The mountain-sized ‘planet killer’ asteroid will make a close approach to Earth today – and you can watch it live

Planet-Killing Asteroid Makes Close Approach to EarthPlanet-Killing Asteroid Makes Close Approach to Earth A massive “planet killer” asteroid named 2011 UL21 made a close approach to Earth on June 27th, safely careening past our planet at a staggering speed of 93,000 km/h. This “potentially hazardous” object, estimated to be between 1.7 and 3.9 kilometers wide, is one of the largest space rocks to pass near Earth in over a century. 2011 UL21 is considered a “planet killer” due to its potential to cause continental-scale damage and disrupt the Earth’s climate. It is classified as a “near-Earth asteroid” with an orbit that periodically brings it within 1.3 astronomical units of the Sun. Despite its ominous nickname, 2011 UL21 posed no immediate threat to Earth during its recent passage. It passed by at a distance of approximately 4.1 million miles (6.6 million km), which is closer than the Moon’s orbit but still a safe distance. The asteroid’s trajectory was closely monitored by NASA’s Jet Propulsion Laboratory, which determined that there was zero risk of impact with Earth. However, the close approach provided an opportunity for scientists to study the object and gain valuable insights into the potential hazards posed by near-Earth asteroids. Members of the Virtual Telescope Project (VTP) set up a live stream to capture images of 2011 UL21 as it approached Earth. This stream gave viewers a glimpse of the asteroid as it hurtled through space. While 2011 UL21 will not return to such a close proximity to Earth until 2089, scientists continue to track and monitor near-Earth asteroids to assess their potential impact hazards.

A huge ‘planet killer’ asteroid will make a very close approach to Earth today (June 27), careening safely past our planet at a speed of around 93,000 km/h. The ‘potentially hazardous’ 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 encounter live.

The asteroid, 2011 UL21, is a near-Earth asteroid, meaning its orbit occasionally puts it within 1.3 astronomical units (AU) of Earth. the sun – or about 1.3 times the average distance between the Earth and the Sun.

It orbits our home star once every three years. Based on previous observations, the space rock is somewhere between 1.7 and 3.9 kilometers wide. SpaceReference.orgmeaning it is larger than 99% of known asteroids close to Earth, according to the European Space Agency (ESA).

2011 UL21 is probably at least 10 times smaller than the largest space rock to ever hit Earththe Vredefort asteroid, and about five times smaller than the rock that the dinosaurs exterminated about 66 million years ago.

While any potential impact from 2011 UL21 would be less extreme than these historic collisions, the asteroid still has the potential to cause continental-scale damage and eject enough debris into the atmosphere to cause significant climate change, and is therefore considered a “planet killer.”

Asteroid 2011 UL21 will zoom by about 4.1 million miles (6.6 million km) from Earth, which is closer than our planet has been in at least 110 years, according to simulations by NASA’s Jet Propulsion Laboratory (JPL). At this distance it is considered a potentially dangerous object by NASA. However, this is still about 17 times further away from our planet than the moon.

The predicted trajectory of potentially hazardous asteroid 2011 UL21. (Image credit: Gianluca Masi, Virtual Telescope Project)

Although the space rock poses no threat to Earth – either now or in the future – it is interesting because it is probably one of the ten largest asteroids to pass within 7.5 million kilometers of our planet since 1900. Gianluca Masian astrophysicist and director of the Virtual Telescope Project (VTP), wrote in a recent statement.

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Related: ‘Planet killer’ asteroids hide in the sun’s glare. Can we stop them in time?

Unistellar eQuinox 2

(Image credit: Jason Parnell-Brookes)

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The closest you can get to the 2011 UL21 is thanks to a free live stream from the VTP, which will share views of the asteroid from the Bellatrix Astronomical Observatory in Ceccano, Italy. The stream will begin on June 27 at 4:00 PM ET, with the approach expected to take place 15 minutes later.

You may also be able to see the asteroid in the night sky with a decent telescope. It will be at its brightest on June 28 and 29 and should be visible from the Northern Hemisphere when you know where should you look. At its brightest, it will have a similar brightness to Proxima Centauri – the closest known star to the Sun, according to VTP.

2011 UL21 won’t come this close to Earth again until 2089, when the space rock will come within 1.7 million miles of our planet – more than two and a half times closer to us than the current approach, according to JPL simulations .

There is zero chance that a known planet-killing asteroid will collide with Earth for at least the next 1000 years. However, there will be some close calls with smaller asteroids in the coming years. For example, the asteroid Apophis, which is big enough to wipe out an entire city, will do that zoom past Earth closer than some satellites in 2029.