Asteroid 2015 TB145 recognized Oct 10.
October 21, 2015
Asteroid 2015 TB145 will be the biggest known object to pass so close to the Earth until 2027.
Of course, the key phrase there is “known object.” Until October 10, the space agency didn’t know about 2015 TB145; more attention was on asteroid 2009 FD, which will pass within about 4 million miles of Earth on October 29.
Passing by Oct 30-31th : far beyond the moon quite quickly: 34 869 m/s.
Diameter about 600 meter. Coming from Orion