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13 April 2029: A 41-Million-Ton City-Killer Threading the Needle at 19,656 Miles (31,634 km)

Primary-source guide to the Friday, 13 April 2029 (21:46 UTC) perigee of asteroid 99942 Apophis—skimming just 19,656 miles (31,634 km) above the Atlantic Ocean (2,580 miles inside the geostationary satellite ring and under one-tenth the distance to the Moon), 750–1,200 megaton regional-devastation physics, 100-year hazardous/ELE close-pass comparison table, and unaided-eye viewing.

Key Orbital and Physical Parameters of the 13 April 2029 Perigee (21:46 UTC)

A 1,115-foot asteroid skimming underneath our TV satellites. At 5:46 p.m. EDT (21:46 UTC) on Friday, April 13, 2029, the 1,115-foot (340-meter) stony-iron asteroid (99942) Apophis will pass just 19,656 miles (31,634 km) above the Atlantic Ocean. That is less than one-tenth the distance to the Moon and 2,580 miles (4,152 km) closer to Earth than our ring of geostationary weather and TV satellites (22,236 miles up). Radar proves Apophis will miss us safely, but a 41-million-ton rock that size carries 750 to 1,200 megatons of energy, a reminder of why planetary defense matters. [1] [2]

1. Distance above the ground (19,656 miles / 31,634 km). At closest approach, Apophis passes 23,620 miles (38,012 km) from Earth's center, which is 19,656 miles above the mid-Atlantic Ocean (29.4°N, 42.6°W). Because the Moon sits 252,506 miles away that night, Apophis comes more than 10 times closer than the Moon. [1] [2] [3]

2. Flying 2,580 miles inside the geostationary satellite belt. Our main weather and communications satellites (like NOAA's GOES-19) orbit 22,236 miles (35,786 km) above the equator. Apophis dips 2,580 miles inside that satellite ring, but because its path is tilted 40° to the equator, it passes well clear of active satellites. [1] [2]

3. Weight (~41 million tons) & naked-eye visibility. Radar images from Goldstone and Arecibo show a peanut-shaped stony-iron rock about 1,115 to 1,230 feet (340–375 m) across, weighing roughly 41 million metric tons. On the night of April 13, 2029, under a dark New Moon (0.2% lit), Apophis will shine as brightly as the stars of the Little Dipper (magnitude +3.1), letting millions of people across Europe, Africa, and western Asia watch it glide across the sky with the naked eye. [3] [4] [5]

How Close Is 19,656 Miles—and What Would Happen If It Hit?

How close is 19,656 miles? In space terms, 19,656 miles (31,634 km) is a hair's breadth—less than the distance around Earth's equator (24,901 miles), or about seven round-trip flights between New York and Los Angeles. At Apophis's approach speed, arriving at Earth's orbit just 50 minutes earlier would have turned a safe pass into a direct hit. [1] [6]

What if a 1,115-foot asteroid actually hit Earth? While global dinosaur-ending asteroids are 1 to 6 miles wide, a 1,115-foot (340 m) rock is what planetary-defense agencies call a regional or state-killer:

• 750 to 1,200 megatons of impact energy. Hitting the atmosphere at 28,200 mph (12.6 km/s), an Apophis-sized rock releases 15 to 24 times the energy of the 50-megaton Tsar Bomba (the largest nuclear test in history) and 75 times the 1908 Tunguska airburst in Siberia. [4] [14]

• A 3-mile crater and state-wide blast wave on land. Standard impact physics (Collins, Melosh & Marcus 2005) shows a land strike would blast a crater 3 miles (5 km) wide and 1,500 feet deep, trigger a magnitude 7.0 earthquake, and flatten buildings across a 60-to-90-mile radius, devastating an entire US state or European country. [14]

• Ocean impact tsunami. If a rock that size struck the mid-Atlantic Ocean, it would launch deep-water tsunami waves that would pile up into 30-to-100-foot (10-to-30-meter) waves along the US East Coast, the Caribbean, Europe, and West Africa within hours. [14]

Closest Large Hazardous & Regional/Global-Scale Asteroid Passes in the Last 100 Years (1926–2029)

The closest large asteroid pass in over 100 years. Checking NASA/JPL's database from 1926 through 2029 shows that Apophis's 2029 flyby at 0.10 Lunar Distances (19,656 miles up) is the closest known pass of a large hazardous asteroid in a century (1 Lunar Distance = 238,855 miles / 384,400 km): [1] [15]

A sobering lesson from the table below. Three of the closest passes of the last 100 years—in 1933, 1957, and 2001—were only discovered 16 to 62 years after those asteroids had already flown past Earth unseen. [15]

