Astronomers have spotted three near-Earth asteroids that were lurking undetected within the glare of the sun. One of the asteroids is the largest potentially hazardous object posing a risk to Earth to be discovered in the last eight years.

The asteroids belong to a group found within the orbits of Earth and Venus, but they’re incredibly difficult to observe because the brightness of the sun shields them from telescope observations.

To avoid the sun’s glare, astronomers leaped at the chance to conduct their observations during the brief window of twilight. An international team spied the space rocks while using the Dark Energy Camera located on the Víctor M. Blanco 4-meter Telescope located at the Cerro Tololo Inter-American Observatory in Chile.

A newly discovered, “potentially hazardous” asteroid almost the size of the world’s tallest skyscraper is set to tumble past Earth just in time for Halloween, according to NASA.

The asteroid, called 2022 RM4, has an estimated diameter of between 1,083 and 2,428 feet (330 and 740 meters) — just under the height of Dubai’s 2,716-foot-tall (828 m) Burj Khalifa, the tallest building in the world. It will zoom past our planet at around 52,500 mph (84,500 km/h), or roughly 68 times the speed of sound, according to NASA (opens in new tab).

The bad news is NASA estimates that it tracks only about 40 percent of the asteroids large enough that they could cause calamity if they were to hit Earth. To save us, the space agency needs fair warning — years, not months or weeks — to muster the defenses in space needed to safeguard the planet.

“As we say, we can’t do anything about them unless we know about them, and when they might be a concern for us,” Lindley Johnson, NASA’s Planetary Defense Officer, said in an interview.