On April 19th a considerable sized asteroid will pass about 4.6 lunar distances (1.8 million km) from Earth.  While there is no chance of it impacting our planet, this 650m asteroid was only discovered three years ago, and it will be the closest encounter of a large asteroid since asteroid Toutatis in September 2004. The next predicted fly-by of a large asteroid is 2027 with 800m wide 1990 AN10.

The expected magnitude could reach up to 11 during the close approach, hence a decent sized scope will be required, and due to the rapid movement may be hard to locate and track.

Sky chart for asteroid 2014 JO25 covering April 18th to 20th 2017

And as a bonus, comet PanSTARRS (C/2015 ER61) will also make its closest approach to Earth on the 19th, but 10 times farther away as the asteroid.  I should be visible with small telescopes or binoculars in the constellation Aquarius in the dawn sky.

Source: NASA/JPL