Asteroid 2014 EC
This afternoon asteroid 2014 DX110 zoomed by the Earth at a distance closer than the moon. NASA said:
As happens about 20 times a year with current detection capabilities, a known asteroid will safely pass Earth Wednesday closer than the distance from Earth to the moon.

This asteroid, 2014 DX110, is estimated to be about 100 feet (30 meters) across. Its closest approach to Earth will be at about 217,000 miles (about 350,000 kilometers) from Earth at about 1 p.m. PST (4 p.m. EST) on March 5. The average distance between Earth and its moon is about 239,000 miles (385,000 kilometers).
We're all more aware of these small yet dangerous asteroids that slide right by the Earth because, one, NASA and others are getting better at discovering them on approach; and, two, there was that surprise meteorite that blew up over Chelyabinsk last year (see gallery below), injuring hundreds and generally freaking people out.

Now, as Slate reports, a smaller one will pass even closer tonight ... and of particular note, it was spotted just yesterday:
An asteroid called 2014 EC that was discovered only last night will pass the Earth just after midnight UTC tonight, sliding past us at a distance of just 56,000 km (35,000 miles) above Earth's surface! This rock is roughly 10 meters across - half the diameter of the Chelyabinsk asteroid. A miss is as good as a mile, as they say, but it shows that there are lots of these things passing us all the time.
As the veil lifts and we humans get better at seeing just how much danger is circling our little blue life raft, scientists and enthusiasts are arguing that we need a plan. In response, the U.N. has established the International Asteroid Warning Network for that purpose.

Asteroid 2014 EC_1
This diagram shows the orbit of asteroid 2014 EC, which passed close to Earth this afternoon. EC's orbit is shown in blue, with the portion of it inside the Earth's orbit in dark blue.
The U.N. plan, which was drawn up and pitched by the Association of Space Explorers, also calls for finding those objects years out that could strike the Earth and sending up rockets to knock them off their course ... thereby crashing into some other civilization in our galaxy.

"The residual impact risk - from asteroids with yet-unknown orbits - is shifting to small-sized objects," Peter Brown, a planetary scientist at the University of Western Ontario, told Nature recently.

The Associated Press added in a story last year about the dangers of these smaller, mostly undetected, near-Earth objects:
Meteors about the size of the one that streaked through the sky at 42,000 mph and burst over Chelyabinsk, Russia, in 2013 - and ones even larger and more dangerous - are probably four, five or even seven times more likely to hit the planet than scientists believed before the fireball, according to three studies published Wednesday in the journals Nature and Science.

That means about 20 million space rocks the size of the Chelyabinsk one may be zipping around the solar system, instead of 3 million, NASA scientist Paul Chodas said at a news conference.
There's nowhere for us to go just yet, so perhaps we should take more seriously the efforts to guard our rock in space.