Image copyright NASA/JPL-Caltech/GSSR Image caption This composite of 30 images of asteroid 2014 JO25 was generated using Nasa's Goldstone Solar System Radar in California's Mojave Desert

A large asteroid the size of the Rock of Gibraltar has passed safely by Earth.

The object, measured to be almost a kilometre wide, came within five times the distance between the Earth and the Moon.

Known as 2014 JO25, the asteroid is the biggest such space rock to skim our world since 2004.

Astronomers say the best opportunity to view the rock will come in the dark hours of Wednesday night.

Radar imagery using Nasa's 70m (230 ft) antenna at the Goldstone Deep Space Communications Complex in California reveal a peanut-shaped asteroid that rotates about once every five hours.

The asteroid passed Earth at a distance of 1.8 million km (1.1 million miles) at 13:24 BST on Wednesday, 19 April.

The next known encounter of an asteroid of about this size will occur in 2027 when the 800m-wide (half-mile-wide) asteroid 1999 AN10 will fly by at one lunar distance, about 380,000 km (236,000 miles).