An asteroid large enough to destroy a city will make a rare pass by Earth this weekend, coming close enough to spot with a telescope, "or perhaps even with some good binoculars," per the New York Times. Thankfully, there's a 0% chance that 2024 MK, discovered less than two weeks ago, will hit Earth. But the space rock, some 400 to 850 feet across, will come within 75% of the distance of the moon at 9:46am ET Saturday. "Passes this close by things this big are rare," planetary astronomer Andrew Rivkin tells the Times, noting this is the third known case of an asteroid squeezing between Earth and the moon this century.
A much larger asteroid, capable of ending civilization, will fly by Earth around 4:14pm ET Thursday but at a much greater distance than 2024 MK. Asteroid 2011 UL21, between 1.1 and 2.4 miles across, will pass by at 17 times the distance between the Earth and moon. The distance of 4.1 million miles is reassuring since 2011 UL21 is larger than 99% of all known near-Earth objects. It's likely one of the 10 biggest asteroids to pass within 4.7 million miles of our planet since 1900, says Gianluca Masi, director of the Virtual Telescope Project, per Live Science. Thursday marks the asteroid's closest approach in at least 110 years.
We'll learn more about both space rocks as radar systems track and measure them. "These measurements will reduce the uncertainties in their motion considerably and enable us to compute their trajectories further into the future," Lance Benner, an asteroid researcher at NASA's Jet Propulsion Laboratory, tells the Times. The approach of 2011 UL21 will only be viewable with a strong telescope. Stargazers in the US, especially in the Southwest, have a better shot of seeing 2024 MK appear as a speck of light as it whizzes by. At this link, you can input your location and viewing time for instructions on where to look in the night sky. (More asteroid stories.)
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