Bus-sized Asteroid Passes Just 150,000 km From Earth

In the first of two fly-bys this year, asteroid MD 2011 made its closest pass to Earth but fear not, it’s not close enough the present any danger.

Bus-sized asteroid passes just 150,000 km from Earth
A massive asteroid made its closest approach to Earth in February - it was just 15,000,000 km away

An asteroid the size of a bus whizzed past the Earth at a distance of just 15,000,000 km on February 4th and will make a second approach in August this year. It’s one of several asteroids expected to make close fly-bys of Earth in 2024.

Described as a ‘Near Earth Asteroid’ by NASA, MD 2011 orbits the sun every 396 days at 0.00 astronomical units (AUs) from Earth's orbit at its closest point, meaning its orbit is very close to Earth's and much closer than those in the asteroid belt.

Asteroid detection

Astronomers can detect asteroids using optical telescopes which capture the light reflected from the asteroid. MD 2011 was first discovered by a pair of robotic telescopes in New Mexico that scan the skies for near-Earth asteroids.

“As asteroids move against the background of fixed stars, they can be identified by their motion across the sky,” explains Dr Minjae Kim, a Research Fellow in the Department of Physics at University of Warwick. “Some telescopes are designed to detect infrared light, which is heat radiation emitted by asteroids. Infrared telescopes are particularly useful for detecting dark asteroids, which do not reflect much visible light but emit infrared radiation.”

By studying an asteroid's orbit and dimensions using infrared telescopes, and understanding its composition through visible light, scientists can determine the likelihood of an impact and estimate the asteroid's mass, Kim adds. “This evaluation is crucial in assessing potential threats and devising strategies to divert these space rocks from Earth’s path, exemplified by missions like DART.”

Bus-sized asteroid passes just 150,000 km from Earth
Several asteroids are due to fly past the Earth this year. Photo by Justin Wolff on Unsplash.

Kim says that despite “frequent sensationalist media coverage about distant asteroids,” there is often no real danger. “Of course, if a significant asteroid threat were imminent, the public would be well-informed by Planetary Defence at NASA,” Kim says but as yet,“ NASA hasn't issued a warning about a dangerous asteroid impact since most celestial objects of interest pass by safely…While the likelihood of a direct hit on land is reduced due to Earth's vast oceans, the potential impact of an asteroid remains a serious concern.”

NASA will continue to discover and track asteroids, with the aim of surveying all significant Near-Earth objects. Additionally, the Double Asteroid Redirection Test (DART) mission had a critical role in demonstrating that we have the technology and expertise needed to target and alter the orbit of an asteroid during a high-speed encounter. This significantly reduces concerns about potential asteroid threats.