2029 Flyby Geometry & Orbital Altitude Scale (Miles & Kilometers)

How Apophis compares to satellites and the Moon. The table below compares Apophis's April 13, 2029 altitude against the Space Station, GPS satellites, geostationary TV satellites, and the Moon: [1] [2] [3]

From Torino Scale 4 (2004) to Zero Impact Risk (March 2021 Goldstone Radar)

Why astronomers worried in December 2004. Apophis was discovered in June 2004 at Kitt Peak in Arizona and re-spotted in December 2004. Early orbit estimates over Christmas week 2004 briefly showed a 2.7% chance (1 in 37) that it would hit Earth on April 13, 2029, reaching Level 4 on the Torino hazard scale. Days later, older March 2004 photos ruled out a 2029 hit, but left open a tiny chance that sunlight heating the rock (the Yarkovsky effect) could steer it through a narrow 'keyhole' in 2029 to hit Earth in 2036 or 2068. [1] [6] [7]

How March 2021 radar proved Earth is safe for 100+ years. In March 2021, NASA's 230-foot Goldstone radar dish in California and the 330-foot Green Bank Telescope in West Virginia bounced precision radar beams off Apophis from 10.4 million miles away. That measurement pinned down its 2029 distance to within ±2.5 miles (±4 km), ruled out the 2036 and 2068 keyholes, and proved on March 26, 2021 that Apophis has zero chance of hitting Earth for at least the next 100 years. [1] [2]

Earth's Tidal Torque, Asteroid Quakes, and the Jump from Aten to Apollo Orbit

Earth's gravity bends its orbit and shakes its surface. Flying just 19,656 miles above Earth bends Apophis's path by 28.3 degrees and stretches its year around the Sun from 324 days to 423 days (moving it from an 'Aten' orbit inside Earth's path to a wider 'Apollo' orbit). [1] [6]

Asteroid quakes and spin changes. Radar shows Apophis is a peanut-shaped two-lobed rock that tumbles slowly every 30.6 hours. During the 2029 pass, Earth's gravity will tug harder on the near end than the far end, changing its spin speed by several hours and likely triggering tiny dust slides that expose fresh unweathered rock on its surface. [4] [8] [9] [10] [11]

The Spacecraft Armada at Apophis: NASA OSIRIS-APEX & ESA RAMSES

Two spacecraft will watch the flyby up close. Because an asteroid this large passes this close only once every ~7,500 years, space agencies are sending two missions to fly alongside it:

• NASA's OSIRIS-APEX mission. After dropping off samples from asteroid Bennu in 2023, NASA's OSIRIS-REx spacecraft was renamed OSIRIS-APEX and steered toward Apophis. It will arrive in April 2029, map the asteroid's surface and spin changes for 18 months, and fire its thrusters near the surface to stir up and study the rock layer. [12]

• Europe's RAMSES mission. Approved by the European Space Agency, RAMSES is set to launch in April 2028 and arrive in February 2029—two months before closest approach—so it can watch Earth's gravity stretch and twist the asteroid in real time. [13]

• Related update: ESA's Hera sees two asteroids (Mainstream — Measured). Hera is a different ESA planetary-defense mission. In mid-October 2026, its camera showed the asteroid Didymos and its small moon Dimorphos as two separate objects for the first time, from 1,280 km away. Dimorphos is 151 m across, which ESA says is about the size of the Great Pyramid of Giza. Didymos is 780 m wide, and the pair orbit about 1.15 km apart. [16]

• What Hera will check. In 2022, NASA's DART spacecraft hit Dimorphos at 6.1 km/s and changed its orbit by about 33 minutes. Hera will study the crash site up close. ESA plans to share the first detailed images of Dimorphos on November 25. [16]

• Open question: why was the push so big? ESA says the deflection was much greater than impact simulations predicted. Hera's measurements of Dimorphos's mass, makeup and structure should help explain why. [16]

How, Where and When to Watch Apophis with the Naked Eye on 13–14 April 2029

Where and when to look on Friday, April 13, 2029. On the evening of April 13, 2029, Apophis rises over the Southern Hemisphere and races northwest across the night sky over Europe, Africa, the Canary Islands, and the Middle East. [1] [2]

A dark New Moon makes naked-eye viewing easy. April 13, 2029 falls on a dark New Moon (only 0.2% lit). From Europe, North and West Africa, and the Canary Islands, you will be able to spot Apophis with your naked eyes as a steady magnitude +3.1 star gliding visibly past background stars, moving more than the width of the full Moon every minute through binoculars. [1] [3]

Frequently asked questions

Sources were checked on 2026-10-29. Text on this page is original. Quoted figures are attributed and linked to the source. General education only, not for safety or operational decisions. Disclaimer.