Earth is welcoming a rather hefty visitor to the neighborhood Wednesday — an asteroid that hasn't swung by these parts in roughly 400 years. About as big as the Rock of Gibraltar, asteroid 2014 JO25 ...

Diagram showing the orbit of 2014 KH39. Yellow shows the portion of its orbit above the plane of Earth's orbit (grey disk); blue is below the plane. When farthest, the asteroid travels beyond Mars ...