Two surprisingly large Near-Earth Asteroids have been discovered in just the last week or so, as well as a third moderately large asteroid which surprisingly has also gone undetected until now, even though it can pass close enough to the Earth to be classified as "potentially hazardous".
Not since 1983 has any near-Earth asteroid been found as large as the approximately 20-kilometer (12-mile) size of the two new large ones. In fact, there are only three other known near-Earth asteroids that are of comparable size or larger than the two new large ones.

© NASA/JPL-CaltechThe orbits of 2013 UQ4, 2013 US10 and 2013 UP8 are shown in a view looking down on the plane of the solar system. While 2013 US10 and 2013 UP8 orbit the sun in a counter clockwise direction (so called "direct" orbits like all the planets and most asteroids), 2013 UQ4 orbits in a clockwise (retrograde) direction.
It is important to note that none of these three new large near-Earth asteroids can come close enough to the Earth to represent a near-term threat to our planet.
The first of the new large near-Earth asteroid discoveries is named 2013 UQ4, and it is perhaps the most unusual. This approximately 19-kilometer (12-mile) wide object was spotted by the Catalina Sky Survey on Oct. 23 when the asteroid was 435 million kilometers (270 million miles) away from Earth. Not only is this object unusually large, it follows a very unusual highly inclined, retrograde orbit about the Sun, which means it travels around the Sun in the opposite direction of all the planets and the vast majority of asteroids.