Historical Record

Notable asteroid
close approaches

Some asteroid passes have set proximity records. Others reached the atmosphere and made themselves known without warning. This page covers both - the closest confirmed flybys and the atmospheric events that shaped how planetary defence is funded and prioritised.

Apophis - the 2029 flyby →

Closest confirmed flybys

Non-impacting passes sorted by miss distance from Earth's surface. Distances from Earth's centre are roughly 6,371 km greater.

Date	Object	Size	Miss (surface)	Note
13 Nov 2020	2020 VT4	~5 m	~370 km	Passed below ISS orbital altitude. Discovered after the flyby.
26 Jan 2023	2023 BU	4–8 m	~3,600 km	Closest confirmed pre-detected pass. Discovered five days before flyby.
28 Jun 2011	2011 MD	5–20 m	~12,000 km	Passed through the geostationary belt. Small enough to pose no surface threat.
18 Mar 2004	2004 FH	~30 m	~43,000 km	First asteroid tracked passing inside geostationary orbit altitude.
13 Apr 2029	Apophis 2029	~370 m	~31,000 km	Closest known pass by a large asteroid. Naked-eye visible. Multiple spacecraft planned.

The Apophis 2029 encounter

On 13 April 2029, Apophis - a 370-metre asteroid - will pass roughly 31,000 km above Earth's surface. That places it below the ring of geostationary communication satellites at 35,786 km. No known asteroid of similar size has passed this close in the era of systematic tracking.

The flyby carries no impact risk. What makes it significant is what it enables: the closest ever observation of a large near-Earth asteroid from Earth, combined with planned spacecraft visits from multiple agencies. The encounter will also test orbital prediction models at very short range, where gravitational effects are most pronounced.

When asteroids reached the atmosphere

Not all notable events were safe flybys. These objects entered the atmosphere - some never reaching the ground intact, one predicted to the minute before arrival.

Date	Event	Size	Energy	Note
15 Feb 2013	Chelyabinsk object	~20 m	~500 kt	~1,500 people hospitalised with glass injuries. Arrived undetected from Sun direction.
2 Oct 2008	2008 TC3	~4 m	~1–2 kt	First asteroid predicted to hit Earth before impact. Meteorites recovered.
30 Jun 1908	Tunguska object	50–80 m	10–15 Mt	Largest confirmed impact in modern history. Flattened ~2,000 km² of Siberian forest.

Why the proximity record keeps improving

The confirmed close-approach record has been broken multiple times in the past decade. That is not because asteroids are getting closer - it is because survey telescopes are getting better. ATLAS, Pan-STARRS, and Catalina Sky Survey now detect objects a fraction of the size that earlier systems could see.

Small asteroids are common and many pass at short range. Most go undetected because they are too faint until they are very close. Post-flyby detections - where an object is found in archival imagery after its closest pass - are likely to continue adding entries to the record table.

The Chelyabinsk event in 2013 was a reminder that the most dangerous sub-threshold objects arrive without warning. That event directly accelerated investment in short-warning survey infrastructure, particularly ATLAS, which is specifically designed for rapid detection of objects in the final hours or days before a potential encounter.

Apophis asteroid

Full details on the 370-metre asteroid and its 2029 flyby.

Asteroid miss distance record

The full table of closest confirmed passes.

Will an asteroid hit Earth?

Current risk assessment and what history tells us.

Planetary defence

How NASA would respond to a confirmed impact threat.

Common questions

What is the closest confirmed asteroid flyby on record?

Asteroid 2020 VT4 passed approximately 370 km above Earth's surface on 13 November 2020 - closer than the International Space Station's orbital altitude. The object was roughly 5 metres across and was discovered only after the flyby. Asteroid 2023 BU holds the record for the closest pass detected before it happened, at around 3,600 km above the surface on 26 January 2023.

How close will Apophis come to Earth in 2029?

On 13 April 2029, asteroid 99942 Apophis will pass approximately 31,000 km above Earth's surface - closer than the ring of geostationary satellites at 35,786 km altitude. Apophis is roughly 370 metres across, making it the largest asteroid to pass this close to Earth in recorded history. It will be visible to the naked eye over Europe, Africa, and Asia during the flyby.

What happened at Chelyabinsk in 2013?

On 15 February 2013, an asteroid roughly 20 metres across entered the atmosphere over Chelyabinsk, Russia at around 67,000 km/h. It exploded at approximately 30 km altitude in an airburst releasing energy estimated at 500 kilotons of TNT. The shockwave broke windows across a wide area and sent roughly 1,500 people to hospital with cuts from flying glass. The object was not detected beforehand - it arrived from the direction of the Sun.

What was the Tunguska event?

On 30 June 1908, a rocky object estimated at 50-80 metres across entered the atmosphere over the Podkamennaya Tunguska River in Siberia. It exploded at around 8-10 km altitude, releasing energy estimated at 10-15 megatons of TNT and flattening approximately 2,000 km² of forest. The object disintegrated before reaching the ground, so no crater formed. Due to the remote location, no human deaths were confirmed from the impact itself.

Why are some very close asteroid passes discovered only after the flyby?

Small asteroids - under about 10 metres - reflect little light and are difficult to detect with current survey telescopes until they are very close. Some pass quickly enough that even a few days of lead time is not available. Objects arriving from the direction of the Sun are especially hard to spot, as ground-based telescopes cannot point toward the Sun. Short-warning survey networks like ATLAS are designed specifically to catch these late detections.