Apophis is a near-Earth asteroid that was discovered on April 19, 2004 by astronomers at the Kitt Peak National Observatory in Arizona. It is classified as a potentially hazardous asteroid (PHA) due to its close approaches to Earth and its relatively large size. Apophis has a diameter of approximately 320 meters (1,050 feet) and a mass of about 27 million metric tons.

On April 13, 2029, Apophis will make a close approach to Earth, passing within only 38,000 kilometers (24,000 miles) of the surface. This close approach will be the closest encounter between a known asteroid and Earth in recorded history. Apophis is predicted to pass so close to Earth's surface that it will be visible to the naked eye from some locations on Earth.

The close approach of Apophis in 2029 will have a significant effect on the asteroid's orbit. The gravitational pull of Earth will alter the asteroid's trajectory, causing it to move closer to the Sun and enter an Earth-crossing orbit. This change in orbit will increase the likelihood of Apophis colliding with Earth in the future.

The probability that Apophis could collide with Earth increases during these periods. The closest approach in 2036 is currently estimated to carry the highest risk of impact, with a probability of 1 in 100,000.

If Apophis were to impact Earth, the consequences could be devastating. The impact of an asteroid the size of Apophis could cause widespread damage and loss of life. The impact would also create a large crater and throw up a huge amount of dust and debris into the atmosphere, which could cause a global climate crisis.

Scientists are currently working on strategies to mitigate the potential threat of Apophis. One possibility is to use a spacecraft to nudge the asteroid off its trajectory and prevent it from colliding with Earth. Another possibility is to use a nuclear weapon to destroy the asteroid before it reaches Earth.

The threat posed by Apophis is a reminder of the importance of monitoring near-Earth asteroids and developing strategies to mitigate the potential risks they pose.