid named 2013 XA22 will breach the MOID on Monday, June 8 at 3:40 p.m. UTC and coming within 1.8 million miles of Earth, will be significantly closer than 2002 NN4. However, it is much smaller in size at 240-525 feet in diameter, and will fly by at relative velocity of 15,000 mph.
Finally, asteroid 441987 (2010 NY65), which was discovered a decade ago, will cross Earth on Wednesday, June 24, at 6:44 a.m. UTC and will breach the MOID at 2.33 million miles from Earth.
The 2010 NY65 asteroid falls between 460 and 1,015 feet in diameter and will have the highest relative velocity among the three large asteroids, at 28,800 mph.
Asteroids, sometimes called minor planets, are rocky, airless remnants left over from the early formation of our solar system about 4.6 billion years ago. There are currently 958,621 known asteroids, according to NASA.
The majority of asteroids can be found orbiting the sun between Mars and Jupiter within the main asteroid belt, and range in size from Vesta—the largest at about 329 miles in diameter—to bodies that are less than 33 feet across. The total mass of all the asteroids combined is less than that of Earth’s moon.
There are three main types of asteroids: the C-type (chondrite) which are most common and most ancient and consist of clay and silicate rocks, and are dark in appearance; the S-types (“stony”) which are made up of silicate materials and nickel-iron; and the M-types, which are metallic (nickel-iron). The composition of M-types are related to how far from the sun they formed, with some experiencing high temperatures after they formed and partly melted, with iron sinking to the center and forcing basaltic (volcanic) lava to the surface.