The asteroid will pass closest to Earth on March 5. Will it pass millions of miles away, or as closely as 11,000 miles (17,000 km)?

Asteroid 2013 TX68 is a small asteroid with an uncertain trajectory that will pass close to Earth on March 5, 2016. Although the distance of its pass is not precisely known at this time, scientists say it will be a safe pass and that they will soon precisely define its orbit. It could fly past Earth as far away as 9 million miles (14 million km) or as close as 11,000 miles (17,000 km). For comparison, the moon’s distance is about a quarter-million miles. Astronomers at NASA’s Jet Propulsion Laboratory say the variation in possible nearest distances for this asteroid is due to the wide range of possible trajectories for this object, which was tracked for only a short time after its discovery in 2013.

Some estimates indicate the space rock may pass at 311,000 miles (500,505 km), which is about 1.3 Earth-moon distances.

However, if the asteroid passes at its closest possible distance of just 11,000 miles (17,000 km), the flyby will be an exceedingly close one, less than 2 times Earth’s own diameter. If that were the case, the asteroid would come even closer than orbiting communications satellites.

There is no scenario being considered at this time for an impact, and there is no danger, scientists say.

Why is there uncertainty in the trajectory?

The asteroid was discovered by the Catalina Sky Survey on October 6, 2013, as it approached Earth on the nighttime side of our planet. After three days of observations and tracking, the space rock passed into Earth’s daytime sky and could no longer be observed.

Although scientists do know that asteroid 2013 TX68 will not impact our planet during the upcoming flyby, the lack of observations in 2013 means they cannot now precisely predict its orbit.

Preliminary estimates of the size of asteroid 2013 TX68 suggest the space rock has a diameter of 38 meters (125 ft), which is more than twice the size of the Chelyabinsk meteor that entered over Russian skies in February, 2013.

If a space rock of this size were to enter our atmosphere, it would produce a shock wave at least twice as intense as that of the Chelyabinsk meteor, which broke windows in six Russian cities – caused more than 1,500 people to seek medical care, mostly due to cuts from flying glass – and did other damage to thousands of buildings.

Asteroid 2013 TX68 is travelling at a speed of 32,212 miles per hour (51,840 km/h).

It may come even closer on September 28, 2017, but then the chance of impact is no more than 1 in 250 million, according to NASA.

How close will asteroid 2013 TX68 pass in early March?

We will find out very soon, but scientists are not concerned. Paul Chodas, manager of NASA’s Center for Near Earth Object Studies, said:

The possibilities of collision on any of the three future flybys are far too small to be of any real concern.

I fully expect any future observations to reduce the probability even more.

Read more about asteroid 2013 TX68 at JPL’s site

Bottom line: Astronomers know that asteroid 2013 TX68 will pass closest to Earth on March 5, 2016, but they do not know at this time if its closest approach will be millions of miles away or as close as 11,000 miles (17,000 km).