Did 3I/ATLAS Cross 76000 Km in 18 Minutes? - Social Media Stunned at The Comet's Behaviour

3I/Atlas is back in the viral spotlight on social media, with people flabbergasted by its speed. A new post on social media has caused a meltdown among astronomy enthusiasts. This viral post says that 3I/ATLAS was observed streaking across the sky, covering roughly 76,600 kilometres in just 18 minutes, implying an apparent motion of nearly 71 km/s.

But that's not all: the attached photo, reportedly captured on a device called 'Seestar S50,' shows a bright trail against a static background of stars, leading them to proclaim it the 'cleanest sky plane displacement ever recorded.' If true, this could change our view of comets.

What the Viral Tweet Claims About 3I/ATLAS

Now, according to the viral tweet, the long-exposure image taken from Hawai'i on the night in question shows a long, straight streak against a background of motionless stars, and even the details given are exact. The streak is 47 pixels long, and using the Seestar's scale of 4.07 arcseconds per pixel, that converts into an angular drift of 191.29 arcseconds, or about 3.19 arcminutes.

Moreover, with the comet reportedly at a distance of around 1.84 astronomical units from Earth at the time (roughly 275.3 million kilometres),this angular drift is converted into a linear displacement of about 76,590 km over 18 minutes, which gives an apparent sky-plane speed of ~70.8 km/s. Here is the tweet:

Furthermore, the tweet also says that this does not correspond to the comet's actual heliocentric speed as measured by agencies like NASA / JPL, which is around 54 km/s, basically indicating that the 'streak' represents a projection on the sky, exaggerated by geometry and long exposure instead of the comet literally wrecking through space at 70 km/s relative to Earth.

That is not all, as the image also includes a bright coma roughly 87,000 km across and an estimated nucleus size of 1–3 km. The post also frames this as 'interstellar physics in motion' and a scarce chance to visually catch an object from another star system racing through our cosmic neighbourhood.

Read More: 'Spaceship Engine' Found in New Images of 3I/ATLAS? - Here Is the Truth

Read More: WATCH: Did 3I/ATLAS Send A Message To Earth? Viral Video Decoded

What the Facts and Science Actually Indicate

Now, to fact-check these claims, it's essential to understand the study around 3I/Atlas, since its discovery on 1 July 2025 by the ATLAS (Asteroid Terrestrial Impact Last Alert System) survey telescope in Chile, 3I/ATLAS has been heavily studied by astronomers worldwide. It is the third confirmed interstellar object, following 1I/ʻOumuamua and 2I/Borisov. Its hyperbolic trajectory and high velocity relative to the Sun confirm its interstellar origin.

According to NASA data, the nucleus of 3I/ATLAS is between 0.44 km and 5.6 km wide (approximately 440 metres to 5.6 kilometres), based on Hubble Space Telescope observations. Its speed when first detected was about 221,000 km/h (roughly 61 km/s), accelerating to about 246,000 km/h (~68 km/s) near perihelion, which is very in line with the behaviour of a hyperbolic interstellar visitor.

Moreover, in many previous cases, scientists have stressed that the apparent large displacement in images such as the one described in the tweet is primarily due to observational geometry, projection onto the sky plane, and long-exposure photography, not a literal measurement of instantaneous velocity relative to Earth.

The comet's hyperbolic trajectory means it glides through our Solar System at high speed. Still, the 76,600 km in 18 minutes refers only to the projected path on the sky, not its actual spatial displacement relative to Earth.

Furthermore, recent peer-reviewed observations of 3I/ATLAS reinforce that its characteristics remain consistent with those of natural interstellar comets. Studies of its coma, dust tail, and chemical composition show typical cometary activity, such as outgassing driven by ices sublimation, dust and gas release, and evolution of coma brightness and colour as it moves through the solar radiation.

Finally, all mission-level data from NASA and the European Space Agency (ESA) confirm that 3I/ATLAS poses no hazard to Earth. Its closest approach will still leave it well beyond Earth's orbit, at about 1.8 astronomical units (approximately 270 million km).

So, the measurement from the viral post refers to a projection onto the sky plane, derived from a long-exposure image that captured the motion of 3I/ATLAS relative to the background stars. Translating the streak length into physical distance depends on angular displacement and the comet's approximate distance from Earth at the time.

Under those assumptions, that amounts to roughly 76,600 km in 18 minutes, which is equivalent to about 71 km/s. However, that does not imply the comet suddenly accelerated or zoomed past like a rocket through space.