A "potentially hazardous asteroid," named 2011 UL21, recently made its closest approach to Earth, providing a unique viewing opportunity for astronomers and space enthusiasts. With a diameter of 2.3 kilometers, roughly equivalent to 25 football fields, the asteroid is one of the largest near-Earth asteroids to be observed this year, according to NASA.

On June 27, 2011 UL21 passed closest to our planet, and it is predicted to appear at its brightest on June 28 as it moves away from Earth. It is recommended to use small telescopes for an "easily observable" experience. The ideal location for observation is near the constellation Virgo, adjacent to the bright star Spica. Smartphone apps can help enthusiasts pinpoint this position accurately.

Despite some media referring to 2011 UL21 as a "planet killer" capable of causing cataclysmic damage, there is no risk to our planet during this pass. As EarthSky clarifies, the asteroid's closest distance during this approach was already 4,122,350 miles, about 17 times farther than the moon.

While Coloradans will have the opportunity to witness this astronomical event, there is another smaller asteroid to look out for. Newly discovered, the asteroid named 2024 MK measures approximately 400 to 850 feet long and will be passing closer to Earth on June 29. However, it is primarily visible in the southern hemisphere, with a chance of being seen in parts of the southern United States.

For those equipped with telescopes, tonight presents a prime time to observe the closest encounter with 2011 UL21 in the next 65 years. It serves as a reminder of the vast celestial wonders surrounding our planet.