3I/ATLAS is racing through space at well over 130,000 miles per hour, with its top speed near the Sun reaching around 153,000 miles per hour (about 246,000 km/h).

What 3I/ATLAS Is

3I/ATLAS is an interstellar comet, meaning it came from outside our solar system rather than from the usual comet reservoirs like the Kuiper Belt or Oort Cloud.

Its path is so energetic and hyperbolic that it is not gravitationally bound to the Sun and will leave the solar system after a single fly-through.

How Fast Is It Traveling?

Speeds depend on where it is along its trajectory:

  • At discovery: about 137,000 mph (221,000 km/h, roughly 61 km/s).
  • Hyperbolic excess speed (its “cruising” speed through the solar system): about 58–61 km/s relative to the Sun.
  • Near closest approach to the Sun (perihelion, October 2025): about 68 km/s, roughly 153,000 mph (246,000 km/h).

Some outreach descriptions and videos round this to 130,000–150,000 mph and call it the fastest comet ever recorded.

Why It Can Go So Fast

3I/ATLAS moves so fast because:

  • It was likely ejected from a distant planetary system long ago, picking up a large “departure speed” relative to our Sun.
  • As it falls toward the Sun, gravity accelerates it further, boosting its speed near perihelion before it slingshots back out.

Its hyperbolic speed (tens of km/s) is much higher than that of typical long- period comets and even significantly faster than earlier interstellar visitors like 1I/ʻOumuamua and 2I/Borisov.

Is It Dangerous?

Despite the dramatic numbers, there is no known impact risk:

  • It does not come closer than about 170 million miles (270 million km) from Earth.
  • Current trajectories show a one-time passage through the inner solar system before it escapes into interstellar space again.

TL;DR:
If you’re asking “how fast is 3I/ATLAS traveling” in simple terms: it’s moving at roughly 130,000–150,000 mph through the inner solar system, peaking near 153,000 mph when it swung closest to the Sun.