Asteroid Apophis: Earth's 2029 Visitor

NASA is currently tracking a monstrous space rock named Apophis. This giant is roughly 1,115 feet wide, making it taller than many city skyscrapers. On April 13, 2029, it will glide so close to our home that it will pass beneath the ring of our own weather satellites. Such a close visit from an object this large happens only once every few thousand years, providing a unique opportunity for the global scientific community.

At the Goldstone Deep Space Communications Complex in California, scientists are preparing their giant radio dishes to bounce signals off the surface of the rock. They want to see every crack and bump on its face. Because the asteroid comes so close, the gravity of Earth will actually stretch and squeeze it. This tug-of-war might cause small "asteroid-quakes" that shift the dust on its surface.

The spacecraft OSIRIS-APEX is already on a path to meet this visitor. This ship previously visited another asteroid named Bennu and dropped off a package of space dirt in the desert. Now, led by Daniella DellaGiustina at the University of Arizona, the craft will dive toward Apophis right after it passes Earth. It will use its thrusters to stir up the rocks on the surface to show us what lies beneath. We are basically poking a sleeping giant to see what it is made of.

If you live in Europe or Africa on that Friday night in 2029, you can see it with your own eyes. No telescope is needed to spot this fast-moving light as it zips across the stars. It will look like a bright dot, moving at thousands of miles per hour. While the public watches from the ground, researchers will be looking back at the decades of data that led to this moment.

The Secret History of the Keyhole Argument

For a long time, the scientific community focused on a concern known as a "keyhole." In 2004, Roy Tucker and his colleagues discovered the rock and realized it might hit Earth in 2029. Later calculations showed it would miss in 2029, but suggested it might slide through a tiny 600-meter wide patch of space. If it hit that "keyhole," Earth's gravity would have altered its trajectory to cause an impact exactly seven years later.

Experts debated this possibility for years until Dave Tholen used the Subaru Telescope in Hawaii to prove the path was safe.

Paper trail

This resolution was the result of a rigorous paper trail established since the rock's discovery. The first records come from the Kitt Peak National Observatory in June 2004. Since then, NASA’s Jet Propulsion Laboratory has kept a constant log of its movement in the Sentry Risk Table, while the European Space Agency uses its Neodys system to verify the trajectory.

Every time a new telescope takes a picture, the data regarding its orbit becomes more precise.

However, knowing its path is only one part of the puzzle; understanding its physical nature remains a challenge.

Blind spot

Our biggest blind spot is that we do not know if Apophis is one solid piece or just a pile of rubble. If it is a loose pile of gravel held together by gravity, the Earth's pull might tear it apart during the flyby. Furthermore, small rocks hitting Apophis could nudge it in ways we cannot predict yet. We can see the big rock, but we cannot see the tiny pebbles that might be bumping into it right now. These uncertainties highlight several fascinating characteristics of the asteroid that often go unnoticed.

I bet you never realized

• The Earth's gravity will likely change the way Apophis spins for the next several decades.
• This rock is named after an Egyptian demon of chaos, a reflection of the initial impact concerns.
• If the asteroid were made of solid metal, it would weigh as much as hundreds of aircraft carriers.
• The flyby will be so close that the asteroid might actually move some of our own space junk out of its way.
• Tidal forces from Earth could cause the asteroid to lose its outer layer of dust, making it look refreshed and "younger."

Fresh Discoveries Regarding the Great Space Tug of War

The physical properties of the rock, such as its surface dust and composition, directly influence its movement through the Yarkovsky effect. As the asteroid spins, it soaks up sunlight and radiates it back out as heat, acting like a tiny engine. This thermal push was the main reason scientists could not rule out a 2068 impact risk for many years.

Recently, radar data from the Arecibo Observatory and the Green Bank Telescope analyzed these thermal forces and finally put those fears to rest. Researchers now confirm that for at least the next hundred years, the Earth is safe from a direct hit.