Asteroid 2013 RZ53 passed the Earth at a distance of 243 000 km (60% of the distance to the Moon) on Wednesday 18 September 2013. The asteroid is thought to have an orbit almost identical to that of the Earth, with the effect that it passes us at almost the same time of year for several years as its orbit becomes synchronized with ours, then moves away completely for several decades as it either trails behind or precedes us around the Sun. It is thought that it has passed us in September each year since 2008, and that it will continue to pass us yearly till 2017 (though this passage will drift later into the year), but that prior to 2008 it had not passed close to us since 1959, and that after 2017 it will not approach us again until 2054. This orbit means that it is highly likely that 2013 RZ53 will eventually impact on either the Earth or the Moon, however it does not present any risk to us, since it is at most 3 m across, and would be expected to burn up in the atmosphere above 40 km from the ground. Objects of this size are thought to impact our atmosphere several times a decade.
Asteroid 2013 RZ53 was discovered on Friday 13 September 2013 by the Mount Lemmon Survey at the University of Arizona. The name 2013 RZ53 implies the 1350th object discovered in the first half of September 2013 (period 2013 R).
See also Asteroid 2013 RF74 passes the Earth, Asteroid 2013 RM73 passes the Earth, Asteroid 2013 RT73 flies past the Earth, Asteroid 2013 RS43 misses the Earth and The dust tail of 3200 Phaethon.
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