A massive “planet-killer” asteroid will come very close to Earth today (June 27), safely zipping past our planet at about 58,000 miles per hour (93,000 km/h). The ‘potentially dangerous’ mountain-sized object is one of the largest space rocks to pass close to Earth in more than a century – and you can watch the close encounter live.
The asteroid, 2011 UL21, is a near-Earth asteroid, meaning its orbit sometimes puts it within 1.3 astronomical units (AU) of the sun — or roughly 1.3 times the average distance between Earth and the sun.
It orbits our home star once every three years. Based on past observations, the space rock is somewhere between 1.1 and 2.4 miles (1.7 to 3.9 kilometers) wide, according to SpaceReference.orgmeaning it is larger than 99% of known near-Earth asteroids, according to European Space Agency (ESA).
2011 UL21 is probably at least 10 times smaller than the largest space rock ever to hit Earththe asteroid Vredefort and about five times smaller than the rock that destroy the dinosaurs about 66 million years ago.
However, while any potential impact from 2011 UL21 would be less extreme than these historic impacts, the asteroid still has the potential to cause continental-scale damage and eject enough debris into the atmosphere to cause significant climate change, which is why considered a “planet killer”.
Asteroid 2011 UL21 will come within about 4.1 million miles (6.6 million kilometers) of Earth, closer than it has been to our planet in at least 110 years, according to simulations by NASA’s Jet Propulsion Laboratory (JPL). At this distance it is considered that a potentially dangerous object by NASA. However, this is still about 17 times farther from our planet than The moon.
Although the space rock poses no threat to Earth – not now or in the future – it is interesting because it is likely one of the 10 largest asteroids to pass within 4.7 million miles (7.5 million km ) of our planet since 1900. Gianluca Massiastrophysicist and director of the Virtual Telescope Project (VTP), writes in a recent statement.
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You can watch the closest approach of 2011 UL21 thanks to a free live stream from VTP, who will share the view of the asteroid from the Bellatrix Astronomical Observatory in Ceccano, Italy. The stream begins at 4:00 PM ET on June 27, with close approach expected to occur 15 minutes later.
You may also be able to spot the asteroid in the night sky with a decent telescope. It will be brightest on June 28 and June 29 and should be visible from the northern hemisphere if you know where to look. At its brightest, it will have a brightness similar to Proxima Centauri, the closest known star to the sun, according to VTP.
2011 UL21 won’t approach Earth again until 2089, when the space rock will come within 1.7 million miles (2.7 million kilometers) of our planet — more than two and a half times closer to us than it is now its approach, according to JPL simulations.
There is zero chance of any known planet-killing asteroid hitting Earth at least for the next 1000 years. However, there will be some close calls with smaller asteroids in the next few years. For example, the asteroid Apophis, which is large enough to destroy an entire city, will do so pass Earth closer than some satellites in 2029.
